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55V High Efficiency Buck-Boost Power Manager and Multi-Chemistry Battery ChargerDesign Note 531
Charlie Zhao
10/14/531
Figure 1. 15V to 55V Input, 25.2V/6.3A Buck-Boost Battery Charger
IntroductionToday, battery chargers are expected to easily support a variety of battery chemistries and accept a range of voltage inputs, including wide-ranging solar panels. It is increasingly common for input voltage ranges to span above and below the output battery voltage, requiring both step-down and step-up capability (buck-boost to-pology). The LTC4020 buck-boost power manager and multi-chemistry battery-charging controller can take wide-ranging 4.5V to 55V inputs and produce output voltages up to 55V. Its buck-boost DC/DC controller supports battery and system voltages above, below, or equal to the input voltage.
The charger is easily optimized for a variety of battery chemistries. For instance, it can follow a constant-current/constant-voltage (CC/CV) charge algorithm, with either C/10 or timed termination for lithium-based battery systems, a constant-current (CC) characteristic with timed termination, or an optimized 4-step, 3-stage lead-acid charge profile.
6.3A Charger for 25.2V Battery Float VoltageFigure 1 shows a 15V to 55V input, 25.2V/6.3A buck-boost battery charger, featuring a high efficiency 4-switch (M2–M5) synchronous buck-boost DC/DC L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and PowerPath is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners.
dn531 F01
STAT2STAT1BST1BST2
SENSVINSENSTOP
INTVCC
SHDNVIN_REG
RNG/SSILIMIT
VFBMINVFBMAXVFB
FBG
NTCCSOUTMODE
R13100k
C50.22µF0603
SW1SW2
TG1
BG1
SENSBOT
SENSGND
BG2TG2CSP
CSN
BGATE
VBATVC
ITHTIMERRT
LTC4020
PVIN
SGND SGND PGND
R1536k0603
R1647k0603
M1Si7145DP
R18100Ω
R20100Ω
R263k
R273k
R1410k
C400.22µF
0603
C390.22µF
0603
C66.8nF0603
C547pF0603
C4100pF0603
C1, 0.1µF100V, 0603
GNDMODE
BAT25.2V FLOAT6.3A MAX
GND
VOUT21V TO 28V8A MAX
VOUTVBAT
R1920Ω
RCBAT10.008Ω
1W2512
C114.7µF6.3V0603
R1124.9k1%
R1024.9k0.1%
R9226k06031%
R8226k06030.1%
C120.033µF
RCBRB10.002 Ω1W2512
RCBRT10.002Ω1W2512
M4SiR664DP
M2SiR664DP
L15.6µH
WÜRTH 7443556560M3SiR422DP
M5SiR422DP
D6B360A
C190.22µF25V0603
C200.22µF25V0603
C2110µF6.3V0805
D1SBR0560S1
D2SBR0560S1 D4
GRN
D3RED
C1410µF35V1210
C1810µF35V
1210
C2710µF35V1210
C2810µF35V
1210
C15220µF35V35HVH220M
C17220µF
35V35HVH220M
+
+
R5OPT
R2510k
R1100k
R451k
R385.1Ω0805
C256µF63V
63HVH56M
C356µF63V63HVH56M
+
+
GND
VIN15V TO 55V
C23C164.7µF100V1210
10/17/567
EinführungSynchrone Abwärts-/Aufwärtsregler sind vielseitig und hocheffizient. Sie können als Aufwärts- und Abwärtsregler hohe Leistungen abgeben und kommen mit einer einzigen Induktivität aus, was das Design einfach macht. In der Regel werden Abwärts-/Aufwärtsregler in Anwendungen mit hoher Leistung mit normaler oder eher geringer Schaltfrequenz betrieben, was den Wirkungsgrad maximiert und Komplikationen im Zusammenhang mit Querströmen und der Austastzeit der Schalter, zu denen es bei der Synchrongleichrichtung bei hohen Frequenzen kom-men kann, vermeidet. Andererseits lässt sich mit einem Abwärts-/Auf-wärtsregler, der mit einer hohen Frequenz von 2 MHz betrieben wird und deshalb mit einer kleineren Induktivität auskommt, gewährleisten, dass die elektromagnetischen Störaussendungen (EMI) oberhalb des AM-Fre-quenzbandes liegen. Die Besonderheit der Abwärts-/Aufwärtsregler LT8390A und LT8391A liegt darin, dass sie mit 2 MHz arbeiten. Diese hohe Schaltfrequenz er-laubt die Verwendung einer platzsparenden Induktivität, was auch in An-wendungen mit hoher Leistung für kleine Lösungsabmessungen sorgt. Im Unterschied zu monolithischen Wandlern, bei denen die Integrati-on der Leistungsschalter in das IC-Gehäuse für weniger Platz aufwand sorgt, können reine Regler externe Leistungsschalter mit deutlich höhe-ren Spitzenströmen von beispielsweise 10 A ansteuern. Während derart hohe Spitzenströme die kleinen IC-Gehäuse typischer integrierter Wand-
ler thermisch überfordern würden, werden externe, 3 mm × 3 mm große Synchron-MOSFETs ohne weiteres mit dieser Leistung fertig. Da diese MOSFETs zudem dicht gepackt mit den Kondensatoren der entschei-denden Schleife angeordnet werden können, ergeben sich sehr geringe EMI-Effekte. Für weniger elektromagnetische Störaussendungen sorgt außerdem die Tatsache, dass die spezielle Verstärkerarchitektur, die den Scheitelwert des Schalterstroms erfasst, den Messwiderstand unmittel-bar neben der Induktivität anordnet – das heißt außerhalb der kritischen Stromschleifen an Ein- und Ausgang. Abwärts-/Aufwärtsregler für 12V/4A mit 2 MHz Schaltfrequenz und 95 % WirkungsgradDer mit 2 MHz schaltende 12V/4A-Abwärts-/Aufwärtsregler in Bild 1 erreicht einen Wirkungsgrad von 95 %. Das relativ kompakte Design nutzt 3 mm × 3 mm große MOSFETs und eine einzige, für hohe Leistung ausgelegte Induktivität. Der Temperaturanstieg dieser Wandlerschaltung ist selbst bei 48 W Leistung gering: Bei 12 V Eingangsspannung erwärmt sich kein Bauteil um mehr als 45 °C über die Umgebungstemperatur, und bei 7 V Eingangsspannung beträgt die Temperaturzunahme des heißesten Bauelements weniger als +55 °C, wenn eine herkömmliche, vierlagige Leiterplatte ohne Kühlkörper und ohne Zwangsbelüftung
60V-Abwärts-/Aufwärtsregler mit 2 MHz Schaltfrequenz regeln hohe Spannungen und Ströme mit hohem Wirkungsgrad und geringen Störaussendungen (EMI)Design Note 567 Keith Szolusha
DC/DC POWER SUPPLY
LTC3643BACKUP
CRITICALLOAD
DN565 F01
1(a)
VIN
D1
DC/DC POWER SUPPLY
LTC3643BACKUP
CRITICALLOAD
1(b)
VIN
D2
Simple Power Backup Supply for a 3.3V RailDesign Note 565
Victor Khasiev
08/17/565
Figure 1(a) and (b). Location of the Blocking Diode in the Backup System Schematic
IntroductionData loss is a concern in telecom, industrial and automotive applications where embedded systems require a dependable supply of power. Sudden power interruptions can corrupt data during read and write operations performed by hard drives and flash memory. Designers often use batteries, capacitors and supercaps to store enough energy to support criti-cal loads for a short time during a power interruption.
The LTC®3643 power backup supply allows designers to use a relatively inexpensive storage component: low cost electrolytic capacitors. In the backup or holdup supply presented here, the LTC3643 charges a storage capacitor to 40V when power is present, and discharges it to the critical load when power is inter-rupted. The load (output) voltage can be programmed to any voltage between 3V and 17V.
The LTC3643 easily fits backup solutions for 5V and 12V rails, but a 3.3V rail solution requires extra care. The minimum operating voltage of the LTC3643 is 3V, relatively close to the nominal 3.3V input volt-age level. This is too tight when a blocking diode is used to decouple the backup voltage source from noncritical circuitry as shown in Figure 1a. If D1 is a Shottky diode, its forward voltage drop—as a function of load current and temperature—can reach 0.4V to 0.5V, enough to place the voltage at the LTC3643 VIN pin below the 3V minimum. As a result, the backup supply circuit may not start up.
One possible solution is to move the diode to the input of the supplying DC/DC converter, D2, as shown in Figure 1b. Unfortunately, in this scenario, noncritical loads connected to the upstream DC/DC supply can draw power from the backup supply, leaving less energy for critical loads.
3.3V Backup Supply OperationFigure 2 shows a solution to producing a 3.3V backup supply that reserves energy for critical loads using a blocking MOSFET. The blocking diode shown in Figure 1 is replaced by Q1, a low gate threshold voltage power P-channel MOSFET.
The key to operating the backup supply in a 3.3V environment is the addition of the series RA-CA circuit. At start-up, as the input voltage rises, the current through the capacitor CA is governed by the equation IC = C • (dV/dt). This current generates a potential across RA, enough to enhance Q2, a low gate threshold voltage small signal N-channel MOSFET. As Q2 turns on, it pulls the gate of the Q1 to ground, providing an extremely low resistance path from the input voltage to the supply pins VIN of LTC3643. Once 3.3V is applied to the converter, it starts up, pulling down both the gate of Q1 and the PFO pin, and it starts charging the storage capacitor.
As the 3.3V rail reaches steady state, the IC current reduces to the point where the voltage across RA falls below the Q2 gate threshold level and Q2 turns off, no longer affecting the functionality of the backup converter. Also, the PFO pin grounds R3A, resetting the PFI pin power fail voltage level to the minimum 3V, to ensure that the converter remains operational when the input voltage source is disconnected.L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Analog Devices, Inc. All other trademarks are the property of their respective owners.
Bild 1: 12V-/4A-Auf-Abwärts-Spannungsregler mit 2 MHz Schaltfrequenz und hohem Wirkungsgrad
165k
22nF
0.1µF100V×2
0.1µF
22µF
383k
4.7µF 100k
0.47µF
59.0k2.2nF
10k
110k
10k
0.1µF
124k75k
0.1µF
1µF 1µF
L11µH
M3
M4M1
M2
1µF
10Ω
10Ω
22µF
22µFD1 D2
5mΩR1
10mΩR2
EN/UVLO
VREF
CTRL
PGOOD
BG2
BST2
TG2
INTVCC
LOADEN
FB
VOUT
ISP
ISN
SYNC/SPRD
TEST
2MHz
63V
16V×2
ISMON
PGOOD
25V
VOUT12V4ALSP LSNSW1 SW2
BST1
TG1
BG1
VIN LT8390A
LOADTG
ISMON
SS VC RT
GND
SSFM OFF
SSFM ON
25V×2
INTVCCINTVCC
INTVCC
dn567 F01
VIN6V TO 28V
(CONTINUOUS)4V TO 60V
(TRANSIENT)4.7µF100V×2
L1: WURTH 74437336010 1µHM1, M2: INFINEON BSZ065NO6LS5M3, M4: INFINEON BSZ031NE2LS5D1, D2: NEXPERIA BAT46WJR1: SUSUMU KRL3216D-M-R005-F-T5
60V 2MHz Buck-Boost Controllers Regulate High Power Voltage and Current with High Efficiency and Low EMI Design Note 567
Keith Szolusha
10/17/567
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Analog Devices, Inc. All other trademarks are the property of their respective owners.
Synchronous buck-boost controllers are versatile and highly efficient. They can produce high power as both a boost and a buck with a single inductor, keeping power supply design simple. Normally, a buck-boost controller in a high power application is operated at a standard or low switching frequency, this maximizes efficiency and avoids complications related to shoot-through and switch blanking time, which can arise in synchronous rectification at high frequencies. Nevertheless, a high frequency 2MHz buck-boost controller with a smaller inductor ensures that the EMI content resides above the AM frequency band.
The LT8390A and LT8391A buck-boost controllers are unique in that they operate at 2MHz. The high switching speed enables use of a small inductor for a compact solution size, even in high power applications.
Unlike monolithic converters, which save space with power switches inside the IC package, controllers can drive external power switches with much higher peak
currents, such as 10A. Such high peak currents would burn up the small IC packages of typical integrated converters, but external 3mm × 3mm synchronous MOSFETs can handle this power. The MOSFETs can be arranged in tight quarters with hot-loop capacitors for very low EMI. The unique peak switch current sense amplifier architecture places the sense resistor next to the power inductor, outside the critical input and output hot loops, also reducing EMI.
2MHz, 95% Efficiency, 12V, 4A Buck-BoostThe 2MHz, 12V, 4A buck-boost regulator in Figure 1 boasts efficiency to 95%. This relatively compact design uses 3mm × 3mm MOSFETs and a single high power inductor. The temperature rise for this converter is low, even at 48W. At 12V input, no component rises more than 45°C above room temperature. At 7V input, the hottest component rises less than 55°C with a
Figure 1. 2MHz 12V, 4A Buck-Boost Voltage Regulator with High Efficiency
165k
22nF
0.1µF100V×2
0.1µF
22µF
383k
4.7µF 100k
0.47µF
59.0k2.2nF
10k
110k
10k
0.1µF
124k75k
0.1µF
1µF 1µF
L11µH
M3
M4M1
M2
1µF
10Ω
10Ω
22µF
22µFD1 D2
5mΩR1
10mΩR2
EN/UVLO
VREF
CTRL
PGOOD
BG2
BST2
TG2
INTVCC
LOADEN
FB
VOUT
ISP
ISN
SYNC/SPRD
TEST
2MHz
63V
16V×2
ISMON
PGOOD
25V
VOUT12V4ALSP LSNSW1 SW2
BST1
TG1
BG1
VIN LT8390A
LOADTG
ISMON
SS VC RT
GND
SSFM OFF
SSFM ON
25V×2
INTVCCINTVCC
INTVCC
dn567 F01
VIN6V TO 28V
(CONTINUOUS)4V TO 60V
(TRANSIENT)4.7µF100V×2
L1: WURTH 74437336010 1µHM1, M2: INFINEON BSZ065NO6LS5M3, M4: INFINEON BSZ031NE2LS5D1, D2: NEXPERIA BAT46WJR1: SUSUMU KRL3216D-M-R005-F-T5
60V 2MHz Buck-Boost Controllers Regulate High Power Voltage and Current with High Efficiency and Low EMI Design Note 567
Keith Szolusha
10/17/567
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Analog Devices, Inc. All other trademarks are the property of their respective owners.
Synchronous buck-boost controllers are versatile and highly efficient. They can produce high power as both a boost and a buck with a single inductor, keeping power supply design simple. Normally, a buck-boost controller in a high power application is operated at a standard or low switching frequency, this maximizes efficiency and avoids complications related to shoot-through and switch blanking time, which can arise in synchronous rectification at high frequencies. Nevertheless, a high frequency 2MHz buck-boost controller with a smaller inductor ensures that the EMI content resides above the AM frequency band.
The LT8390A and LT8391A buck-boost controllers are unique in that they operate at 2MHz. The high switching speed enables use of a small inductor for a compact solution size, even in high power applications.
Unlike monolithic converters, which save space with power switches inside the IC package, controllers can drive external power switches with much higher peak
currents, such as 10A. Such high peak currents would burn up the small IC packages of typical integrated converters, but external 3mm × 3mm synchronous MOSFETs can handle this power. The MOSFETs can be arranged in tight quarters with hot-loop capacitors for very low EMI. The unique peak switch current sense amplifier architecture places the sense resistor next to the power inductor, outside the critical input and output hot loops, also reducing EMI.
2MHz, 95% Efficiency, 12V, 4A Buck-BoostThe 2MHz, 12V, 4A buck-boost regulator in Figure 1 boasts efficiency to 95%. This relatively compact design uses 3mm × 3mm MOSFETs and a single high power inductor. The temperature rise for this converter is low, even at 48W. At 12V input, no component rises more than 45°C above room temperature. At 7V input, the hottest component rises less than 55°C with a
Figure 1. 2MHz 12V, 4A Buck-Boost Voltage Regulator with High Efficiency
Der MCB ist ein optionaler externer Crowbar-Baustein, der an den Ausgang angeschlossen wird. Sobald die Ausgangsspannung ei-nen einstellbaren Grenzwert überschreitet (voreingestellt ist eine Ansprechschwelle von 11 % über der Nennspannung), legt der LTM4641 seinen CROWBAR-Ausgang umgehend (d. h. mit einer Reaktionszeit von maximal 500 ns) auf logisch High und schaltet seine Ausgangsspannung dauerhaft ab. Die Leistungsstufe wird hochohmig, und der obere interne MOSFET wird ebenso wie der untere abgeschaltet. Der CROWBAR-Ausgang schaltet MCB ein, wodurch die Ausgangskondensatoren entladen werden und ein weiteres Ansteigen der Ausgangsspannung unterbunden wird. Der Baustein MSP ist zwischen die eingangsseitige Spannungs-quelle (VIN) und den Eingangs-Pin (VINH) der Leistungsstufe des LTM4641 geschaltet. Der Baustein dient als rückstellbarer elekt-ronischer Stromkreisunterbrecher. Sobald die internen Schaltun-gen des LTM4641 einen Fehler wie etwa eine Überspannung am Ausgang (Output Overvoltage – OOV) registrieren, wird das Gate des MSP in einer Zeitspanne von maximal 2,6 µs entladen, wo-durch der MSP abschaltet. Damit wird die Stromversorgung vom VINH-Anschluss, dem Eingang der Leistungsstufe des LTM4641, getrennt. Die gefährliche Eingangsspannung kann auf diese Weise nicht mehr an den wertvollen Verbraucher gelangen. Zur Erzeugung des OOV-Grenzwerts nutzt der LTM4641 ferner eine unabhängige Referenzspannung, die nicht mit der Bandlücken (bandgap) -Spannung des Regelungs-IC zusammenhängt.
Bild 1 zeigt den Verlauf der CROWBAR-Spannung und von VOUT, wenn der obere MOSFET (MTOP) ausfällt und es zu einem Kurz-schluss zwischen VIN und dem Knoten SW kommt. Das CROW-BAR-Signal wechselt binnen 500 ns in den High-Status und schaltet damit den MCB ein, der den Ausgang mit der Masse verbindet. VOUT steigt zu keinem Zeitpunkt auf mehr als 110 % der Nenn-Ausgangsspannung an. Über- und Unterspannungsschutz für den EingangDer Eingang des LTM4641 ist mit einem Über- und Unterspan-nungsschutz versehen, dessen Ansprechschwellen vom Benutzer gewählt werden können (Bild 2). Der UVLO-Pin (UVLO = Undervoltage-Lockout) ist direkt mit dem invertierenden Eingang eines Komparators verbunden, dessen Ansprechschwelle 0,5 V beträgt. Wenn die Spannung am UVLO-Pin auf unter 0,5 V fällt, wird das Schalten des Wandlers unter-bunden. Sobald die Spannung an UVLO wieder über 0,5 V ansteigt, kann das Schalten wieder beginnen. Die Pins IOVRETRY und OVLO sind direkt an die nicht invertierenden Eingänge von Komparato-ren geführt, deren Ansprechschwellen ebenfalls 0,5 V betragen. Steigt die Spannung am Pin IOVRETRY auf über 0,5 V an, so wird das Schalten des Wandlers ebenfalls unterbrochen. Erst wenn die Spannung an IOVRETRY wieder mehr als 0,5 V beträgt, wird das Schalten wieder freigegeben. Das Schalten des Wandlers wird auch dann unterbunden, wenn die Spannung an OVLO die Marke
von 0,5 V übersteigt. Fällt die Spannung anschließend wieder un-ter 0,5 V, wird das Schalten jedoch erst dann wieder ermöglicht, wenn das Latch zurückgesetzt wurde. Diese drei Pins bieten zu-sätzliche Flexibilität, um das Verhalten des LTM4641 individuell einzustellen.
LINEAR TECHNOLOGY CORPORATION 2014
dn527 LT/AP 0614 111K • PRINTED IN THE USALinear Technology Corporation1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 www.linear.com
Figure 3. Efficiency Curves of LTM4641
Data Sheet Download
www.linear.com/LTM4641For applications help,
call (408) 432-1900, Ext. 3979
MCB is an external optional crowbar device residing on VOUT. If the output voltage exceeds an adjustable threshold —default value is 11% above nominal— the LTM4641 pulls its CROWBAR output logic high immediately (500ns response time, maximum) and latches off its output voltage: the power stage becomes high impedance, with both internal top and bottom MOSFETs latched off. The CROWBAR output turns on MCB, discharging the output capacitors and preventing any further positive excursion of the output voltage.
MSP is placed between the input power source (VIN) and the LTM4641's power stage input pins (VINH), and is used as a resettable electronic power-interrupt switch. When a fault condition, such as an output overvoltage (OOV) condition, is detected by the LTM4641’s internal circuitry, the gate of MSP is discharged within 2.6μs (maximum) and MSP turns off. The input source sup-ply is thus disconnected from the LTM4641’s power stage input (VINH), preventing the hazardous (input) voltage from reaching the precious load. LTM4641 also uses an independent reference voltage to gener-ate an OOV threshold, separate from the control IC’s bandgap voltage.
Figure 1 shows the CROWBAR and VOUT waveforms when the top MOSFET MTOP fails, causing a short-circuit between the VIN and SW nodes. CROWBAR goes high within 500ns and turns on MCB to short the output to ground. VOUT never exceeds 110% of the specified output voltage.
Input Overvoltage and Undervoltage ProtectionsThe LTM4641 has input undervoltage and overvoltage protections, whose trip thresholds can be set by the user. Please refer to Figure 2.
The UVLO pin feeds directly into the inverting input of a comparator whose trip threshold is 0.5V. When the UVLO pin falls below 0.5V, switching action is inhibited; when the UVLO pin exceeds 0.5V, switching action can resume. The IOVRETRY and OVLO pins each feed directly into noninverting inputs of comparators whose trip thresholds are 0.5V. When the IOVRETRY pin exceeds 0.5V, switching action is inhibited; when IOVRETRY falls below 0.5V, switching action can resume. When the OVLO pin exceeds 0.5V, switching action is inhibited; when OVLO subsequently falls below 0.5V, switching action cannot occur until the latch has
been reset. These three pins give added flexibility to tailor the behavior of the LTM4641.
Figure 2. Circuit to Set the Input UVLO, IOVRETRY and OVLO Thresholds
+
VINLVINH
LTM4641UVLO
UVLO < 0.5V = OFF
HYST PULLS UP WHENON, HYST PULLS DOWN
WHEN OFF
HYST
IOVRETRYIOVRETRY > 0.5V = OFF
OVLO > 0.5V = LATCHOFFOVLO
SGND GND
AN527 F02
RTUV
CIN(MLCC)10µF×2
CIN(BULK)
VIN
RBUV
RTOV
RMOV
RBOV
RHYST
SGND CONNECTS TO GND INTERNAL TO MODULE. KEEP SGND ROUTES/PLANES SEPARATE FROM GNDON MOTHERBOARD
EfficiencyFigure 3 below shows the efficiency curves for the LTM4641 for a typical 12V input voltage for the circuit in Figure 1. With all the protection circuits, LTM4641 can still achieve high efficiency.
ConclusionThe LTM4641 μModule regulator monitors input voltage, output voltage and temperature conditions. It can provide comprehensive electrical and thermal protection from excessive voltage stress for loads such as processors, ASICs and high end FPGAs.
OUTPUT CURRENT (A)0
EFFI
CIEN
CY (%
)
95
85
70
90
80
75
65
604 82 6
DN527 F03
1093 71 5
6.0VOUT5.0VOUT3.3VOUT2.5VOUT1.8VOUT1.5VOUT1.2VOUT1.0VOUT0.9VOUT
Bild 2. Beschaltung zum Festlegen der Ansprechschwellen für UVLO, IOVRETRY und OVLO
EffizienzBild 3 zeigt die typischen Wirkungsgradkurven des LTM4641 bei einer typischen Eingangsspannung von 12 V für die Schaltung aus Bild 1. Auch mit allen Schutzschaltungen kommt der LTM4641 auf eine hohe Effizienz.
LINEAR TECHNOLOGY CORPORATION 2014
dn527 LT/AP 0614 111K • PRINTED IN THE USALinear Technology Corporation1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 www.linear.com
Figure 3. Efficiency Curves of LTM4641
Data Sheet Download
www.linear.com/LTM4641For applications help,
call (408) 432-1900, Ext. 3979
MCB is an external optional crowbar device residing on VOUT. If the output voltage exceeds an adjustable threshold —default value is 11% above nominal— the LTM4641 pulls its CROWBAR output logic high immediately (500ns response time, maximum) and latches off its output voltage: the power stage becomes high impedance, with both internal top and bottom MOSFETs latched off. The CROWBAR output turns on MCB, discharging the output capacitors and preventing any further positive excursion of the output voltage.
MSP is placed between the input power source (VIN) and the LTM4641's power stage input pins (VINH), and is used as a resettable electronic power-interrupt switch. When a fault condition, such as an output overvoltage (OOV) condition, is detected by the LTM4641’s internal circuitry, the gate of MSP is discharged within 2.6μs (maximum) and MSP turns off. The input source sup-ply is thus disconnected from the LTM4641’s power stage input (VINH), preventing the hazardous (input) voltage from reaching the precious load. LTM4641 also uses an independent reference voltage to gener-ate an OOV threshold, separate from the control IC’s bandgap voltage.
Figure 1 shows the CROWBAR and VOUT waveforms when the top MOSFET MTOP fails, causing a short-circuit between the VIN and SW nodes. CROWBAR goes high within 500ns and turns on MCB to short the output to ground. VOUT never exceeds 110% of the specified output voltage.
Input Overvoltage and Undervoltage ProtectionsThe LTM4641 has input undervoltage and overvoltage protections, whose trip thresholds can be set by the user. Please refer to Figure 2.
The UVLO pin feeds directly into the inverting input of a comparator whose trip threshold is 0.5V. When the UVLO pin falls below 0.5V, switching action is inhibited; when the UVLO pin exceeds 0.5V, switching action can resume. The IOVRETRY and OVLO pins each feed directly into noninverting inputs of comparators whose trip thresholds are 0.5V. When the IOVRETRY pin exceeds 0.5V, switching action is inhibited; when IOVRETRY falls below 0.5V, switching action can resume. When the OVLO pin exceeds 0.5V, switching action is inhibited; when OVLO subsequently falls below 0.5V, switching action cannot occur until the latch has
been reset. These three pins give added flexibility to tailor the behavior of the LTM4641.
Figure 2. Circuit to Set the Input UVLO, IOVRETRY and OVLO Thresholds
+
VINLVINH
LTM4641UVLO
UVLO < 0.5V = OFF
HYST PULLS UP WHENON, HYST PULLS DOWN
WHEN OFF
HYST
IOVRETRYIOVRETRY > 0.5V = OFF
OVLO > 0.5V = LATCHOFFOVLO
SGND GND
AN527 F02
RTUV
CIN(MLCC)10µF×2
CIN(BULK)
VIN
RBUV
RTOV
RMOV
RBOV
RHYST
SGND CONNECTS TO GND INTERNAL TO MODULE. KEEP SGND ROUTES/PLANES SEPARATE FROM GNDON MOTHERBOARD
EfficiencyFigure 3 below shows the efficiency curves for the LTM4641 for a typical 12V input voltage for the circuit in Figure 1. With all the protection circuits, LTM4641 can still achieve high efficiency.
ConclusionThe LTM4641 μModule regulator monitors input voltage, output voltage and temperature conditions. It can provide comprehensive electrical and thermal protection from excessive voltage stress for loads such as processors, ASICs and high end FPGAs.
OUTPUT CURRENT (A)0
EFFI
CIEN
CY (%
)
95
85
70
90
80
75
65
604 82 6
DN527 F03
1093 71 5
6.0VOUT5.0VOUT3.3VOUT2.5VOUT1.8VOUT1.5VOUT1.2VOUT1.0VOUT0.9VOUT
Bild 3. Wirkungsgrad-Kennlinien des LTM4641FazitDas µModule LTM4641 überwacht die Eingangsspannung, die Ausgangsspannung und die Temperaturbedingungen. Der Bau-stein bietet Verbrauchern wie etwa Prozessoren, ASICs und an-spruchsvollen FPGAs einen umfassenden elektrischen und ther-mischen Schutz vor überhöhten Spannungen.
LINEAR TECHNOLOGY CORPORATION 2014
dn527 LT/AP 0614 111K • PRINTED IN THE USALinear Technology Corporation1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 www.linear.com
Figure 3. Efficiency Curves of LTM4641
Data Sheet Download
www.linear.com/LTM4641For applications help,
call (408) 432-1900, Ext. 3979
MCB is an external optional crowbar device residing on VOUT. If the output voltage exceeds an adjustable threshold —default value is 11% above nominal— the LTM4641 pulls its CROWBAR output logic high immediately (500ns response time, maximum) and latches off its output voltage: the power stage becomes high impedance, with both internal top and bottom MOSFETs latched off. The CROWBAR output turns on MCB, discharging the output capacitors and preventing any further positive excursion of the output voltage.
MSP is placed between the input power source (VIN) and the LTM4641's power stage input pins (VINH), and is used as a resettable electronic power-interrupt switch. When a fault condition, such as an output overvoltage (OOV) condition, is detected by the LTM4641’s internal circuitry, the gate of MSP is discharged within 2.6μs (maximum) and MSP turns off. The input source sup-ply is thus disconnected from the LTM4641’s power stage input (VINH), preventing the hazardous (input) voltage from reaching the precious load. LTM4641 also uses an independent reference voltage to gener-ate an OOV threshold, separate from the control IC’s bandgap voltage.
Figure 1 shows the CROWBAR and VOUT waveforms when the top MOSFET MTOP fails, causing a short-circuit between the VIN and SW nodes. CROWBAR goes high within 500ns and turns on MCB to short the output to ground. VOUT never exceeds 110% of the specified output voltage.
Input Overvoltage and Undervoltage ProtectionsThe LTM4641 has input undervoltage and overvoltage protections, whose trip thresholds can be set by the user. Please refer to Figure 2.
The UVLO pin feeds directly into the inverting input of a comparator whose trip threshold is 0.5V. When the UVLO pin falls below 0.5V, switching action is inhibited; when the UVLO pin exceeds 0.5V, switching action can resume. The IOVRETRY and OVLO pins each feed directly into noninverting inputs of comparators whose trip thresholds are 0.5V. When the IOVRETRY pin exceeds 0.5V, switching action is inhibited; when IOVRETRY falls below 0.5V, switching action can resume. When the OVLO pin exceeds 0.5V, switching action is inhibited; when OVLO subsequently falls below 0.5V, switching action cannot occur until the latch has
been reset. These three pins give added flexibility to tailor the behavior of the LTM4641.
Figure 2. Circuit to Set the Input UVLO, IOVRETRY and OVLO Thresholds
+
VINLVINH
LTM4641UVLO
UVLO < 0.5V = OFF
HYST PULLS UP WHENON, HYST PULLS DOWN
WHEN OFF
HYST
IOVRETRYIOVRETRY > 0.5V = OFF
OVLO > 0.5V = LATCHOFFOVLO
SGND GND
AN527 F02
RTUV
CIN(MLCC)10µF×2
CIN(BULK)
VIN
RBUV
RTOV
RMOV
RBOV
RHYST
SGND CONNECTS TO GND INTERNAL TO MODULE. KEEP SGND ROUTES/PLANES SEPARATE FROM GNDON MOTHERBOARD
EfficiencyFigure 3 below shows the efficiency curves for the LTM4641 for a typical 12V input voltage for the circuit in Figure 1. With all the protection circuits, LTM4641 can still achieve high efficiency.
ConclusionThe LTM4641 μModule regulator monitors input voltage, output voltage and temperature conditions. It can provide comprehensive electrical and thermal protection from excessive voltage stress for loads such as processors, ASICs and high end FPGAs.
OUTPUT CURRENT (A)0
EFFI
CIEN
CY (%
)
95
85
70
90
80
75
65
604 82 6
DN527 F03
1093 71 5
6.0VOUT5.0VOUT3.3VOUT2.5VOUT1.8VOUT1.5VOUT1.2VOUT1.0VOUT0.9VOUT
LINEAR TECHNOLOGY CORPORATION 2014
dn527 LT/AP 0614 111K • PRINTED IN THE USALinear Technology Corporation1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 www.linear.com
Figure 3. Efficiency Curves of LTM4641
Data Sheet Download
www.linear.com/LTM4641For applications help,
call (408) 432-1900, Ext. 3979
MCB is an external optional crowbar device residing on VOUT. If the output voltage exceeds an adjustable threshold —default value is 11% above nominal— the LTM4641 pulls its CROWBAR output logic high immediately (500ns response time, maximum) and latches off its output voltage: the power stage becomes high impedance, with both internal top and bottom MOSFETs latched off. The CROWBAR output turns on MCB, discharging the output capacitors and preventing any further positive excursion of the output voltage.
MSP is placed between the input power source (VIN) and the LTM4641's power stage input pins (VINH), and is used as a resettable electronic power-interrupt switch. When a fault condition, such as an output overvoltage (OOV) condition, is detected by the LTM4641’s internal circuitry, the gate of MSP is discharged within 2.6μs (maximum) and MSP turns off. The input source sup-ply is thus disconnected from the LTM4641’s power stage input (VINH), preventing the hazardous (input) voltage from reaching the precious load. LTM4641 also uses an independent reference voltage to gener-ate an OOV threshold, separate from the control IC’s bandgap voltage.
Figure 1 shows the CROWBAR and VOUT waveforms when the top MOSFET MTOP fails, causing a short-circuit between the VIN and SW nodes. CROWBAR goes high within 500ns and turns on MCB to short the output to ground. VOUT never exceeds 110% of the specified output voltage.
Input Overvoltage and Undervoltage ProtectionsThe LTM4641 has input undervoltage and overvoltage protections, whose trip thresholds can be set by the user. Please refer to Figure 2.
The UVLO pin feeds directly into the inverting input of a comparator whose trip threshold is 0.5V. When the UVLO pin falls below 0.5V, switching action is inhibited; when the UVLO pin exceeds 0.5V, switching action can resume. The IOVRETRY and OVLO pins each feed directly into noninverting inputs of comparators whose trip thresholds are 0.5V. When the IOVRETRY pin exceeds 0.5V, switching action is inhibited; when IOVRETRY falls below 0.5V, switching action can resume. When the OVLO pin exceeds 0.5V, switching action is inhibited; when OVLO subsequently falls below 0.5V, switching action cannot occur until the latch has
been reset. These three pins give added flexibility to tailor the behavior of the LTM4641.
Figure 2. Circuit to Set the Input UVLO, IOVRETRY and OVLO Thresholds
+
VINLVINH
LTM4641UVLO
UVLO < 0.5V = OFF
HYST PULLS UP WHENON, HYST PULLS DOWN
WHEN OFF
HYST
IOVRETRYIOVRETRY > 0.5V = OFF
OVLO > 0.5V = LATCHOFFOVLO
SGND GND
AN527 F02
RTUV
CIN(MLCC)10µF×2
CIN(BULK)
VIN
RBUV
RTOV
RMOV
RBOV
RHYST
SGND CONNECTS TO GND INTERNAL TO MODULE. KEEP SGND ROUTES/PLANES SEPARATE FROM GNDON MOTHERBOARD
EfficiencyFigure 3 below shows the efficiency curves for the LTM4641 for a typical 12V input voltage for the circuit in Figure 1. With all the protection circuits, LTM4641 can still achieve high efficiency.
ConclusionThe LTM4641 μModule regulator monitors input voltage, output voltage and temperature conditions. It can provide comprehensive electrical and thermal protection from excessive voltage stress for loads such as processors, ASICs and high end FPGAs.
OUTPUT CURRENT (A)0
EFFI
CIEN
CY (%
)
95
85
70
90
80
75
65
604 82 6
DN527 F03
1093 71 5
6.0VOUT5.0VOUT3.3VOUT2.5VOUT1.8VOUT1.5VOUT1.2VOUT1.0VOUT0.9VOUT
Bei technischen Fragen,Telefon +49 89 96 24 55 0
verwendet wird. Der Wandler kommt mit kurzzeitigen Einbrüchen der Eingangsspannung auf 4 V bei 4 A Laststrom zurecht oder kann bei 2 A Laststrom dauerhaft mit 4 V Eingangsspannung betrieben werden, was einer Leistung von ca. 25 W entspricht. Die hohe Schaltfrequenz (600 kHz bis 2 MHz) des LT8390A unterschei-det diesen Baustein von anderen Reglern mit vier Schaltern. Ebenso wie sein für niedrigere Schaltfrequenzen ausgelegter Verwandter LT8390 weist er eine ganze Reihe bemerkenswerter Eigenschaften auf, wie etwa ein PGOOD-Flag, Kurzschlussschutz und einen flexiblen Strom-begrenzungs-Messwiderstand zur Limitierung des Ausgangs- oder Ein-schalt (Inrush)-Stroms. Mit seiner zur Senkung des EMI-Aufkommens dienenden Spread-Spectrum-Frequenzmodulation (SSFM) eignet er sich ideal für Automotive-Anwendungen. Abwärts-/Aufwärts-LED-Treiber mit 2 MHz Schaltfrequenz und ge-ringen EMI-Effekten für Automotive-AnwendungenDer LT8391A ist das als LED-Treiber konzipierte, ebenfalls mit 2 MHz betriebene Gegenstück zum LT8390A. Der Hauptunterschied zwi-schen beiden ist, dass der LT8391A mit PWM-Dimmfunktionen und einer Funktion zur Erkennung von Unterbrechungen im LED-Stromkreis ausgestattet ist. Mithilfe des Messwiderstands am Ausgang wird der Strom durch eine LED-Kette geregelt, deren Spannung im Bereich der Eingangsspannung liegen kann (z. B. 9 V bis 16 V bei einer Autobat-terie). Die Eingangsspannung darf bei Kaltstarts bis auf 4 V absinken, und kurzzeitige Spannungsspitzen von 60 V am Eingang sind ebenfalls zulässig. Der LT8391A bietet ein PWM-Dimmungsverhältnis von bis zu 2.000:1 bei 120 Hz. Mit seinem eingebauten PWM-Dimmungsgenerator, der ohne externen Takt auskommt, ermöglicht er eine präzise Dimmung im Verhältnis 128:1. Der in Bild 2 gezeigte, mit 2 MHz schaltende LED-Treiber LT8391A ist für Kfz-Frontscheinwerfer optimiert. Er nutzt AEC-Q100-qualifizierte Bautei-le und entspricht der Norm CISPR 25 Klasse 5 für gestrahlte elektromagnetische Störaussendungen. Die SSFM-Technik wirkt EMI-re-
duzierend und sorgt für einen flimmerfreien Betrieb bei gleichzeitiger PWM-Dimmung. Das kompakte Design kommt mit einer kleinen Induktivität und be-sonders kompakten EMI-Filtern am Ein- und Ausgang aus. Die Ein-gangsspannung kann zwischen 4 V und 60 V betragen. Die vier Syn-chron-MOSFETs lassen sich bei Bedarf durch zwei Doppel-MOSFETs ersetzen, um den Bauteileaufwand zu verringern. Die Schaltung kommt auf einen Wirkungsgrad von 93 %. Das FAULT-Flag signalisiert Kurz-schlüsse und unterbrochene LED-Verbindungen, mit denen die Schal-tung problemlos fertig wird. FazitDie mit 2 MHz Schaltfrequenz betriebenen 60V-Abwärts-/Aufwärtsregler LT8390A und LT8391A können bei wenig Platzaufwand hohe Spannun-gen und Ströme regeln. Die auf geringe elektromagnetische Störaus-sendungen ausgerichtete Architektur und die SSFM-Technik machen die Bausteine zur idealen Wahl für Anwendungen, in denen es auf geringe EMI-Effekte ankommt.
INPUT = 500mVP-P
FREQUENCY (kHz)0.1 1 10
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
THD
+ NO
ISE
(%)
DN563 F02
50Ω100Ω300ΩNO LOAD INPUT AT 1kHz
NO LOAD300Ω100Ω50Ω
AUDIO INPUT AMPLITUDE (V)0.001 0.01 0.1 1 20
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
THD
+ NO
ISE
(%)
DN563 F03
Data Sheet Download
www.linear.com/LTC6261For applications help,
call (408) 432-1900, Ext. 3409
With 500mVP-P input, the output is 1.5VP-P, or 0.75V max, or 0.53VRMS. With 50Ω, 500mV input leads to approximately 5.6mW delivered power. At 1VP-P input, the circuit delivers 22.5mW. Note that it helps that the LTC6261 output can swing close to rail-to-rail with load.
The first build of this circuit in the lab produced a significant tone at a few hundred Hz. It turned out that the positive input was not well grounded as an “AC ground” over all frequencies because the voltage was not strongly pegged. The need to peg the voltage arises when using a single supply rather than a dual supply. With a single supply, VM is not ground, but rather a mid-rail voltage created to enable inverting topologies to work properly. The resistor divider that creates VM has large resistance values (for example, two 470k in series) to minimize additional supply cur-rent. A large capacitor ensures a strong ground at low frequencies. Indeed, the addition of a large capacitor (1µF, which forms a pole with the 470k resistors in parallel) eliminated the mysterious distortion tone.
Figure 2. LTC6262 Bridge Driver THD and Noise with Different Loads vs Frequency
Figure 3. LTC6262 Bridge Driver THD and Noise with Different Loads vs Amplitude at 1kHz
Despite the low quiescent current, this driver delivers low distortion to a headphone load. At high enough amplitude, distortion increases dramatically as the op amp output clips. Clipping occurs sooner with more loading as the output transistors start to run out of current gain.
One significant concern in a portable device is bat-tery drain. Music played loudly, or listeners’ musical choices affect the rate of battery drain. The end-use of a device is out of the designer’s control. Quiescent current, though, is not. Because much of a device’s time may be spent idle, quiescent current is significant, as it drains batteries continuously. The LTC6261’s low quiescent current increases battery discharge time.
ConclusionThe applications shown here take advantage of a unique combination of features available in the LTC6261 op amp family. The low quiescent current of these devices does not diminish their ability to perform at levels usually reserved for more power hungry parts. Rail-to-rail input and output, shutdown, and choice of package are features that add to their versatility.
DN563 LT/TP 0617 71K • PRINTED IN THE USA© LINEAR TECHNOLOGY CORPORATION 2017
Bild 2: Dieser 16V/1,5A-Auf-Abwärts-LED-Treiber für Automotive-Anwendungen erfüllt die Bedingungen der EMI-Norm CISPR 25 Klasse 5
CONTINUOUS OPERATION WITH HIGHEST COMPONENT TEMPERATURE BELOW 90°C (TA = 25°C)
INPUT VOLTAGE (V)0 5 10 15 20 25 30 35 40
50
60
70
80
90
100
EFFI
CIEN
CY (%
)
dn567 F03
IOUT = 2A
IOUT = 4A
165k
22nF
4.7µF
0.1µF22µF
383k
4.7µF100k
0.47µF
113k
90.9k
59.0k3.3nF
4.7k
1M54.9k
10µF
100k
0.1µF
1µF
1µF
L12.2µH
M3
M4M1
M2
D1 D2
6mΩR1
56mΩ
M5D3
300k488Hz
FB2
0.1µF
FB1
4.7µF
0.1µF
10Ω
D5
10Ω
D4
EN/UVLO
VREF
CTRL1
FAULT
BG2
BST2
TG2
INTVCC
FB
VOUT
ISP
ISNSYNC/SPRD
VIN6V TO 40V
(CONTINUOUS)4V TO 60V
(TRANSIENT)
2MHz
63V100V×2+0.1µF×2
25V×2+0.1µF×2
FAULT
LSP LSNSW1 SW2BST1
TG1
BG1
VIN
LT8391A
SS VC RT
GND
SSFM OFF
SSFM ON
INTVCCINTVCC
INTVCC
PWMTG
PWM
RPCTRL2
ANALOG DIM
PWM DIM
100V×2
16V1.5ALEDs
INPUT EMI FILTER
OUTPUT EMIFILTER
dn567 F02
5.1Ω
5.1Ω
INTERNAL PWM
L1: COILCRAFT XAL5030-222MEBM1, M2: NEXPERIA BUK9M42-60EM3, M4: INFINEON IPZ40N04S5L-7R4M5: NEXPERIA PMV50EPEAD1, D2: NEXPERIA BAT46WJD3: NEXPERIA PMEG3010EBD4, D5: NEXPERIA PMEG2010AEBFB1: 2× PARALLEL TDK MPZ2012S221ATD25FB2: 2× PARALLEL TDK MPZ2012S102ATD25R1: SUSUMU KRL3216D-C-R006-F
© LINEAR TECHNOLOGY CORPORATION 2017DN567 LT/AP 1017 71K • PRINTED IN THE USA
Data Sheet Download
www.linear.com/LT8390AFor applications help,
call (408) 432-1900, Ext. 3801
Figure 2. Low EMI 16V, 1.5A Automotive Buck-Boost LED Driver Passes CISPR 25 Class 5 EMI
standard 4-layer PCB and no heat sink or airflow. This converter handles short input transients down to 4V at 4A load, or runs continuously at 4V input with 2A of load (~25W).
The LT8390A’s high switching frequency (600kHz to 2MHz) distinguishes it from the field of 4-switch con-trollers. It also has a variety of notable features like its lower frequency cousin, the LT8390. It has a PGOOD flag, short-circuit protection, and a flexible current-limiting sense resistor for output or inrush current restrictions. Its spread spectrum frequency modulation (SSFM) for low EMI makes it ideal for automotive applications.
2MHz Low EMI Automotive Buck-Boost LED DriverThe LT8391A is a 2MHz LED driver counterpart of the LT8390A. The main difference is that LT8391A includes LED driver PWM dimming features and open LED fault protection. The output sense resistor controls current through a string of LEDs whose voltage may lie within the input voltage range, such as the 9V to 16V car battery. It can run down to 4V cold crank and can withstand up to 60V input transients. LT8391A provides up to 2000:1 PWM dimming ratio at 120Hz and it can use its internal PWM dimming generator (no external clock required) for up to 128:1 accurate dimming.
The 2MHz LT8391A LED driver shown in Figure 1 is optimized for automotive headlights. It uses AEC-Q100
components and meets CISPR 25 Class 5 radiated EMI standards. SSFM reduces EMI, and also runs flicker-free simultaneously with PWM dimming.
This compact design features a small inductor and especially small input and output EMI filters. It can run down to 4V and up to 60V. The four synchronous MOSFETs shown can be replaced with two dual MOSFETs for reduced component count when needed. It reaches 93% efficiency. The FAULT flag reports short-circuit and open LED conditions, which are handled with ease.
ConclusionThe LT8390A and LT8391A 2MHz 60V buck-boost controllers can regulate high power voltage and cur-rent in compact spaces. The low EMI architecture and SSFM feature make these ideal for low EMI applications.
Figure 3. LT8390A Efficiency of Figure 1
CONTINUOUS OPERATION WITH HIGHEST COMPONENT TEMPERATURE BELOW 90°C (TA = 25°C)
INPUT VOLTAGE (V)0 5 10 15 20 25 30 35 40
50
60
70
80
90
100EF
FICI
ENCY
(%)
dn567 F03
IOUT = 2A
IOUT = 4A
165k
22nF
4.7µF
0.1µF22µF
383k
4.7µF100k
0.47µF
113k
90.9k
59.0k3.3nF
4.7k
1M54.9k
10µF
100k
0.1µF
1µF
1µF
L12.2µH
M3
M4M1
M2
D1 D2
6mΩR1
56mΩ
M5D3
300k488Hz
FB2
0.1µF
FB1
4.7µF
0.1µF
10Ω
D5
10Ω
D4
EN/UVLO
VREF
CTRL1
FAULT
BG2
BST2
TG2
INTVCC
FB
VOUT
ISP
ISNSYNC/SPRD
VIN6V TO 40V
(CONTINUOUS)4V TO 60V
(TRANSIENT)
2MHz
63V100V×2+0.1µF×2
25V×2+0.1µF×2
FAULT
LSP LSNSW1 SW2BST1
TG1
BG1
VIN
LT8391A
SS VC RT
GND
SSFM OFF
SSFM ON
INTVCCINTVCC
INTVCC
PWMTG
PWM
RPCTRL2
ANALOG DIM
PWM DIM
100V×2
16V1.5ALEDs
INPUT EMI FILTER
OUTPUT EMIFILTER
dn567 F02
5.1Ω
5.1Ω
INTERNAL PWM
L1: COILCRAFT XAL5030-222MEBM1, M2: NEXPERIA BUK9M42-60EM3, M4: INFINEON IPZ40N04S5L-7R4M5: NEXPERIA PMV50EPEAD1, D2: NEXPERIA BAT46WJD3: NEXPERIA PMEG3010EBD4, D5: NEXPERIA PMEG2010AEBFB1: 2× PARALLEL TDK MPZ2012S221ATD25FB2: 2× PARALLEL TDK MPZ2012S102ATD25R1: SUSUMU KRL3216D-C-R006-F
© LINEAR TECHNOLOGY CORPORATION 2017DN567 LT/AP 1017 71K • PRINTED IN THE USA
Data Sheet Download
www.linear.com/LT8390AFor applications help,
call (408) 432-1900, Ext. 3801
Figure 2. Low EMI 16V, 1.5A Automotive Buck-Boost LED Driver Passes CISPR 25 Class 5 EMI
standard 4-layer PCB and no heat sink or airflow. This converter handles short input transients down to 4V at 4A load, or runs continuously at 4V input with 2A of load (~25W).
The LT8390A’s high switching frequency (600kHz to 2MHz) distinguishes it from the field of 4-switch con-trollers. It also has a variety of notable features like its lower frequency cousin, the LT8390. It has a PGOOD flag, short-circuit protection, and a flexible current-limiting sense resistor for output or inrush current restrictions. Its spread spectrum frequency modulation (SSFM) for low EMI makes it ideal for automotive applications.
2MHz Low EMI Automotive Buck-Boost LED DriverThe LT8391A is a 2MHz LED driver counterpart of the LT8390A. The main difference is that LT8391A includes LED driver PWM dimming features and open LED fault protection. The output sense resistor controls current through a string of LEDs whose voltage may lie within the input voltage range, such as the 9V to 16V car battery. It can run down to 4V cold crank and can withstand up to 60V input transients. LT8391A provides up to 2000:1 PWM dimming ratio at 120Hz and it can use its internal PWM dimming generator (no external clock required) for up to 128:1 accurate dimming.
The 2MHz LT8391A LED driver shown in Figure 1 is optimized for automotive headlights. It uses AEC-Q100
components and meets CISPR 25 Class 5 radiated EMI standards. SSFM reduces EMI, and also runs flicker-free simultaneously with PWM dimming.
This compact design features a small inductor and especially small input and output EMI filters. It can run down to 4V and up to 60V. The four synchronous MOSFETs shown can be replaced with two dual MOSFETs for reduced component count when needed. It reaches 93% efficiency. The FAULT flag reports short-circuit and open LED conditions, which are handled with ease.
ConclusionThe LT8390A and LT8391A 2MHz 60V buck-boost controllers can regulate high power voltage and cur-rent in compact spaces. The low EMI architecture and SSFM feature make these ideal for low EMI applications.
Figure 3. LT8390A Efficiency of Figure 1 Bild 3: Wirkungsgrad des LT8390A in der Schaltung aus Bild 1
CONTINUOUS OPERATION WITH HIGHEST COMPONENT TEMPERATURE BELOW 90°C (TA = 25°C)
INPUT VOLTAGE (V)0 5 10 15 20 25 30 35 40
50
60
70
80
90
100EF
FICI
ENCY
(%)
dn567 F03
IOUT = 2A
IOUT = 4A
165k
22nF
4.7µF
0.1µF22µF
383k
4.7µF100k
0.47µF
113k
90.9k
59.0k3.3nF
4.7k
1M54.9k
10µF
100k
0.1µF
1µF
1µF
L12.2µH
M3
M4M1
M2
D1 D2
6mΩR1
56mΩ
M5D3
300k488Hz
FB2
0.1µF
FB1
4.7µF
0.1µF
10Ω
D5
10Ω
D4
EN/UVLO
VREF
CTRL1
FAULT
BG2
BST2
TG2
INTVCC
FB
VOUT
ISP
ISNSYNC/SPRD
VIN6V TO 40V
(CONTINUOUS)4V TO 60V
(TRANSIENT)
2MHz
63V100V×2+0.1µF×2
25V×2+0.1µF×2
FAULT
LSP LSNSW1 SW2BST1
TG1
BG1
VIN
LT8391A
SS VC RT
GND
SSFM OFF
SSFM ON
INTVCCINTVCC
INTVCC
PWMTG
PWM
RPCTRL2
ANALOG DIM
PWM DIM
100V×2
16V1.5ALEDs
INPUT EMI FILTER
OUTPUT EMIFILTER
dn567 F02
5.1Ω
5.1Ω
INTERNAL PWM
L1: COILCRAFT XAL5030-222MEBM1, M2: NEXPERIA BUK9M42-60EM3, M4: INFINEON IPZ40N04S5L-7R4M5: NEXPERIA PMV50EPEAD1, D2: NEXPERIA BAT46WJD3: NEXPERIA PMEG3010EBD4, D5: NEXPERIA PMEG2010AEBFB1: 2× PARALLEL TDK MPZ2012S221ATD25FB2: 2× PARALLEL TDK MPZ2012S102ATD25R1: SUSUMU KRL3216D-C-R006-F
© LINEAR TECHNOLOGY CORPORATION 2017DN567 LT/AP 1017 71K • PRINTED IN THE USA
Data Sheet Download
www.linear.com/LT8390AFor applications help,
call (408) 432-1900, Ext. 3801
Figure 2. Low EMI 16V, 1.5A Automotive Buck-Boost LED Driver Passes CISPR 25 Class 5 EMI
standard 4-layer PCB and no heat sink or airflow. This converter handles short input transients down to 4V at 4A load, or runs continuously at 4V input with 2A of load (~25W).
The LT8390A’s high switching frequency (600kHz to 2MHz) distinguishes it from the field of 4-switch con-trollers. It also has a variety of notable features like its lower frequency cousin, the LT8390. It has a PGOOD flag, short-circuit protection, and a flexible current-limiting sense resistor for output or inrush current restrictions. Its spread spectrum frequency modulation (SSFM) for low EMI makes it ideal for automotive applications.
2MHz Low EMI Automotive Buck-Boost LED DriverThe LT8391A is a 2MHz LED driver counterpart of the LT8390A. The main difference is that LT8391A includes LED driver PWM dimming features and open LED fault protection. The output sense resistor controls current through a string of LEDs whose voltage may lie within the input voltage range, such as the 9V to 16V car battery. It can run down to 4V cold crank and can withstand up to 60V input transients. LT8391A provides up to 2000:1 PWM dimming ratio at 120Hz and it can use its internal PWM dimming generator (no external clock required) for up to 128:1 accurate dimming.
The 2MHz LT8391A LED driver shown in Figure 1 is optimized for automotive headlights. It uses AEC-Q100
components and meets CISPR 25 Class 5 radiated EMI standards. SSFM reduces EMI, and also runs flicker-free simultaneously with PWM dimming.
This compact design features a small inductor and especially small input and output EMI filters. It can run down to 4V and up to 60V. The four synchronous MOSFETs shown can be replaced with two dual MOSFETs for reduced component count when needed. It reaches 93% efficiency. The FAULT flag reports short-circuit and open LED conditions, which are handled with ease.
ConclusionThe LT8390A and LT8391A 2MHz 60V buck-boost controllers can regulate high power voltage and cur-rent in compact spaces. The low EMI architecture and SSFM feature make these ideal for low EMI applications.
Figure 3. LT8390A Efficiency of Figure 1
CONTINUOUS OPERATION WITH HIGHEST COMPONENT TEMPERATURE BELOW 90°C (TA = 25°C)
INPUT VOLTAGE (V)0 5 10 15 20 25 30 35 40
50
60
70
80
90
100EF
FICI
ENCY
(%)
dn567 F03
IOUT = 2A
IOUT = 4A
165k
22nF
4.7µF
0.1µF22µF
383k
4.7µF100k
0.47µF
113k
90.9k
59.0k3.3nF
4.7k
1M54.9k
10µF
100k
0.1µF
1µF
1µF
L12.2µH
M3
M4M1
M2
D1 D2
6mΩR1
56mΩ
M5D3
300k488Hz
FB2
0.1µF
FB1
4.7µF
0.1µF
10Ω
D5
10Ω
D4
EN/UVLO
VREF
CTRL1
FAULT
BG2
BST2
TG2
INTVCC
FB
VOUT
ISP
ISNSYNC/SPRD
VIN6V TO 40V
(CONTINUOUS)4V TO 60V
(TRANSIENT)
2MHz
63V100V×2+0.1µF×2
25V×2+0.1µF×2
FAULT
LSP LSNSW1 SW2BST1
TG1
BG1
VIN
LT8391A
SS VC RT
GND
SSFM OFF
SSFM ON
INTVCCINTVCC
INTVCC
PWMTG
PWM
RPCTRL2
ANALOG DIM
PWM DIM
100V×2
16V1.5ALEDs
INPUT EMI FILTER
OUTPUT EMIFILTER
dn567 F02
5.1Ω
5.1Ω
INTERNAL PWM
L1: COILCRAFT XAL5030-222MEBM1, M2: NEXPERIA BUK9M42-60EM3, M4: INFINEON IPZ40N04S5L-7R4M5: NEXPERIA PMV50EPEAD1, D2: NEXPERIA BAT46WJD3: NEXPERIA PMEG3010EBD4, D5: NEXPERIA PMEG2010AEBFB1: 2× PARALLEL TDK MPZ2012S221ATD25FB2: 2× PARALLEL TDK MPZ2012S102ATD25R1: SUSUMU KRL3216D-C-R006-F
© LINEAR TECHNOLOGY CORPORATION 2017DN567 LT/AP 1017 71K • PRINTED IN THE USA
Data Sheet Download
www.linear.com/LT8390AFor applications help,
call (408) 432-1900, Ext. 3801
Figure 2. Low EMI 16V, 1.5A Automotive Buck-Boost LED Driver Passes CISPR 25 Class 5 EMI
standard 4-layer PCB and no heat sink or airflow. This converter handles short input transients down to 4V at 4A load, or runs continuously at 4V input with 2A of load (~25W).
The LT8390A’s high switching frequency (600kHz to 2MHz) distinguishes it from the field of 4-switch con-trollers. It also has a variety of notable features like its lower frequency cousin, the LT8390. It has a PGOOD flag, short-circuit protection, and a flexible current-limiting sense resistor for output or inrush current restrictions. Its spread spectrum frequency modulation (SSFM) for low EMI makes it ideal for automotive applications.
2MHz Low EMI Automotive Buck-Boost LED DriverThe LT8391A is a 2MHz LED driver counterpart of the LT8390A. The main difference is that LT8391A includes LED driver PWM dimming features and open LED fault protection. The output sense resistor controls current through a string of LEDs whose voltage may lie within the input voltage range, such as the 9V to 16V car battery. It can run down to 4V cold crank and can withstand up to 60V input transients. LT8391A provides up to 2000:1 PWM dimming ratio at 120Hz and it can use its internal PWM dimming generator (no external clock required) for up to 128:1 accurate dimming.
The 2MHz LT8391A LED driver shown in Figure 1 is optimized for automotive headlights. It uses AEC-Q100
components and meets CISPR 25 Class 5 radiated EMI standards. SSFM reduces EMI, and also runs flicker-free simultaneously with PWM dimming.
This compact design features a small inductor and especially small input and output EMI filters. It can run down to 4V and up to 60V. The four synchronous MOSFETs shown can be replaced with two dual MOSFETs for reduced component count when needed. It reaches 93% efficiency. The FAULT flag reports short-circuit and open LED conditions, which are handled with ease.
ConclusionThe LT8390A and LT8391A 2MHz 60V buck-boost controllers can regulate high power voltage and cur-rent in compact spaces. The low EMI architecture and SSFM feature make these ideal for low EMI applications.
Figure 3. LT8390A Efficiency of Figure 1