1®

IVC102

IIN

VB

1

2

3

4

5

6

11 12 13

DigitalGround

AnalogGround

Logic Low closes switches

9

10

14

VO

V+

V–

S1 S2

IonizationChamber

Photodiode

60pF

30pF

10pF

S1

C1

C2

C3

S2

International Airport Industrial Park • Mailing Address: PO Box 11400 • Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd. • Tucson, AZ 85706Tel: (520) 746-1111 • Twx: 910-952-1111 • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132

®

PRECISION SWITCHED INTEGRATORTRANSIMPEDANCE AMPLIFIER

APPLICATIONS● PRECISION LOW CURRENT MEASUREMENT

● PHOTODIODE MEASUREMENTS

● IONIZATION CHAMBER MEASUREMENTS● CURRENT/CHARGE-OUTPUT SENSORS

● LEAKAGE CURRENT MEASUREMENT

IVC102

FEATURES● ON-CHIP INTEGRATING CAPACITORS

● GAIN PROGRAMMED BY TIMING● LOW INPUT BIAS CURRENT: 750fA max

● LOW NOISE

● LOW SWITCH CHARGE INJECTION

● FAST PULSE INTEGRATION

● LOW NONLINEARITY: 0.005% typ

● 14-PIN DIP, SO-14 SURFACE MOUNT

DESCRIPTIONThe IVC102 is a precision integrating amplifier withFET op amp, integrating capacitors, and low leakageFET switches. It integrates low-level input current fora user-determined period, storing the resulting voltageon the integrating capacitor. The output voltage can beheld for accurate measurement. The IVC102 providesa precision, lower noise alternative to conventionaltransimpedance op amp circuits that require a veryhigh value feedback resistor.

The IVC102 is ideal for amplifying low-level sensorcurrents from photodiodes and ionization chambers.The input signal current can be positive or negative.

TTL/CMOS-compatible timing inputs control the inte-gration period, hold and reset functions to set theeffective transimpedance gain and to reset (discharge)the integrator capacitor.

Package options include 14-Pin plastic DIP and SO-14surface-mount packages. Both are specified for the–40°C to 85°C industrial temperature range.

© 1996 Burr-Brown Corporation PDS-1329A Printed in U.S.A. June, 1996

0V

Hold Integrate Hold Reset

Positive or NegativeSignal Integration

S1

S2

IIN(t)VO =–1 ∫ dtCINT

SBFS009

2®

IVC102

The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN assumesno responsibility for the use of this information, and all use of such information shall be entirely at the user’s own risk. Prices and specifications are subject to changewithout notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not authorize or warrantany BURR-BROWN product for use in life support devices and/or systems.

NOTES: (1) Standard test timing: 1ms integration, 200µs hold, 100µs reset. (2) Hold mode output voltage after 1ms integration of zero input current. Includes opamp offset voltage, integration of input error current and switch charge injection effects.

SPECIFICATIONSAt TA = +25°C, VS = ±15V, RL = 2kΩ, CINT = C1 + C2 + C3, 1ms integration period(1), unless otherwise specified.

IVC102P, U

PARAMETER CONDITIONS MIN TYP MAX UNITS

TRANSFER FUNCTION VO = –(IIN)(TINT)/CINTGain Error CINT = C1 + C2 + C3 ±5 +25/–17 %

vs Temperature ±25 ppm/°CNonlinearity VO = ±10V ±0.005 %Input Current Range ±100 µAOffset Voltage(2) IIN = 0, CIN = 50pF –5 ±20 mV

vs Temperature ±30 µV/°Cvs Power Supply VS = +4.75/–10 to +18/–18V 150 750 µV/V

Droop Rate, Hold Mode –1 nV/µs

OP AMPInput Bias Current S1, S2 Open –100 ±750 fA

vs Temperature See Typical CurveOffset Voltage (Op Amp VOS) ±0.5 ±5 mV

vs Temperature ±5 µV/°Cvs Power Supply VS = +4.75/–10 to +18/–18V 10 100 µV/V

Noise Voltage f = 1kHz 10 nV/√Hz

INTEGRATION CAPACITORSC1 + C2 + C3 80 100 120 pF

vs Temperature ±25 ppm/°CC1 10 pFC2 30 pFC3 60 pF

OUTPUTVoltage Range, Positive RL = 2kΩ (V+)–3 (V+)–1.3 V

Negative RL = 2kΩ (V–)+3 (V–)+2.6 VShort-Circuit Current ±20 mACapacitive Load Drive 500 pFNoise Voltage See Typical Curve

DYNAMIC CHARACTERISTICOp Amp Gain-Bandwidth 2 MHzOp Amp Slew Rate 3 V/µsReset

Slew Rate 3 V/µsSettling Time, 0.01% 10V Step 6 µs

DIGITAL INPUTS (TTL/CMOS Compatible)VIH (referred to digital ground) (Logic High) 2 5.5 VVIL (referred to digital ground) (Logic Low) –0.5 0.8 VIIH VIH = 5V 2 µAIIL VIL = 0V 0 µASwitching Time 100 ns

POWER SUPPLYVoltage Range: Positive +4.75 +15 +18 V

Negative –10 –15 –18 VCurrent: Positive 4.1 5.5 mA

Negative –1.6 –2.2 mAAnalog Ground –0.2 mADigital Ground –2.3 mA

TEMPERATURE RANGEOperating Range –40 85 °CStorage –55 125 °CThermal Resistance, θJA

DIP 100 °C/WSO-14 150 °C/W

3®

IVC102

ELECTROSTATICDISCHARGE SENSITIVITY

This integrated circuit can be damaged by ESD. Burr-Brownrecommends that all integrated circuits be handled withappropriate precautions. Failure to observe proper handlingand installation procedures can cause damage.

ESD damage can range from subtle performance degrada-tion to complete device failure. Precision integrated circuitsmay be more susceptible to damage because very smallparametric changes could cause the device not to meet itspublished specifications.

ABSOLUTE MAXIMUM RATINGSSupply Voltage, V+ to V– .................................................................... 36VLogic Input Voltage ...................................................................... V– to V+Output Short Circuit to Ground ............................................... ContinuousOperating Temperature ................................................. –40°C to +125°CStorage Temperature ..................................................... –55°C to +125°CLead Temperature (soldering, 10s) ................................................. 300°C

PIN CONNECTIONS

Top View 14-Pin DIP/SO-14 Surface Mount

PACKAGE INFORMATION

PACKAGE DRAWINGPRODUCT PACKAGE NUMBER (1)

IVC102P 14-Pin DIP 010IVC102U SO-14 Surface Mount 235

NOTE: (1) For detailed drawing and dimension table, please see end of datasheet, or Appendix D of Burr-Brown IC Data Book.

V+

Digital Ground

S2

S1

VO

V–

NC

Analog Ground

IIN

–In

C1

C2

C3

NC

NC = No Internal Connection Connect to Analog Ground for Lowest Noise

14

13

12

11

10

9

8

1

2

3

4

5

6

7

4®

IVC102

10 100 1000

CIN (pF)

TOTAL OUTPUT NOISE vs CIN1000

100

10

1

Noi

se V

olta

ge (

µVrm

s)

rms Variationof 100 MeasurementCycles, TINT = 1ms.

CINT = 10pF

CINT = 30pF

CINT = 100pF

CINT = 300pF

CINT = 1000pF

Reset Mode, S1 Open, S2 Closed.

TYPICAL PERFORMANCE CURVESAt TA = +25°C, VS = ±15V, RL = 2kΩ, CINT = C1 + C2 + C3, 1ms integration period, unless otherwise specified.

–50 –25 0 25 50 75 100 125

Temperature (°C)

INPUT BIAS CURRENT vs TEMPERATURE100p

10p

1p

100f

10f

Inpu

t Bia

s C

urre

nt (

A)

S1, S2 Open

0 100 200 300 400 500 600 700 800 900 1000

CINT (pF)

RESET TIME vs CINT30

25

20

15

10

5

0

Res

et T

ime

(µs)

Time Required toReset from ±10Vto 0V.

0.01%

1%

10 100 1000

Input Capacitance, CIN (pF)

S1 CHARGE INJECTION vs INPUT CAPACITANCE2.0

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0

Cha

rge

Inje

ctio

n, ∆

Q (

pC)

100pF

∆VO =∆Q

100pF

S1

CIN

10 100 1000

Input Capacitance, CIN (pF)

S2 CHARGE INJECTION vs INPUT CAPACITANCE1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

Cha

rge

Inje

ctio

n, ∆

Q (

pC)

(V+) = +18V

(V+) = +15V

(V+) = +4.75V

100pF

∆VO =∆Q

100pF

CIN

S2

5®

IVC102

Charge Injectionof S2

Op Amp VOS+

IIN • RS2

0V

Integrate

(S2 Open)

T1

0V

S2

VO

T2

10µsReset

10µsReset

IIN

Photodiode

60pF

30pF

10pF

0.1µF

0.1µF

1

2

3

4

5

6

11 12 13

10 VO

14

V++15V

LogicHigh(+5V)

S1

C1

C2

C3

S2DigitalGround

AnalogGround

S2

9

–15VV–

DigitalData

SamplingA/D

Converter

See timingsignal below

APPLICATION INFORMATIONFigure 1 shows the basic circuit connections to operate theIVC102. Bypass capacitors are shown connected to thepower supply pins. Noisy power supplies should be avoidedor decoupled and carefully bypassed.

The Analog Ground terminal, pin 1, is shown internallyconnected to the non-inverting input of the op amp. Thisterminal connects to other internal circuitry and should beconnected to ground. Approximately 200µA flows out ofthis terminal.

Digital Ground, pin 13, should be at the same voltagepotential as analog ground (within 100mV). Analog andDigital grounds should be connected at some point in thesystem, usually at the power supply connections to thecircuit board. A separate Digital Ground is provided so thatnoisy logic signals can be referenced to separate circuitboard traces.

Integrator capacitors C1, C2 and C3 are shown connected inparallel for a total CINT = 100pF. The IVC102 can be usedfor a wide variety of integrating current measurements. Theinput signal connections and control timing and CINT valuewill depend on the sensor or signal type and other applica-tion details.

BASIC RESET-AND-INTEGRATE MEASUREMENT

Figure 1 shows the circuit and timing for a simple reset-and-integrate measurement. The input current is connected di-rectly to the inverting input of the IVC102, pin 3. Inputcurrent is shown flowing out of pin 3, which produces apositive-going ramp at VO. Current flowing into pin 3 wouldproduce a negative-going ramp.

A measurement cycle starts by resetting the integrator outputvoltage to 0V by closing S2 for 10µs. Integration of the inputcurrent begins when S2 opens and the input current begins tocharge CINT. VO is measured with a sampling a/d converterat the end of an integration period, just prior to the next resetperiod. The ideal result is proportional to the average inputcurrent (or total accumulated charge).

Switch S2 is again closed to reset the integrator output to 0Vbefore the next integration period.

This simple measurement arrangement is suited to manyapplications. There are, however, limitations to this basicapproach. Input current continues to flow through S2 duringthe reset period. This leaves a small voltage on CINT equalto the input current times RS2, the on-resistance of S2,approximately 1.5kΩ.

FIGURE 1. Reset-and Integrate Connections and Timing.

Figure 1b

Figure 1a

6®

IVC102

CINT

for constant IIN, at the end of TINT

VO = –IINTINTCINT

VO

IIN

IIN(t)VO =–1 ∫ dtCINT

In addition, the offset voltage of the internal op amp andcharge injection of S2 contribute to the voltage on CINT at thestart of integration.

Performance of this basic approach can be improved bysampling VO after the reset period at T1 and subtracting this

measurement from the final sample at T2. Op amp offsetvoltage, charge injection effects and I•RS2 offset voltage onS2 are removed with this two-point measurement. The effec-tive integration period is the time between the two measure-ments, T2-T1.

COMPARISON TO CONVENTIONAL TRANSIMPEDANCE AMPLIFIERS

With the conventional transimpedance amplifier circuitof Figure 2a, input current flows through the feedbackresistor, RF, to create a proportional output voltage.

VO = –IIN RFThe transimpedance gain is determined by RF. Very largevalues of RF are required to measure very small signalcurrent. Feedback resistor values exceeding 100MΩ arecommon.

The IVC102 (Figure 2b) provides a similar function,converting an input current to an output voltage. Theinput current flows through the feedback capacitor, CINT,charging it at a rate that is proportional to the inputcurrent. With a constant input current, the IVC102’soutput voltage is

VO = –IIN TINT/ CINT

after an integration time of TINT.

VO is proportional to the integration time, TINT, andinversely proportional to the feedback capacitor, CINT.The effective transimpedance gain is TINT /CINT. Ex-tremely high gain that would be impractical to achievewith a conventional transimpedance amplifier can beachieved with small integration capacitor values and/orlong integration times. For example the IVC102 withCINT = 100pF and TINT = 100ms provides an effectivetransimpedance of 1GΩ. A 10nA input current wouldproduce a 10V output after 100ms integration.

The integrating behavior of the IVC102 reduces noise byaveraging the input noise of the sensor, amplifier, andexternal sources.

Conventional Transimpedance AmplifierFigure 2a

Integrating Transimpedance AmplifierFigure 2b

RF

VO = –IIN RF

VO

IIN

CURRENT-OUTPUT SENSORS

Figure 3 shows a model for many current-output sensorssuch as photodiodes and ionization chambers. Sensor outputis a signal-dependent current with a very high source resis-tance. The output is generally loaded into a low impedance

FIGURE 2. Comparison to a Conventional Transimpedance Amplifier.

so that the terminal voltage is kept very low. Typical sensorcapacitance values range from 10pF to over 100pF. Thiscapacitance plays a key role in operation of the switched-input measurement technique (see next section).

Provides time-continuous outputvoltage proportional to IIN.

Output voltage after integration period isproportional to average IIN throughoutthe period.

7®

IVC102

60pF

30pF

10pF

0.1µF

0.1µF

1

I

PhotodiodeSensor

R C

2

3

4

5

6

11

I: Signal - Dependent CurrentR: Sensor ResistanceC: Sensor Capacitance

12 13

10 VO

14

V++15V

S1

S1

C1

C2

C3

S2

S2

9

–15VV–

DigitalData

A/DConverter

See timingsignals below

3a

3b

3c

Charge transferredfrom sensor Cto CINT.

A

A

B

B

Transfer FunctionOffset Voltage

Ramp due toinput bias current

(exaggerated).

EffectiveSignal Integration

Period, TS

VO waveform withapprox. half-scale input current.

VO waveform withzero input current.

∆QS1 Opening

0V

0V

0V

VO

S2

S1

VO

0V

+10mV

–10mV

10µsHold

10µsReset

10µsHold

10µsReset

10µsPre-Int.

Hold

∆QS2 Opening

∆QS1 Closing

Op AmpVOS

(S1 Open) (S1 Closed)

(S2 Open)

FIGURE 3. Switched-Input Measurement Technique.

Input connections and timing are shown in Figure 3.

The timing diagram, Figure 3b, shows that S1 is closed onlywhen S2 is open. During the short period that S1 is open(30µs in this timing example), any signal current producedby the sensor will charge the sensor’s source capacitance.This charge is then transferred to CINT when S1 is closed. Asa result, no charge produced by the sensor is lost and theinput signal is continuously integrated. Even fast inputpulses are accurately integrated.

SWITCHED-INPUT MEASUREMENT TECHNIQUE

While the basic reset-and-integrate measurement arrange-ment in Figure 1 is satisfactory for many applications, theswitched-input timing technique shown in Figure 3 hasimportant advantages. This method can provide continuousintegration of the input signal. Furthermore, it can hold theoutput voltage constant after integration for stable conver-sion (desirable for a/d converter without a sample/hold).

8®

IVC102

The input current, IIN, is shown as a conventional currentflowing into pin 2 in this diagram but the input current couldbe bipolar (positive or negative). Current flowing out of pin2 would produce a positive-ramping VO.

The timing sequence proceeds as follows:

Reset PeriodThe integrator is reset by closing switch S2 with S1 open. A10µs reset time is recommended to allow the op amp to slewto 0V and settle to its final value.

Pre-Integration HoldS2 is opened, holding VO constant for 10µs prior to integra-tion. This pre-integration hold period assures that S2 is fullyopen before S1 is closed so that no input signal is lost. Aminimum of 1µs is recommended to avoid switching over-lap. The 10µs hold period shown in Figure 3b also allows ana/d converter measurement to be made at point A. Thepurpose of this measurement at A is discussed in the “OffsetErrors” section.

Integration on C INTIntegration of the input current on CINT begins when S1 isclosed. An immediate step output voltage change occurs asthe charge that was stored on the input sensor capacitance istransferred to CINT. Although this period of charging CINToccurs only while S1 is closed, the charge transferred as S1is closed causes the effective integration time to be equal tothe complete conversion period—see Figure 3b.

The integration period could range from 100µs to manyminutes, depending on the input current and CINT value.While S1 is closed, IIN charges CINT, producing a negative-going ramp at the integrator output voltage, VO. The outputvoltage at the end of integration is proportional to theaverage input current throughout the complete conversioncycle, including the integration period, reset and both holdperiods.

Hold PeriodOpening S1 halts integration on CINT. Approximately 5µsafter S1 is opened, the output voltage is stable and can bemeasured (at point B). The hold period is 10µs in thisexample. CINT remains charged until a S2 is again closed, toreset for the next conversion cycle.

In this timing example, S1 is open for a total of 30µs. Duringthis time, signal current from the sensor charges the sensorsource capacitance. Care should be used to assure that thevoltage developed on the sensor does not exceed approxi-mately 200mV during this time. The IIN terminal, pin 2, isinternally clamped with diodes. If these diodes forward bias,signal current will flow to ground and will not be accuratelyintegrated.

A maximum of 333nA signal current could be accuratelyintegrated on a 50pF sensor capacitance for 30µs before200mV would be developed on the sensor.

IMAX = (50pF) (200mV) / 30µs = 333nA

OFFSET ERRORS

Figure 3c shows the effect on VO due to op amp input offsetvoltage, input bias current and switch charge injection. Itassumes zero input current from the sensor. The variousoffsets and charge injection (∆Q) jumps shown are typical ofthat seen with a 50pF source capacitance. The specified“transfer function offset voltage” is the voltage measuredduring the hold period at B. Transfer function offset voltageis dominated by the charge injection of S2 opening and opamp VOS. The opening and closing charge injections of S1are very nearly equal and opposite and are not significantcontributors.

Note that using a two-point difference measurement at Aand B can dramatically reduce offset due to op amp VOS andS2 charge injection. The remaining offset with this B-Ameasurement is due to op amp input bias current chargingCINT. This error is usually very small and is exaggerated inthe figure.

DIGITAL SWITCH INPUTS

The digital control inputs to S1 and S2 are compatible withstandard CMOS or TTL logic. Logic input pins 11 and 12are high impedance and the threshold is approximately 1.4Vrelative to Digital Ground, pin 13. A logic “low” closes theswitch.

Use care in routing these logic signals to their respectiveinput pins. Capacitive coupling of logic transitions to sensi-tive input nodes (pins 2 through 6) and to the positive powersupply (pin 14) will dramatically increase charge injectionand produce errors. Route these circuit board traces over aground plane (digital ground) and route digital ground tracesbetween logic traces and other critical traces for lowestcharge injection. See Figure 4.

5V logic levels are generally satisfactory. Lower voltagelogic levels may help reduce charge injection errors, de-pending on circuit layout. Logic high voltages greater than5.5V, or higher than the V+ supply are not recommended.

FIGURE 4. Circuit Board Layout Techniques.

•

••

•

•

•

•

•

•

•

•

•

•

•

•

Input trace guardedall the way to sensor.

Switch logic inputsguarded by digitalground.

AnalogGround

DigitalGround

Pins 7 and 8 have no internal connection but are connected toground for lowest noise pickup.

V+

Input nodesguarded byanalog ground.

V–

VO

S1

S2

14

87

1

9®

IVC102

CHOOSING CINTInternal capacitors C1, C2 and C3 are high quality metal/oxide types with low leakage and excellent dielectric char-acteristics. Temperature stability is excellent—see typicalcurve. They can be connected for CINT = 10pF, 30pF, 40pF,60pF, 70pF, 90pF or 100pF. Connect unused internal ca-pacitor pins to analog ground. Accuracy is ±20%, whichdirectly influences the gain of the transfer function.

A larger value external CINT can be connected between pins3 and 10 for slower/longer integration. Select a capacitortype with low leakage and good temperature stability.Teflon, polystyrene or polypropylene capacitors generallyprovide excellent leakage, temperature drift and voltagecoefficient characteristics. Lower cost types such as NPOceramic, mica or glass may be adequate for many applica-tions. Larger values for CINT require a longer reset time—seetypical curves.

FREQUENCY RESPONSE

Integration of the input signal for a fixed period produces adeep null (zero response) at the frequency 1/TINT and itsharmonics. An ac input current at this frequency (or itsharmonics) has zero average value and therefore producesno output. This property can be used to position responsenulls at critical frequencies. For example, a 16.67ms integra-tion period produces response nulls at 60Hz, 120Hz, 180Hz,etc., which will reject ac line frequency noise and its har-monics. Response nulls can be positioned to reduce interfer-ence from system clocks or other periodic noise.Response to all frequencies above f = 1/TINT falls at –20dB/decade. The effective corner frequency of this single-poleresponse is approximately 1/2.8TINT.

For the simple reset-and-integrate measurement technique,TINT is equal to the to the time that S2 is open. The switched-input technique, however, effectively integrates the inputsignal throughout the full measurement cycle, including thereset period and both hold periods. Using the timing shownin Figure 3, the effective integration time is 1/Ts, where Tsis the repetition rate of the sampling.

INPUT IMPEDANCE

The input impedance of a perfect transimpedance circuit iszero ohms. The input voltage ideally would be zero for anyinput current. The actual input voltage when directly drivingthe integrator input (pin 3) is proportional to the output slewrate of the integrator. A 1V/µs slew rate produces approxi-mately 100mV at pin 3. The input of the integrator can bemodeled as a resistance:

RIN = 10–7/CINT

with RIN in Ω and CINT in Farads.

Using the internal CINT = C1 + C2 + C3 = 100pF

RIN = 10–7/100pF = 1kΩ

(2)

(3)

INPUT BIAS CURRENT ERRORS

Careful circuit board layout and assembly techniques arerequired to achieve the very low input bias current capabilityof the IVC102. The critical input connections are at groundpotential, so analog ground should be used as a circuit boardguard trace surrounding all critical nodes. These includepins 2, 3, 4, 5 and 6. See Figure 4.

Input bias current increases with temperature—see typicalperformance curve Input Bias Current vs Temperature.

HOLD MODE DROOP

Hold-mode droop is a slow change in output voltage prima-rily due to op amp input bias current. Droop is specifiedusing the internal CINT = 100pF and is based on a –100fAtypical input bias current. Current flows out of the invertinginput of the internal op amp.

With CINT = 100pF, the droop rate is typically only1nV/µs—slow enough that it rarely contributes significanterror at moderate temperatures.

Since the input bias current increases with temperature, thedroop rate will also increase with temperature. The drooprate will approximately double for each 10°C increase injunction temperature—see typical curves.

Droop rate is inversely proportional to CINT. If an externalintegrator capacitor is used, a low leakage capacitor shouldbe selected to preserve the low droop performance of theIVC102.

INPUT CURRENT RANGE

Extremely low input currents can be measured by integrat-ing for long periods and/or using a small value for CINT.Input bias current of the internal op amp is the primarysource of error.

Larger input currents can be measured by increasing thevalue of CINT and/or using a shorter integration time. Inputcurrents greater than 200µA should not be applied to the pin2 input, however. The approximately 1.5kΩ series resistanceof S1 will create an input voltage at pin 2 that will begin toforward-bias internal protection clamp diodes. Any currentthat flows through these protection diodes will not be accu-rately integrated. See “Input Impedance” section for moreinformation on input current-induced voltage.

Input current greater than 200µA can, however, be con-nected directly to pin 3, using the simple reset-integratetechnique shown in Figure 1. Current applied at this inputcan be externally switched to avoid excessive I•R voltageacross S2 during reset. Inputs up to 5mA at pin 3 can beaccurately integrated if CINT is made large enough to limitslew rate to less than 1V/µs. A 5mA input current wouldrequire CINT = 5nF to produce a 1V/µs slew rate. The inputcurrent appears as load current to the internal op amp,reducing its ability to drive an external load.

Droop Rate = –100fACINT

Teflon E. I. Du Pont de Nemours & Co.

10®

IVC102

The input resistance seen at pin 2 includes an additional1.5kΩ, the on-resistance of S1. The total input resistance isthe sum of the switch resistance and RIN, or 2.5kΩ in thisexample.

Slew rate limit of the internal op amp is approximately3V/µs. For most applications, the slew rate of VOUT shouldbe limited to 1V/µs or less. The rate of change is propor-tional to IIN and inversely proportional to CINT:

This can be important in some applications since the slew-induced input voltage is applied to the sensor or signalsource. The slew-induced input voltage can be reduced byincreasing CINT, which reduces the output slew rate.

NONLINEARITY

Careful nonlinearity measurements of the IVC102 yieldtypical results of approximately ±0.005% using the internalinput capacitors (CINT = 100pF). Nonlinearity will be de-graded by using an external integrator capacitor with poorvoltage coefficient. Performance with the internal capacitorsis typically equal or better than the sensors it is used tomeasure. Actual application circuits with sensors such as aphotodiode may have other sources of nonlinearity.

1/10TINT 1/TINT 10/TINT

● ●●

–20dB/decadeslope

Frequency

0

–10

–20

–30

–40

–50

Fre

quen

cy R

espo

nse

(dB

)

Corner atf = 0.32/TINT

–3dB atf = 0.44/TINT

FIGURE 5. Frequency Response of Integrating Converter.

Slew Rate = IINCINT

PACKAGE OPTION ADDENDUM

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Addendum-Page 1

PACKAGING INFORMATION

Orderable Device Status(1)

Package Type PackageDrawing

Pins PackageQty

Eco Plan(2)

Lead finish/Ball material

(6)

MSL Peak Temp(3)

Op Temp (°C) Device Marking(4/5)

Samples

IVC102U ACTIVE SOIC D 14 50 RoHS & Green NIPDAU Level-3-260C-168 HR -40 to 125 IVC102U

IVC102U/2K5 ACTIVE SOIC D 14 2500 RoHS & Green NIPDAU Level-3-260C-168 HR -40 to 125 IVC102U

(1) The marketing status values are defined as follows:ACTIVE: Product device recommended for new designs.LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.PREVIEW: Device has been announced but is not in production. Samples may or may not be available.OBSOLETE: TI has discontinued the production of the device.

(2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substancedo not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI mayreference these types of products as "Pb-Free".RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of

PACKAGE OPTION ADDENDUM

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Addendum-Page 2

TAPE AND REEL INFORMATION

*All dimensions are nominal

Device PackageType

PackageDrawing

Pins SPQ ReelDiameter

(mm)

ReelWidth

W1 (mm)

A0(mm)

B0(mm)

K0(mm)

P1(mm)

W(mm)

Pin1Quadrant

IVC102U/2K5 SOIC D 14 2500 330.0 16.4 6.5 9.0 2.1 8.0 16.0 Q1

PACKAGE MATERIALS INFORMATION

www.ti.com 30-Dec-2020

Pack Materials-Page 1

*All dimensions are nominal

Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)

IVC102U/2K5 SOIC D 14 2500 853.0 449.0 35.0

PACKAGE MATERIALS INFORMATION

www.ti.com 30-Dec-2020

Pack Materials-Page 2

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