LOG114SBOS301A − MAY 2004 − REVISED MARCH 2007Single-Supply, High-Speed, PrecisionLOGARITHMIC AMPLIFIERFEATURESDADVANTAGES:− Tiny for High Density Systems− Precision on One Supply− Fast Over Eight Decades− Fully-Tested FunctionTWO SCALING AMPLIFIERSWIDE INPUT DYNAMIC RANGE: Eight Decades, 100pA to 10mA2.5V REFERENCESTABLE OVER TEMPERATURELOW QUIESCENT CURRENT: 10mADUAL OR SINGLE SUPPLY: +5V, +5VPACKAGE: Small QFN-16 (4mm x 4mm)SPECIFIED TEMPERATURE RANGE: −5°C to +75°CDESCRIPTIONThe LOG114 is specifically designed for measuringlow-level and wide dynamic range currents incommunications, lasers, medical, and industrialsystems. The device computes the logarithm or log-ratioof an input current or voltage relative to a referencecurrent or voltage (logarithmic transimpedanceamplifier).High precision is ensured over a wide dynamic range ofinput signals on either bipolar (±5V) or single (+5V)supply. Special temperature drift compensation circuitryis included on-chip. In log-ratio applications, the signalcurrent may be from a high impedance source such asa photodiode or resistor in series with a low impedancevoltage source. The reference current is provided by aresistor in series with a precision internal voltagereference, photo diode, or active current source.The output signal at VLOGOUT has a scale factor of 0.375Vout per decade of input current, which limits the outputso that it fits within a 5V or 10V range. The output can bescaled and offset with one of the available additionalamplifiers, so it matches a wide variety of ADC inputranges. Stable dc performance allows accuratemeasurement of low-level signals over a widetemperature range. The LOG114 is specified over a−5°C to +75°C temperature range and can operate from−40°C to +85°C.R5R6DDDDDDDDAPPLICATIONSDONET ERBIUM-DOPED FIBER OPTICDDDLOG, LOG-RATIO FUNCTIONDANALOG SIGNAL COMPRESSION IN FRONTDAMPLIFIER (EDFA)LASER OPTICAL DENSITY MEASUREMENTPHOTODIODE SIGNAL COMPRESSION AMPOF ANALOG-TO-DIGITAL (ADC) CONVERTERABSORBANCE MEASUREMENTVLOGOUT9(2)Q1I14VCMIN5I1andI2arecurrentinputsfromaphotodiodeorothercurrentsourceQ2I23RREF16VREF2.5VREFA2200ΩR3(1)A3(4)A1200ΩR(1)110+IN411−IN4LOG1141250ΩR2A4VO4(3)12131250ΩR4A5+IN515VO5IREF1VREFGND8V+6V−7Com14−IN5NOTES:(1)ThermallydependentR1andR3providetemperaturecompensation.(2)VLOGOUT=0.375×log(I1/I2).(3)VO4=0.375×K×log(I1/I2)K=1+R6/R5.(4)DifferentialAmplifier(A3)Gain=6.25Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of TexasInstrumentssemiconductor products and disclaimers thereto appears at the end of this data sheet.All trademarks are the property of their respective owners.PRODUCTION DATA information is current as of publication date. Productsconform to specifications per the terms of Texas Instruments standard warranty.Production processing does not necessarily include testing of all parameters.Copyright 2004−2007, Texas Instruments Incorporatedwww.ti.comLOG114www.ti.comSBOS301A − MAY 2004 − REVISED MARCH 2007ABSOLUTE MAXIMUM RATINGS(1)Supply Voltage, V+ to V−. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12VSignal Input Terminals, Voltage(2) . . . . . (V−) −0.5V to (V+) + 0.5VCurrent(2) . . . . . . . . . . . . . . . . . . . . ±10mAOutput Short-Circuit(3) Continuous. . . . . . . . . . . . . . . . . . . . . . . . . . Operating Temperature. . . . . . . . . . . . . . . . . . . . . . −40°C to +85°CStorage Temperature. . . . . . . . . . . . . . . . . . . . . . . −55°C to +125°CJunction Temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +150°CESD Rating (Human Body Model). . . . . . . . . . . . . . . . . . . . 2000V(1)Stresses above these ratings may cause permanent damage.Exposure to absolute maximum conditions for extended periodsmay degrade device reliability. These are stress ratings only, andfunctional operation of the device at these or any other conditionsbeyond those specified is not implied.(2)Input terminals are diode-clamped to the power-supply rails.Input signals that can swing more than 0.5V beyond the supplyrails should be current-limited to 10mA or less.(3)Short-circuit to ground.This integrated circuit can be damaged by ESD. TexasInstruments recommends that all integrated circuits behandled with appropriate precautions. Failure to observeproper handling and installation procedures can cause damage.ESD damage can range from subtle performance degradation tocomplete device failure. Precision integrated circuits may be moresusceptible to damage because very small parametric changes couldcause the device not to meet its published specifications.PRECISION CURRENT MEASUREMENTPRODUCTSFEATURESLogarithmic Transimpedance Amplifier, 5V, Eight DecadesLogarithmic Transimpedance, 36V, 7.5 DecadesResistor-Feedback Transimpedance, 5V, 5.5 DecadesSwitched Integrator Transimpedance, Six DecadesDirect Digital Converter, Six DecadesPRODUCTLOG114LOG112OPA380,OPA381IVC102DDC112ORDERING INFORMATION(1)PRODUCTLOG114PACKAGE-LEADQFN-16PACKAGE DESIGNATORRGVPACKAGE MARKINGLOG114(1)For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI web siteat www.ti.com.PIN CONFIGURATIONTop ViewVREF−IN5+IN5VO5QFN-1616VREFGNDNCI2I1123415141312VO4Exposedthermaldiepadonunderside(MustbeconnectedtoV−)11−IN410+IN49VLOGOUT5VCMIN6V−7Com8V+QFN−16(4mmx4mm)NC=NoConnection2LOG114www.ti.comSBOS301A − MAY 2004 − REVISED MARCH 2007ELECTRICAL CHARACTERISTICS: VS = +5V Boldface limits apply over the specified temperature range, TA = −5°C to +75°C.All specifications at TA = +25°C, RVLOGOUT = 10kΩ, VCM = GND, unless otherwise noted.LOG114PARAMETERCORE LOG FUNCTIONLOG CONFORMITY ERROR(1)Initial 1nA to 100µA (5 decades) 100pA to 3.5mA (7.5 decades) 1mA to 10mAOver Temperature1nA to 100µA (5 decades)100pA to 3.5mA (7.5 decades)1mA to 10mATRANSFER FUNCTION (GAIN)(2)Initial Scaling FactorScaling Factor ErrorOver TemperatureINPUT, A1 and A2Offset Voltagevs Temperaturevs Power SupplyInput Bias Currentvs TemperatureInput Common-Mode Voltage RangeVoltage NoiseCurrent NoiseOUTPUT, A3 (VLOGOUT)Output Offset, VOSO, InitialOver TemperatureFull-Scale Output (FSO)(3)Gain Bandwidth ProductShort-Circuit CurrentCapacitive LoadOP AMP, A4 and A5Input Offset Voltagevs Temperaturevs Supplyvs Common-Mode VoltageInput Bias CurrentInput Offset CurrentInput Voltage RangeInput Noise f = 0.1Hz to 10Hzf = 1kHzCurrent NoiseOpen-Loop Voltage GainGain Bandwidth ProductSlew RateSettling Time 0.01%Rated OutputShort-Circuit CurrentISCinAOLGBWSRtSG = −1, 3V Step, CL = 100pF(V−) + 0.5+4/−10VOSdV/dTPSRRCMRRIBIOS(V−)21321001551.5(V+) − 0.5TMIN to TMAXVS = ±4.5V to ±5.5V±250±23074−1±0.05(V+) − 2250±1000µVµV/°CµV/VdBµAµAVµVPPnV/√HzpA/√HzdBMHzV/µsµsVmAGBWISCIIN = 1µAVOSOTMIN to TMAX(V−) + 0.650±18100±11±15±50±65(V+) − 0.6mVmVVMHzmApFVCMeninf = 0.1Hz to 10kHzf = 1kHzf = 1kHzVOSdV/dTPSRRIBTMIN to TMAXTMIN to TMAXVS = ±2.25V to ±5.5V±1+1575±5Doubles every 10°C(V−)+1.5 to(V+)−1.53304VµVrmsnV/√HzfA/√Hz400±4mVµV/°CµV/VpA100pA to 10mA1nA to 100µATMIN to TMAX+15°C to +50°C0.3750.40.0351.50.7±2.50.21±3.5±3V/decade%dB%%0.10.0090.90.08See Typical Characteristics0.10.5See Typical Characteristics0.4%%%0.20.017%dB%dBCONDITIONSIIN/VOUT EquationMINTYPVO = (0.375V) Log (I1/I2)MAXUNITSV3LOG114www.ti.comSBOS301A − MAY 2004 − REVISED MARCH 2007ELECTRICAL CHARACTERISTICS: VS = +5V (continued)Boldface limits apply over the specified temperature range, TA = −5°C to +75°C.All specifications at TA = +25°C, RVLOGOUT = 10kΩ, VCM = GND, unless otherwise noted.LOG114PARAMETERTOTAL ERROR(4, 5)FREQUENCY RESPONSE, Core Log(6)BW, 3dB I1 or I2 =1nA10nA100nA1µA10µA to 1mA (ratio 1:100)1mA to 3.5mA (ratio 1:3.5)3.5mA to 10mA (ratio 1:2.9)Step ResponseIncreasing (I1 or I2)8nA to 240nA (ratio 1:30)10nA to 100nA (ratio 1:10)10nA to 1µA (ratio 1:100)10nA to 10µA (ratio 1:1k)10nA to 1mA (ratio 1:100k)1mA to 10mA (ratio 1:10)Decreasing (I1 or I2)8nA to 240nA (ratio 1:30)10nA to 100nA (ratio 1:10)10nA to 1µA (ratio 1:100)10nA to 10µA (ratio 1:1k)10nA to 1mA (ratio 1:100k)1mA to 10mA (ratio 1:10)VOLTAGE REFERENCEBandgap VoltageError, Initialvs Temperaturevs Supplyvs LoadShort-Circuit CurrentPOWER SUPPLYDual Supply Operating RangeQuiescent CurrentTEMPERATURE RANGESpecification, TMIN to TMAXOperatingStorageThermal Resistance, qJA −5−40−5562+75+85+125°C°C°C°C/WVSIQIO = 0±2.4±10±5.5±15VmAVS = ±4.5V to ±5.5VIO = ±2mA2.5±0.15±25±30±200±10±1V%ppm/°Cppm/Vppm/mAmAIREF = 1µA120.250.050.031µsµsµsµsµsµs0.71.50.150.070.061µsµsµsµsµsµsIREF = 1µAIAC = 10% of IDC value, IREF = 1µA5121202.3> 5> 5> 5kHzkHzkHzMHzMHzMHzMHzCONDITIONSMINTYPSee Typical CharacteristicsMAXUNITS(1)Log conformity error is peak deviation from the best-fit straight line of VO vs Log (I1/I2) curve expressed as a percent of peak-to-peak full-scale output. Scale factor,K, equals 0.375V output per decade of input current.(2)Scale factor of core log function is trimmed to 0.375V output per decade change of input current.(3)Specified by design.(4)Worst-case total error for any ratio of I1/I2, as the largest of the two errors, when I, and I2 are considered separately.(5)Total error includes offset voltage, bias current, gain, and log conformity.(6)Small signal bandwidth (3dB) and transient response are a function of the level of input current. Smaller input current amplitude results in lower bandwidth.4LOG114www.ti.comSBOS301A − MAY 2004 − REVISED MARCH 2007ELECTRICAL CHARACTERISTICS: VS = +5V Boldface limits apply over the specified temperature range, TA = −5°C to +75°C.All specifications at TA = +25°C, RVLOGOUT = 10kΩ, VCM = +2.5V, unless otherwise noted.LOG114PARAMETERCORE LOG FUNCTIONLOG CONFORMITY ERROR(1)Initial 1nA to 100µA (5 decades) 100pA to 3.5mA (7.5 decades) 1mA to 10mAOver Temperature1nA to 100µA (5 decades)100pA to 3.5mA (7.5 decades)1mA to 10mATRANSFER FUNCTION (GAIN)(2)Initial Scaling FactorScaling Factor ErrorOver TemperatureINPUT, A1 and A2Offset Voltagevs Temperaturevs Power SupplyInput Bias Currentvs TemperatureInput Common-Mode Voltage RangeVoltage NoiseCurrent NoiseOUTPUT, A3 (VLOGOUT)Output Offset, VOSO, InitialOver TemperatureFull Scale Output (FSO)(3)Gain Bandwidth ProductShort-Circuit CurrentCapacitive LoadOP AMP, A4 and A5Input Offset Voltagevs Temperaturevs Supplyvs Common-Mode VoltageInput Bias CurrentInput Offset CurrentInput Voltage RangeInput Noise f = 0.1Hz to 10Hzf = 1kHzCurrent NoiseOpen-Loop Voltage GainGain Bandwidth ProductSlew RateSettling Time 0.01%Rated OutputShort-Circuit CurrentISCinAOLGBWSRtSG = −1, 3V Step, CL = 100pF(V−) + 0.5+4/−10VOSdV/dTPSRRCMRRIBIOS(V−)12821001551.5(V+) − 0.5TMIN to TMAXVS = +4.8V to +5.5V±250±23070−1±0.05(V+) − 1.5±4000µVµV/°CµV/VdBµAµAVµVPPnV/√HzpA/√HzdBMHzV/µsµsVmAGBWISCVOSOTMIN to TMAXVS = +5VIIN = 1µA(V−) + 0.650±18100±14±18±65±80(V+) − 0.6mVmVVMHzmApFVCMeninf = 0.1Hz to 10kHzf = 1kHzf = 1kHzVOSdV/dTPSRRIBTMIN to TMAXTMIN to TMAXVS = +4.5V to +5.5V±1+30300±5Doubles every 10°C(V−)+1.5 to(V+)−1.53304VµVrmsnV/√HzfA/√Hz±7mVµV/°CµV/VpA10nA to 100µA1nA to 100µATMIN to TMAX+15°C to +50°C0.3750.40.0.350.0350.7±2.50.21±3.5±3V/decade%dB%%0.10.0090.90.08See Typical Characteristics0.10.5See Typical Characteristics0.4%%0.250.022%dB%dBCONDITIONSIIN/VOUT EquationMINTYPMAXUNITSVVO = (0.375V) Log (I1/I2) + VCM5LOG114www.ti.comSBOS301A − MAY 2004 − REVISED MARCH 2007ELECTRICAL CHARACTERISTICS: VS = +5V (continued)Boldface limits apply over the specified temperature range, TA = −5°C to +75°C.All specifications at TA = +25°C, RVLOGOUT = 10kΩ, VCM = +2.5V, unless otherwise noted.LOG114PARAMETERTOTAL ERROR(4, 5)FREQUENCY RESPONSE, Core Log(6)BW, 3dB I1 or I2 =1nA10nA100nA1µA10µA to 1mA (ratio 1:100)1mA to 3.5mA (ratio 1:3.5)3.5mA to 10mA (ratio 1:2.9)Step ResponseIncreasing (I1 or I2)8nA to 240nA (ratio 1:30)10nA to 100nA (ratio 1:10)10nA to 1µA (ratio 1:100)10nA to 10µA (ratio 1:1k)10nA to 1mA (ratio 1:100k)1mA to 10mA (ratio 1:10)Decreasing (I1 or I2)8nA to 240nA (ratio 1:30)10nA to 100nA (ratio 1:10)10nA to 1µA (ratio 1:100)10nA to 10µA (ratio 1:1k)10nA to 1mA (ratio 1:100k)1mA to 10mA (ratio 1:10)VOLTAGE REFERENCEBandgap VoltageError, Initialvs Temperaturevs Supplyvs LoadShort-Circuit CurrentPOWER SUPPLYSingle Supply Operating RangeQuiescent CurrentTEMPERATURE RANGESpecification, TMIN to TMAXOperatingStorageThermal Resistance, qJA −5−40−5562+75+85+125°C°C°C°C/WVSIQ IO = 04.8±1011±15VmAVS = +4.8V to +11VIO = ±2mA2.5±0.15±25±30±200±10±1V%ppm/°Cppm/Vppm/mAmAIREF = 1µA120.250.050.031µsµsµsµsµsµs0.71.50.150.070.061µsµsµsµsµsµsIREF = 1µAIAC = 10% of IDC value, IREF = 1µA5121202.3> 5> 5> 5kHzkHzkHzMHzMHzMHzMHzCONDITIONSMINTYPSee Typical CharacteristicsMAXUNITS(1)Log conformity error is peak deviation from the best-fit straight line of VO vs Log (I1/I2) curve expressed as a percent of peak-to-peak full-scale output. Scale factor,K, equals 0.375V output per decade of input current.(2)Scale factor of core log function is trimmed to 0.375V output per decade change of input current.(3)Specified by design.(4)Worst-case total error for any ratio of I1/I2, as the largest of the two errors, when I, and I2 are considered separately.(5)Total error includes offset voltage, bias current, gain, and log conformity.(6)Small signal bandwidth (3dB) and transient response are a function of the level of input current. Smaller input current amplitude results in lower bandwidth.6LOG114www.ti.comSBOS301A − MAY 2004 − REVISED MARCH 2007TYPICAL CHARACTERISTICS: VS = +5V All specifications at TA = +25°C, RVLOGOUT = 10kΩ, VCM = GND, unless otherwise noted.2.0NormalizedOutputVoltage(V)1.51.00.50−0.5−1.0−1.5−2.010−410−3NORMALIZEDTRANSFERFUNCTION0.40NormalizedOutputVoltage(V)0.350.300.250.200.150.100.0501ONECYCLEOFNORMALIZEDTRANSFERFUNCTION10−210−1110110210310410CurrentRatio(I1/I2)CurrentRatio(I1/I2)4030GainError(%)20SCALINGFACTORERROR(I2=reference100pAto10mA)2.52.01.51.0VLOGOUT(V)VLOGOUTvsI1INPUT(I2=1µA)100−10−20+70_C0_C+25_C0.50−0.5−1.0−1.5−2.0−2.5−10_C+80_C+90_C10nA100nA1µA10µA100µA1mA10mA100pA1nA100pA1nA10nA100nA1µA10µA100µA1mA10mAInputCurrent(I1)InputCurrent(I1)2.01.51.0VLOGOUT(V)VLOGOUTvsI2INPUT(I1=1µA)432VLOGOUT(V)10−1−2−31µAVLOGOUTvsIREF100pA1nA10nA100nA0.50−0.5−1.0−1.5−2.0−2.5100pA1nA10nA100nA1µA10µA100µA1mA10mA10µA1mA100µA10mA10nA100nA1µAIREF(I2)10µA100µA1mA10mA−4100pA1nAInputCurrent(I1)7LOG114www.ti.comSBOS301A − MAY 2004 − REVISED MARCH 2007TYPICAL CHARACTERISTICS: VS = +5V (continued) All specifications at TA = +25°C, RVLOGOUT = 10kΩ, VCM = GND, unless otherwise noted.1008060TotalError(mV)40200−20−40−60−80−100AVERAGETOTALERRORAT+80_C10080I1=1mATotalError(mV)6040200−20−40−60I1=100nA400µAI2I1=1µA600µA800µA1mA−80−100100µAAVERAGETOTALERRORAT+25_CI1=1mAI1=100µAI1=10µAI=100µA1I1=10µAI1=10nAI1=1nA200µAI1=1µAI1=1nA,10nA,100nA800µA1mA100µA200µA400µAI2600µA1008060TotalError(mV)40200−20−40−60−80−100100µAAVERAGETOTALERRORAT−10_C1.41.2I1=1mALinearity(%)I1=1nA1.00.8LOGCONFORMITYvsTEMPERATURE7.5Decade7Decade0.66Decade0.45Decade4DecadeI1=10nAI1=100µAI1=10µAI=100nA1I1=1µA0.20200µA400µAI2600µA800µA1mA−100102030405060708090Temperature(_C)0.094DECADELOGCONFORMITYvsIREF0.400.35+90_CLinearity(%)0.300.250.200.150.10+25_C+70_C10nA100nA1µAIREF(I1)10µA100µA1mA10mA0.050_C5DECADELOGCONFORMITYvsIREF0.08Linearity(%)+90_C0.07+80_C−10_C0.06+80_C+70_C0.050.04100pA1nA−10_C,0_C,+25_C0100pA1nA10nA100nA1µAIREF(I1)10µA100µA1mA10mA8LOG114www.ti.comSBOS301A − MAY 2004 − REVISED MARCH 2007TYPICAL CHARACTERISTICS: VS = +5V (continued)All specifications at TA = +25°C, RVLOGOUT = 10kΩ, VCM = GND, unless otherwise noted. For ac measurements, small signal means up to approximately 10% of dclevel.0.456DECADELOGCONFORMITYvsIREF1.61.58DECADELOGCONFORMITY(100pAto3.5mA)0.40+90_CLinearity(%)0.35+80_C+70_CLinearity(%)1.41.31.21.1+90_C0.30+80_C0_C+70_C−10_C+25_C0.25−10_C,0_C,+25_C0.20100pA1nA10nA100nA1µAIREF(I1)10µA100µA1mA10mA1.00.9100pA1nA10nA100nA1µA10µA100µA1mA10mAInputCurrent(I1orI2)2010NormalizedVLOGOUT(%)0−10−20SMALL−SIGNALVLOGOUT10mANormalizedLOGOutput(dB)1µA1mA100nA10nA0−5−10−15−20−25−30−35−40−45−501001kSMALL−SIGNALACRESPONSEI1(10%sinemodulation)10µA100µA1nA10nA1µA1mA100nA100µA−30−40101001k10k100k1M10M100MFrequency(Hz)10µA10k100k1M10M100MFrequency(Hz)0−5NormalizedLOGOutput(dB)−10−15−20−25−30−35−40−45−501001kSMALL−SIGNALACRESPONSEI2(10%sinemodulation)160140100µA120100Gain(dB)A3GAINANDPHASEvsFREQUENCY22510µA1801nA10nA1µA1mA6040200−20−40GainPhase90100nA4510k100k1M10M100M1001k10k100k1M10M040MFrequency(Hz)Frequency(Hz)Phase(_)801359LOG114www.ti.comSBOS301A − MAY 2004 − REVISED MARCH 2007TYPICAL CHARACTERISTICS: VS = +5V (continued)All specifications at TA = +25°C, RVLOGOUT = 10kΩ, VCM = GND, unless otherwise noted.140120100Gain(dB)806040200−201A4andA5GAINANDPHASEvsFREQUENCY18030A4andA5NONINVERTINGCLOSED−LOOPRESPONSE135Phase(_)GainPhase90NormalizedOutput(dB)G=1−3G=10−6−9−12−151k10k100k1M10M100MFrequency(Hz)45101001k10k100k1M010M18MFrequency(Hz)3020100Gain(dB)−10−20−30−40−50−60−70−801kA4andA5INVERTINGCLOSED−LOOPRESPONSE100−10Gain(dB)A4andA5CAPACITIVELOADRESPONSEG=+1G=−10G=−1C=100pF−20−30−40−50C<10pF10k100k1M10M60M1k10k100k1M10M50MFrequency(Hz)Frequency(Hz)10LOG114www.ti.comSBOS301A − MAY 2004 − REVISED MARCH 2007APPLICATIONS INFORMATIONOVERVIEWThe LOG114 is a precision logarithmic amplifier that iscapable of measuring currents over a dynamic range ofeight decades. It computes the logarithm, or log ratio,of an input current relative to a reference current ac-cording to equation (1).VLOGOUT+0.375 log10Either I1 or I2 can be held constant to serve as the refer-ence current, with the other input being used for the in-put signal. The value of the reference current is selectedsuch that the output at VLOGOUT (pin 9) is zero when thereference current and input current are equal. An on-chip 2.5V reference is provided for use in generating thereference current.Two additional amplifiers, A4 and A5, are included in theLOG114 for use in scaling, offsetting, filtering, thresholddetection, or other functions.(1)The output at VLOGOUT can be digitized directly, or scaledfor an ADC input using an uncommitted or external opamp.2ǒIIǓ1BASIC CONNECTIONSFigure 1 and Figure 2 show the LOG114 in typical dualand single-supply configurations, respectively. To re-duce the influence of lead inductance of power-supplylines, it is recommended that each supply be bypassedwith a 10µF tantalum capacitor in parallel with a 1000pFceramic capacitor as shown in Figure 1 and Figure 2.Connecting these capacitors as close to the LOG114V+ supply pin to ground as possible improves supply−related noise rejection.An offsetting voltage (VCom) can be connected to theCom pin to raise the voltage at VLOGOUT. When anoffsetting voltage is used, the transfer functionbecomes:VLOGOUT+0.375 log10ǒIIǓ)V12Com(2)R7100kΩR856.2kΩR5100kΩ9IREF1µF4I15VCMINA1Q1VLOGOUT(1)1011R666.5kΩ+IN4−IN4LOG114R1R2A4VO4(2)12RREF2.5MΩInputSignal100pAto10mAQ23I2A2A3R3R4+IN5VO513A51516VREF2.5VREFVREFGND1V+81000pF10µF++5V−5VV−61000pF10µF+Com7−IN514NOTE:(1)VLOGOUT=0.375×log(I1/I2)(2)VO4=−0.249×log(I1/I2)+1.5VFigure 1. Dual Supply Configuration Example for Best Accuracy Over Eight Decades.11LOG114www.ti.comSBOS301A − MAY 2004 − REVISED MARCH 2007R5100kΩR7100kΩR666.5kΩR8316kΩ9I1IµA4RREF1.62MΩ5I1VCMIN(1)A1A4Q1VLOGOUT(2)10+IN411−IN4LOG114REF3040orREF32404.096VReferenceR1R2VO4(3)12InputcurrentfromphotodiodeorcurrentsourcePhotodiode(4)Q2I23I2A2A3+IN513R3R4A5VO515+2.5V16VREF2.5VREFVREFGND1V81000pF+5V+V−Com610µFVCom=+2.5V7−IN51NOTE:(1)(2)(3)(4)Insingle−supplyconfiguration,VCMINmustbeconnectedto≥1V.VLOGOUT=0.375×log(I1/I2)+2.5V.VO4=−0.249×log(I1/I2)+1.5V.ThecathodeofthephotodiodeisreturnedtoVREFresultinginzerobiasacrossit.ThecathodecouldbereturnedtoavoltagemorepositivethanVCMINtocreateareversebiasforreducingphotodiodecapacitance,whichincreasesspeed.Figure 2. Single-Supply Configuration Example for Measurement Over Eight Decades.12LOG114www.ti.comSBOS301A − MAY 2004 − REVISED MARCH 2007DESIGN EXAMPLE FOR DUAL-SUPPLYCONFIGURATIONGiven these conditions:4.The A4 amplifier scales and offsets the VLOGOUTsignal for use by the ADC using the equation:VO4+*SFACTOR ǒVLOGOUTǓ)VOFFSET(5)digital converter (ADC) with +5V supply and+2.5V reference voltage, so VO4 swings from+0.5V to +2.5V.1.Due to LOG114 symmetry, you can choose eitherI1 or I2 as the signal input pin. Choosing I1 as thereference makes the resistor network around A4simpler. (Note: Current must flow into pins 3 (I1) andpin 4 (I2).)2.Select the magnitude of the reference current.Since the signal (I2) spans eight decades, set I1 to1µA − four decades above the minimum I2 value.(Note that it does not have to be placed in themiddle. If I2 spanned seven decades, I1 could be setthree decades above the minimum and fourdecades below the maximum I2 value.) Thisconfiguration results in more swing amplitude in thenegative direction, which provides more sensitivity(∆VO4 per ∆I2) when the current signal decreases.3.Using Equation (1) calculate the expected range oflog outputs at VLOGOUT:ForI2+10mA:VLOGOUTDV+ = 5V and V− = −5VD100pA ≤ Input signalDThe stage following the LOG114 is an analog-to-The A4 amplifier is specified with a rated output swingcapability from (V−) +0.5V to (V+) − 0.5V.Therefore, choose the final A4 output:0V ≤ VO4 ≤ +2.5VThis output results in a 2.5V range for the 3V VLOGOUTrange, or 2.5V/3V scaling factor.5.When I2 = 10mA, VLOGOUT = −1.5V. Using theequation in step 5:VO4+*SFACTOR ǒVLOGOUTǓ)VOFFSET0V+*2.5Vń3V(*1.5V))VOFFSETTherefore, VOFFSET = 0VThe A4 amplifier configuration for VO4 = −2.5/3(VLOGOUT)+ 0V is seen in Figure 3.The overall transer function is:VO4+*0.249 log(6)ǒIIǓ)1.5V12(7)InternalA4OutputAmplifierR5100kΩVLOGOUT+5VVO4=−2/3(VLOGOUT)10mA100pAR682.5kΩI1+0.375 logI2ǒǓǒǓI1I2+)1.5V+0.375 log1mAǒ10mAǓ+*1.5VA4ForI2+100pA:VLOGOUT+0.375 log1mA+0.375 log100pA(3)Therefore, the expected voltage range at the outputof amplifier A3 is:*1.5VvVLOGOUTv)1.5V(4)ǒǓVREF+2.5V−5VR7100kΩR837.4kΩI2VO40V+2.5VA4amplifierusedtoscaleandoffsetVLOGOUTfor0Vto2.5Voutput.Figure 3. Operational Amplifier Configuration forScaling the Output Going to ADC Stage.13LOG114www.ti.comSBOS301A − MAY 2004 − REVISED MARCH 2007DESIGN EXAMPLE FOR SINGLE-SUPPLYCONFIGURATIONGiven these conditions:DDDDV+ = 5VV− = GND100pA ≤ Input signal ≤ 10mAThe stage following the LOG114 is an analog todigital converter (ADC) with +5V supply and+2.5V reference voltageThis result would be fine in a dual−supply system(V+ = +5V, V− = −5V) where the output can swingbelow ground, but does not work in a single supply+5V system. Therefore, an offset voltage must beadded to the system.4.Select an offset voltage, VCom to use for centeringthe output between (V−) + 0.6V and (V+) − 0.6V,which is the full-scale output capability of the A3amplifier. Choosing VCom = 2.5V, and recalculatingthe expected voltage output range for VLOGOUT usingEquation (2), results in:)1VvVLOGOUTv)4V(10)1.Choose either I1 or I2 as the signal input pin. For thisexample, I2 is used. Choosing I1 as the referencecurrent makes the resistor network around A4simpler. (Note: Current only flows into the I1 and I2pins.)2.Select the magnitude of the reference current.Since the signal (I2) spans eight decades, set I1 to1µA − four decades above the minimum I2 value,and four decades below the maximum I2 value.(Note that it does not have to be placed in themiddle. If I2 spanned seven decades, I1 could be setthree decades above the minimum and fourdecades below the maximum I2 value.) Thisconfiguration results in more swing amplitude in thenegative direction, which provides more sensitivity(∆VO4 per ∆I2) when the current signal decreases.3.Using Equation (1) calculate the expected range oflog outputs at VLOGOUT:ForI2+10mA:VLOGOUT5.The A4 amplifier scales and offsets the VLOGOUTsignal for use by the ADC using the equation:VO4+*SFACTOR ǒVLOGOUTǓ)VOFFSET(11)The A4 amplifier is specified with a rated output swingcapability from (V−) +0.5V to (V+) − 0.5V.Therefore, choose the final A4 output:+0.5V ≤ VO4 ≤ +2.5VThis output results in a 2V range for the 3V VLOGOUTrange, or 2V/3V scaling factor.6.When I2 = 10mA, VLOGOUT = +1V, and VO4 = 2.5V.Using the equation in step 5:VO4+*SFACTOR ǒVLOGOUTǓ)VOFFSET2.5V+*2Vń3V(1V))VOFFSETTherefore, VOFFSET = 3.16V(12)I1+0.375 logI2ǒǓǒǓI1I2+)1.5VThe A4 amplifier configuration for VO4 = −2/3(VLOGOUT) +3.16 is seen in Figure 4a.The overall transer function is:VO4+*0.249 log+0.375 log1mAǒ10mAǓ+*1.5VForI2+100pA:VLOGOUT+0.375 log+0.375 log(8)Therefore, the expected voltage range at the outputof amplifier A3 is:*1.5VvVLOGOUTv)1.5V(9)ǒ1mA100pAǓ(13)A similar process can be used for configuring anexternal rail-to-rail output op amp, such as the OPA335.Because the OPA335 op amp can swing down to 0Vusing a pulldown resistor, RP, connected to −5V (fordetails, refer to the OPA335 data sheet, available fordownload at www.ti.com), the scaling factor is 2.5V/3Vand the corresponding VOFFSET is 3.3V. This circuitconfiguration is shown in Figure 4b.2ǒIIǓ)1.5V114LOG114www.ti.comSBOS301A − MAY 2004 − REVISED MARCH 2007InternalA4OutputAmplifierR5100kΩVLOGOUTR666.5kΩVLOGOUTR5100kΩExternalOutputAmplifierR682.5kΩ+5VA4VO4=−2/3(VLOGOUT)+3.16I210mA100pA2.5V0.5VVREF+2.5VOPA335VOUT=−2.5/3(VLOGOUT)+3.3RP(1)−5VI210mA100pA0.5V2.5VVREF+2.5VR7100kΩR8316kΩVO4R7100kΩR8267kΩVOUTa)A4amplifierusedtoscaleandoffsetVLOGOUTfor0.5Vto2.5Voutput.b)OPA335amplifierusedtoscaleandoffsetVLOGOUTfor0Vto2.5Voutput.NOTE:(1)SeeOPA335datasheetforuseofRPconnectedto−5Vtoachieve0Voutput.Figure 4. Operational Amplifier Configuration for Scaling and Offsetting the Output Going to ADC Stage.ADVANTAGES OF DUAL−SUPPLY OPERATIONThe LOG114 performs very well on a single +5V supplyby level-shifting pin 7 (Com) to half-supply and raisingthe common-mode voltage (pin 5, VCM IN) of the inputamplifiers. This level−shift places the input amplifiers inthe linear operating range. However, there are alsosome advantages to operating the LOG114 on dual ±5Vsupplies. These advantages include:1) eliminating the need for the +4.096V precisionreference;2) eliminating a small additional source of error arisingfrom the noise and temperature drift of the level−shiftingvoltage; and3) allowing increased magnitude of a reverse biasvoltage on the photodiode.COM (PIN 7) VOLTAGE RANGEThe voltage on the Com pin is used to bias the differen-tial amplifier, A3, within its linear range. This voltage canprovide an asymmetrical offset of the VLOGOUT voltage.VCM IN (Pin 5)The VCM IN pin is used to bias the A1 and A2 amplifier intoits common-mode input voltage range, (V−) + 1.5V to(V+) − 1.5V.INPUT CURRENT RANGETo maintain specified accuracy, the input current rangeof the LOG114 should be limited from 100pA to 3.5mA.Input currents outside of this range may compromisethe LOG114 performance. Input currents larger than3.5mA result in increased nonlinearity. An absolutemaximum input current rating of 10mA is included toprevent excessive power dissipation that may damagethe input transistor.15LOG114www.ti.comSBOS301A − MAY 2004 − REVISED MARCH 2007SETTING THE REFERENCE CURRENTWhen the LOG114 is used to compute logarithms, ei-ther I1 or I2 can be held constant to become the refer-ence current to which the other is compared.If IREF is set to the lowest current in the span of the signalcurrent (as shown in the front page figure), VLOGOUT willrange from:VLOGOUT+0.375 log10ply system, and a maximum value of 7mV in a +5V sup-ply system. Resistor temperature stability and noisecontributions should also be considered.ǒI1min^0VI1maxsignalǓVREF=100mV(14)R1+5VR2R3>>R2R31IREFVOS−+A1to some maximum value:VLOGOUT+0.375 log10IminǒImaxǓsignal11(15)While convenient, this approach does not usually resultin best performance, because I1 min accuracy is difficultto achieve, particularly if it is < 20nA.A better way to achieve higher accuracy is to chooseIREF to be in the center of the full signal range. Forexample, for a signal range of 1nA to 1mA, it is betterto use this approach:IREF+ISIGNALmin Ǹ1mAń1nA+1mAdc(16)Figure 5. T-Network for Reference Current.VREF may be an external precision voltage reference, orthe on-chip 2.5V voltage reference of the LOG114.IREF can be derived from an external current source,such as that shown in Figure 6.than it is to set IREF = 1nA. It is much easier and moreprecise (that is, dc accuracy, temperature stability, andlower noise) to establish a 1mA dc current level than a1nA level for the reference current.The reference current may be derived from a voltagesource with one or more resistors. When a single resis-tor is used, the value may be large depending on IREF.If IREF is 10nA and +2.5V is used:RREF = 2.5V/10nA = 250MΩA voltage divider may be used to reduce the value of theresistor, as shown in Figure 5. When using this method,one must consider the possible errors caused by theamplifier input offset voltage. The input offset voltage ofamplifier A1 has a maximum value of 4mV in a ±5V sup-2N2905RREF+15V6VIN8342N2905IREF3.6kΩ−15V6VRREFIREF=Figure 6. Temperature-Compensated Current Source.16LOG114www.ti.comSBOS301A − MAY 2004 − REVISED MARCH 2007NEGATIVE INPUT CURRENTSThe LOG114 functions only with positive input currents(conventional current flows into input current pins). InQAsituations where negative input currents are needed,the example circuits in Figure 7, Figure 8, and Figure 9may be used.IINQBNationalLM394D1D2OPA703IOUTFigure 7. Current Inverter/Current Source.+5V+3.3V1/2OPA23351.5kΩ1kΩ+5V1/2OPA233510nAto1mA(+3.3VBackBias)BSH20310nAto1mAPin3orPin4PhotodiodeLOG114Figure 8. Precision Current Inverter/Current Source.1kΩ100kΩ+5V10nAto1mA+3.3VBackBias+3.3VPhotodiode100kΩ1/2OPA2335+5V1.5kΩ1/2OPA23351.5kΩ100kΩ100kΩ10nAto1mAPin3orPin4LOG114Figure 9. Precision Current Inverter/Current Source.17LOG114www.ti.comSBOS301A − MAY 2004 − REVISED MARCH 2007VOLTAGE INPUTSThe LOG114 provides the best performance with cur-rent inputs. Voltage inputs may be handled directly byusing a low-impedance voltage source with series resis-tors, but the dynamic input range is limited to approxi-mately three decades of input voltage. This limitationexists because of the magnitude of the required inputvoltage and size of the corresponding series resistor.For 10nA of input current, a 10V voltage source and a1GΩ resistor would be required. Voltage and currentnoise from these sources must be considered and canlimit the usefulness of this technique.APPLICATION CIRCUITSLOG RATIOOne of the more common uses of log ratio amplifiers isto measure absorbance. See Figure 10 for a typical ap-plication. Absorbance of the sample is A = log λ1′/λ1. IfD1 and D2 are matched, A ∝ (0.375V) log(I1/I2).R5R69Q14I1D15I1VCMINA1VLOGOUT(1)10+IN410−IN4LOG114R1R2A4VO4(2)12Sampleλ1λ1λ1′Q23I2A2A3+IN513I2LightSourceD2R3R4A5VO51516VREF2.5VREFVREFGND1V+8+5VNOTES:(1)VLOGOUT=0.375×log(I1/I2).(2)VO4=0.375×K×log(I1/I2)K=1+R6/R5.V−6Com7−IN514Figure 10. Using the LOG114 to Measure Absorbance.18LOG114www.ti.comSBOS301A − MAY 2004 − REVISED MARCH 2007DATA COMPRESSIONIn many applications, the compressive effects of thelogarithmic transfer function are useful. For example, aLOG114 preceding a 12-bit ADC can produce thedynamic range equivalent to a 20-bit converter. (Sug-gested products: ADS7818, ADS7834).+3.3V OPERATIONFor systems with only a +3.3V power supply, theTPS60241 zero-ripple switched cap buck-boost 2.7V to5.5V input to 5V output converter may be used to gener-ate a +5V supply for the LOG114, as shown inFigure 11.Likewise, the TPS6040 negative charge pump may beconnected to the +5V output of the TPS60241 to gener-ate a −5V supply to create a ±5V supply for theLOG114, as Figure 12 illustrates.+3.3VC11µFC11µFI1VLOGOUTLOG114I2V+V−TPS60241VINC1+C1−GNDVOUTC2+C2−EN+5VC21µFC01µFFigure 11. Creating a +5V Supply from a +3.3V Supply.I1VLOGOUTLOG114I2V++5VV−−5VCFLY1µFTPS60241+3.3VC11µFC11µFVINC1+C1−GNDVOUTC2+C2−EN+5VC21µFCO1µFINCI1µFCFLY−CFLY+OUT−5VCO1µFTPS60400GNDFigure 12. Creating a ±5V Supply from a +3.3V Supply.19LOG114www.ti.comSBOS301A − MAY 2004 − REVISED MARCH 2007ERBIUM-DOPED FIBER OPTIC AMPLIFIER(EDFA)The LOG114 was designed for optical networking sys-tems. Figure 13 shows a block diagram of the LOG114in a typical EDFA application. This application uses twolog amps to measure the optical input and output powerof the amplifier. A difference amplifier subtracts the logoutput signals of both log amps and applies an errorvoltage to the proportional-integral-derivative (PID)controller. The controller output adjusts a voltage-con-trolled current source (VCCS), which then drives the pow-er op amp and pump laser. The desired optical gain isachieved when the error voltage at the PID is zero.The log ratio function is the optical power gain of theEDFA. This circuitry forms an automatic power levelcontrol loop.An alternate design of the system shown in Figure 13is possible because the LOG114 inherently takes thelog ratio. Therefore, one log amp can be eliminated byconnecting one of the photodiodes to the LOG114 I1input, and the other to the I2 input. The differentialamplifier would then be eliminated.The LOG114 is uniquely suited for most EDFAapplications because of its fast rise and fall times(typically less than 1µs for a 100:1 current input step).It also measures a very wide dynamic range of up toeight decades.Tap1%FiberTap1%PumpLaserOPA569PowerOpAmpILVCCSPIDVERRORI1LOG114DiffVOUT1VOUT2LOG114I2IREF1DACRREF1REFIREF2RREF2Figure 13. Erbium-Doped Fiber Optic Amplifier (EDFA) block diagram.20LOG114www.ti.comSBOS301A − MAY 2004 − REVISED MARCH 2007INSIDE THE LOG114The LOG114 uses two matched logarithmic amplifiers(A1 and A2 with logging diodes in the feedback loops) togenerate the outputs log (I1) and log (I2), respectively.The gain of 6.25 differential amplifier (A3) subtracts theoutput of A2 from the output of A1, resulting in [log (I1)− log (I2)], or log (I1/I2). The symmetrical design of theA1 and A2 logarithmic amps allows I1 and I2 to be usedinterchangeably, and provides good bandwidth andphase characteristics with frequency.DEFINITION OF TERMSTransfer FunctionThe ideal transfer function of the LOG114 is:VLOGOUT+0.375 logLog ConformityFor the LOG114, log conformity is calculated in thesame way as linearity and is plotted as I1/I2 on a semi-log scale. In many applications, log conformity is themost important specification. This condition is true be-cause bias current errors are negligible (5pA for theLOG114), and the scale factor and offset errors may betrimmed to zero or removed by system calibration.These factors leave log conformity as the major sourceof error.Log conformity is defined as the peak deviation from thebest fit straight line of the VLOGOUT versus log (I1/I2)curve. Log conformity is then expressed as a percent ofideal full−scale output. Thus, the nonlinearity error ex-pressed in volts over m decades is:VLOGOUT (NONLIN) = 0.375V/decade • 2Nmwhere N is the log conformity error, in percent.INDIVIDUAL ERROR COMPONENTSThe ideal transfer function with current input is:VLOGOUTIDEAL(17)This transfer function can be seen graphically in the typ-ical characteristic curve, VLOGOUT vs IREF.2ǒ1IǓ1When a pedestal, or offset, voltage (VCom) is connectedto the Com pin, an additional offset term is introducedinto the equation:VLOGOUT+0.375 logǒ1IǓ)V12Com(18)(19)The actual transfer function with the major componentsof error is:2+0.375 logǒ1IǓ1AccuracyAccuracy considerations for a log ratio amplifier aresomewhat more complicated than for other amplifiers.This complexity exists because the transfer function isnonlinear and has two inputs, each of which can varyover a widedynamic range. The accuracy for any combination ofinputs is determined from the total error specification.Total ErrorThe total error is the deviation of the actual output fromthe ideal output. Thus,VLOGOUT(ACTUAL) = VLOGOUT(IDEAL) ± Total ErrorIt represents the sum of all the individual componentsof error normally associated with the log amp when op-erating in the current input mode. The worst-case errorfor any given ratio of I1/I2 is the largest of the two errorswhen I1 and I2 are considered separately. Temperaturecan also affect total error.Errors RTO and RTIAs with any transfer function, errors generated by thefunction may be Referred-to-Output (RTO) or Referred-to-Input (RTI). In this respect, log amps have a uniqueproperty: given some error voltage at the log amp out-put, that error corresponds to a constant percent of theinput, regardless of the actual input level.0.375(1\"DK) logwhere:ǒIIǓ\"2Nm\"V12OSO(20)∆K = gain error (0.4%, typ, as specified in the Electri-cal Characteristics table)IB1 = bias current of A1 (5pA, typ)IB2 = bias current of A2 (5pA, typ)m = number of decades over which the logconformity error is specifiedN = log conformity error (0.1%, typ for m = 5 decades;0.9% typ for m = 7.5 decades)VOSO = output offset voltage (11mV, typ for ±5V sup-plies; 14mV, typ for +5V supplies)To determine the typical error resulting from these errorcomponents, first compute the ideal output. Then calcu-late the output again, this time including the individualerror components. Then determine the error in percentusing Equation (21):%error+ŤVLOGOUTIDEAL*VLOGOUTTYPŤVLOGOUTIDEAL 100%(21)21LOG114www.ti.comSBOS301A − MAY 2004 − REVISED MARCH 2007For example, in a system configured for measurementof five decades, with I1 = 1mA, and I2 = 10µA:VLOGOUTVLOGOUT10*3+0.75V+0.375 logIDEAL10*5TYPǒǓ(22)+0.375(1\"0.004) log\"2(0.001)(5)\"0.011ǒ1010−3*5 10−12−5*5 10−12ǓThe QFN package can be easily mounted using stan-dard printed circuit board (PCB) assembly techniques.See Application Note QFN/SON PCB Attachment(SLUA271) and Application Report Quad Flatpack No−Lead Logic Packages (SCBA017), both available fordownload at www.ti.com.The exposed leadframe die pad on the bottom ofthe package should be connected to V−.QFN LAYOUT GUIDELINESThe exposed leadframe die pad on the QFN packageshould be soldered to a thermal pad on the PCB. A me-chanical drawing showing an example layout is at-tached at the end of this data sheet. Refinements to thislayout may be necessary based on assembly processrequirements. Mechanical drawings located at the endof this data sheet list the physical dimensions for thepackage and pad. The five holes in the landing patternare optional, and are intended for use with thermal viasthat connect the leadframe die pad to the heatsink areaon the PCB.Soldering the exposed pad significantly improvesboard-level reliability during temperature cycling, keypush, package shear, and similar board-level tests.Even with applications that have low-power dissipation,the exposed pad must be soldered to the PCB to pro-vide structural integrity and long-term reliability.(23)Using the positive error components (+∆K, +2Nm, and+VOSO) to calculate the maximum typical output:VLOGOUTTYP+0.774V(24)Therefore, the error in percent is:%error+|0.75*0.774| 100%+3.2%0.75(25)QFN PACKAGEThe LOG114 comes in a QFN-16 package. This lead-less package has lead contacts on all four sides of thebottom of the package, thereby maximizing boardspace. An exposed leadframe die pad on the bottom ofthe package enhances thermal and electrical charac-teristics.QFN packages are physically small, have a smallerrouting area, improved thermal performance, and im-proved electrical parasitics. Additionally, the absence ofexternal leads eliminates bent-lead issues.22PACKAGEOPTIONADDENDUM
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PACKAGINGINFORMATION
OrderableDeviceLOG114AIRGVRLOG114AIRGVRG4LOG114AIRGVTLOG114AIRGVTG4
(1)
Status(1)ACTIVEACTIVEACTIVEACTIVE
PackageTypeVQFNVQFNVQFNVQFN
PackageDrawingRGVRGVRGVRGV
PinsPackageEcoPlan(2)
Qty16161616
2500Green(RoHS&
noSb/Br)2500Green(RoHS&
noSb/Br)250250
Green(RoHS&noSb/Br)Green(RoHS&noSb/Br)
Lead/BallFinishCUNIPDAUCUNIPDAUCUNIPDAUCUNIPDAU
MSLPeakTemp(3)Level-2-260C-1YEARLevel-2-260C-1YEARLevel-2-260C-1YEARLevel-2-260C-1YEAR
Themarketingstatusvaluesaredefinedasfollows:ACTIVE:Productdevicerecommendedfornewdesigns.
LIFEBUY:TIhasannouncedthatthedevicewillbediscontinued,andalifetime-buyperiodisineffect.
NRND:Notrecommendedfornewdesigns.Deviceisinproductiontosupportexistingcustomers,butTIdoesnotrecommendusingthispartinanewdesign.
PREVIEW:Devicehasbeenannouncedbutisnotinproduction.Samplesmayormaynotbeavailable.OBSOLETE:TIhasdiscontinuedtheproductionofthedevice.
(2)
EcoPlan-Theplannedeco-friendlyclassification:Pb-Free(RoHS),Pb-Free(RoHSExempt),orGreen(RoHS&noSb/Br)-pleasecheckhttp://www.ti.com/productcontentforthelatestavailabilityinformationandadditionalproductcontentdetails.TBD:ThePb-Free/Greenconversionplanhasnotbeendefined.
Pb-Free(RoHS):TI'sterms\"Lead-Free\"or\"Pb-Free\"meansemiconductorproductsthatarecompatiblewiththecurrentRoHSrequirementsforall6substances,includingtherequirementthatleadnotexceed0.1%byweightinhomogeneousmaterials.Wheredesignedtobesolderedathightemperatures,TIPb-Freeproductsaresuitableforuseinspecifiedlead-freeprocesses.
Pb-Free(RoHSExempt):ThiscomponenthasaRoHSexemptionforeither1)lead-basedflip-chipsolderbumpsusedbetweenthedieandpackage,or2)lead-baseddieadhesiveusedbetweenthedieandleadframe.ThecomponentisotherwiseconsideredPb-Free(RoHScompatible)asdefinedabove.
Green(RoHS&noSb/Br):TIdefines\"Green\"tomeanPb-Free(RoHScompatible),andfreeofBromine(Br)andAntimony(Sb)basedflameretardants(BrorSbdonotexceed0.1%byweightinhomogeneousmaterial)
(3)
MSL,PeakTemp.--TheMoistureSensitivityLevelratingaccordingtotheJEDECindustrystandardclassifications,andpeaksoldertemperature.
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Addendum-Page1
PACKAGEMATERIALSINFORMATION
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TAPEANDREELINFORMATION
*Alldimensionsarenominal
Device
PackagePackagePinsTypeDrawingVQFNVQFN
RGVRGV
1616
SPQ
ReelReelA0DiameterWidth(mm)(mm)W1(mm)330.0180.0
12.412.4
4.254.25
B0(mm)4.254.25
K0(mm)1.151.15
P1(mm)8.08.0
WPin1(mm)Quadrant12.012.0
Q2Q2
LOG114AIRGVRLOG114AIRGVT
2500250
PackMaterials-Page1
PACKAGEMATERIALSINFORMATION
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*Alldimensionsarenominal
DeviceLOG114AIRGVRLOG114AIRGVT
PackageType
VQFNVQFN
PackageDrawing
RGVRGV
Pins1616
SPQ2500250
Length(mm)
346.0190.5
Width(mm)346.0212.7
Height(mm)
29.031.8
PackMaterials-Page2
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applicationsusingTIcomponents.Tominimizetherisksassociatedwithcustomerproductsandapplications,customersshouldprovideadequatedesignandoperatingsafeguards.
TIdoesnotwarrantorrepresentthatanylicense,eitherexpressorimplied,isgrantedunderanyTIpatentright,copyright,maskworkright,orotherTIintellectualpropertyrightrelatingtoanycombination,machine,orprocessinwhichTIproductsorservicesareused.InformationpublishedbyTIregardingthird-partyproductsorservicesdoesnotconstitutealicensefromTItousesuchproductsorservicesorawarrantyorendorsementthereof.Useofsuchinformationmayrequirealicensefromathirdpartyunderthepatentsorotherintellectualpropertyofthethirdparty,oralicensefromTIunderthepatentsorotherintellectualpropertyofTI.
ReproductionofTIinformationinTIdatabooksordatasheetsispermissibleonlyifreproductioniswithoutalterationandisaccompaniedbyallassociatedwarranties,conditions,limitations,andnotices.Reproductionofthisinformationwithalterationisanunfairanddeceptivebusinesspractice.TIisnotresponsibleorliableforsuchaltereddocumentation.Informationofthirdpartiesmaybesubjecttoadditionalrestrictions.
ResaleofTIproductsorserviceswithstatementsdifferentfromorbeyondtheparametersstatedbyTIforthatproductorservicevoidsallexpressandanyimpliedwarrantiesfortheassociatedTIproductorserviceandisanunfairanddeceptivebusinesspractice.TIisnotresponsibleorliableforanysuchstatements.
TIproductsarenotauthorizedforuseinsafety-criticalapplications(suchaslifesupport)whereafailureoftheTIproductwouldreasonablybeexpectedtocauseseverepersonalinjuryordeath,unlessofficersofthepartieshaveexecutedanagreementspecificallygoverningsuchuse.Buyersrepresentthattheyhaveallnecessaryexpertiseinthesafetyandregulatoryramificationsoftheirapplications,and
acknowledgeandagreethattheyaresolelyresponsibleforalllegal,regulatoryandsafety-relatedrequirementsconcerningtheirproductsandanyuseofTIproductsinsuchsafety-criticalapplications,notwithstandinganyapplications-relatedinformationorsupportthatmaybeprovidedbyTI.Further,BuyersmustfullyindemnifyTIanditsrepresentativesagainstanydamagesarisingoutoftheuseofTIproductsinsuchsafety-criticalapplications.
TIproductsareneitherdesignednorintendedforuseinmilitary/aerospaceapplicationsorenvironmentsunlesstheTIproductsarespecificallydesignatedbyTIasmilitary-gradeor\"enhancedplastic.\"OnlyproductsdesignatedbyTIasmilitary-grademeetmilitary
specifications.BuyersacknowledgeandagreethatanysuchuseofTIproductswhichTIhasnotdesignatedasmilitary-gradeissolelyattheBuyer'srisk,andthattheyaresolelyresponsibleforcompliancewithalllegalandregulatoryrequirementsinconnectionwithsuchuse.TIproductsareneitherdesignednorintendedforuseinautomotiveapplicationsorenvironmentsunlessthespecificTIproductsaredesignatedbyTIascompliantwithISO/TS16949requirements.Buyersacknowledgeandagreethat,iftheyuseanynon-designatedproductsinautomotiveapplications,TIwillnotberesponsibleforanyfailuretomeetsuchrequirements.
FollowingareURLswhereyoucanobtaininformationonotherTexasInstrumentsproductsandapplicationsolutions:ProductsAmplifiersDataConvertersDLP®ProductsDSP
ClocksandTimersInterfaceLogicPowerMgmtMicrocontrollersRFID
amplifier.ti.comdataconverter.ti.comwww.dlp.comdsp.ti.comwww.ti.com/clocksinterface.ti.comlogic.ti.compower.ti.commicrocontroller.ti.comwww.ti-rfid.com
ApplicationsAudioAutomotive
CommunicationsandTelecomComputersandPeripherals
ConsumerElectronicsEnergyIndustrialMedicalSecurity
Space,Avionics&Defense
VideoandImagingWireless
www.ti.com/audiowww.ti.com/automotivewww.ti.com/communicationswww.ti.com/computerswww.ti.com/consumer-appswww.ti.com/energywww.ti.com/industrialwww.ti.com/medicalwww.ti.com/security
www.ti.com/space-avionics-defensewww.ti.com/videowww.ti.com/wireless-apps
RF/IFandZigBee®Solutionswww.ti.com/lprf
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