LTC1923 - High Efficiency Thermoelectric Cooler Controller

1 1 LTC19231923fHigh Efficiency ThermoelectricCooler ControllernHigh Efficiency , Low Noise TopologynAdjustable Output Slew Rate Reduces EMInFull-Bridge Controller for BidirectionalCurrent ControlnAdjustable Pulse-by-Pulse Bidirectional TECC urrent LimitnOpen/Shorted Thermistor IndicationnSolution Footprint in Less Than " "(Double-Sided PCB)nAvailable in 5mm x 5mm QFN and28-Pin SSOP PackagesnTEC Voltage ClampingnTEC Current, Voltage and Heat/Cool Status OutputsnAdjustable/Synchronizable Oscillator FrequencyReduces Filter Component Size and System Reference Voltage Minimum Operating Voltage.

2 LTC and LT are registered trademarks of Linear Technology Fiber Optic LinksnMedical InstrumentsnCPU Temperature RegulatorsLaser Temperature Control Loop Achieving Setpoint Stability of CThe LTC 1923 is a pulse width modulator intended forthermoelectric Cooler (TEC) or heater applications requir-ing either unidirectional or bidirectional drive circuits. Allof the necessary control circuitry and two sets of comple-mentary output drivers are integrated into the LTC1923 todrive a full bridge, providing an efficient means of bidirec-tional current flow to the TEC.

3 An accurate temperaturecontrol loop to stabilize the temperature of a laser diodesystem is easily achieved with the addition of just a fewexternal components. Typical temperature setpoint accu-racy of C is achievable with the LTC1923 . Adding aninstrumentation amplifier front end allows setpoint stabil-ity of part features independent adjustable heating andcooling pulse-by-pulse current limit, current soft-start forcontrolled start-up, output slew rate control to reducesystem noise, differential current sense and voltage am-plifiers and a host of auxiliary circuits to protect the laserand provide redundant system +CS ITECTEC+TEC LTC1923 VDD +LTC2053A = F10 FL110 HVDDRSC1, C2: TAIYO YUDEN JMK325BJ226MM-T (X7R)L1, L2.

4 SUMIDA CDRH6D2B-220NC*MNA, MPA: SILICONIX Si9801**MNB, MPB: SILICONIX Si98011923 F1 F10M100k10k1 FL210 HC122 FC222 FMPA*VREFMPB**MNA*MNB**TECCOOLER82kAPPLI CATIO SUFEATURESTYPICAL APPLICATIOUDESCRIPTIOU2 LTC19231923fVDD to GND .. to 6 VSDSYNC, to 6 VFB, CNTRL, VTHRM, ILIM, to 6 VCS+, CS , TEC+, TEC .. to 6 VORDER PARTNUMBERLTC1923 EGNTJMAX = 125 C, JA = 120 C/WABSOLUTE AXI U RATI GSWWWUPACKAGE/ORDER I FOR ATIOUUWThe l denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25 = 5V, RSLEW = VDD, SDSYNC = VDD, RT = 10k.

5 CT = 330pF unless otherwise CHARACTERISTICS1234567891011121314 TOP VIEWGN PACKAGE28-LEAD PLASTIC SSOP2827262524232221201918171615 PLLLPFRSLEWSDSYNCCNTRLEAOUTFBAGNDSSILIMV SETFAULTVTHRMH/CVTECRTCTVREFPDRVBNDRVBVD DPGNDNDRVAPDRVACS+CS ITECTEC+TEC Consult LTC Marketing for parts specified with wider operating temperature ranges.(Note 1)FAULT, H/C .. to 6 VOperating Temperature Range (Note 2) .. 40 C to 85 CStorage Temperature Range .. 65 C to 125 CLead Temperature (Soldering, 10 sec) .. 300 CORDER PARTNUMBERLTC1923 EUH3231302928272625910111213141516171819 202122232487654321 CNTRLEAOUTFBAGNDNCSSILIMVSETPDRVBNDRVBVD DVDDPGNDNDRVAPDRVACS+SDSYNCRSLEWPLLLPFRT CTVREFNCNCFAULTVTHRMH/CVTECTEC TEC+ITECCS UH PACKAGE32-LEAD PLASTIC QFNPIN 1 TOP VIEWTJMAX = 125 C, JA = 34 C/WEXPOSED PAD IS PGND(MUST BE SOLDERED TO PCB)

6 SYMBOLPARAMETERCONDITIONSMINTYPMAXUNITSI nput SupplyVDDO perating Supply LockoutLow to High to Lowl50130mVIDDO perating Supply CurrentNo Output Load, Outputs Not Switching24mAIDDSHDNS hutdown IDDSDSYNC = 0V1025 ASHDNTHS hutdown ThresholdMeasured at PDRVA, l denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25 = 5V, RSLEW = VDD, SDSYNC = VDD, RT = 10k, CT = 330pF unless otherwise CHARACTERISTICSSYMBOLPARAMETERCONDITIONS MINTYPMAXUNITSR eferenceVREFR eference Output VoltageNo Good ThresholdVREF Rising RegulationILOAD = 1mA to 10mA1025mVLINEREG Line RegulationVDD = to CurrentVREF = 0V1020mAOscillator and Phase-Locked LoopfOSCII nitial Oscillator FrequencyRT = 10k, CT = 330pF190225260kHzfOSCF requency VariationVDD = to 5V, CT = 330pF, RT = 10kl165225270kHzOSCPKCT Ramp Ramp Charge CurrentCT =.

7 RT = 10k 150 ACTIDISCT Discharge CurrentCT = , RT = 10k150 APLLGAIN Gain from PLLLPF to RT Detector Output Current SinkingfSYNC < fOSC12 A SourcingfSYNC > fOSC 12 AMSTTHM aster Threshold On PLLLPF PinMeasured at SDSYNC PinVDD VDD Delay to Output2045 sError AmplifierVOSI nput Offset VoltageEAOUT = 1V, VCM = 1818mVAOLOpen-Loop GainEAOUT = to , CNTRL = Mode Input RangeEAOUT = + and CNTRL Input Bias CurrentsFB = CNTRL = 100100nAVOHO utput HighILOAD = 100 LowILOAD = 100 CurrentEAOUT = 1V, FB = , CNTRL = CurrentEAOUT = 1V, FB = 5V, CNTRL = Productf = 100kHz (Note 3)2 MHzCurrent Sense AmplifierACSA mplifier Gain10V/VCSOFFA mplifier OffsetMeasured at ITEC 15 210mVITECHO utput Sourcing Load RegulationCS+ - CS = 100mV, ILOAD = 0 to 50 Sinking Load RegulationCS+ - CS = 100mV, ILOAD = 0 to 50 3dB Frequency(Note 3)

8 500kHzILIMTHC urrent Limit ThresholdMeasured at CS+, CS l125145165mVILIMDLYC urrent Limit Delay to Output300450nsSSICHGSoft-Start Charge CurrentSS = ASSILIMSoft-Start Current Limit ThresholdSS = , Measured at CS+, CS 507090mVILIMILIM Current Limit ThresholdILIM = , Measured at CS+, CS 507090mV4 LTC19231923fNote 1: Absolute Maximum Ratings are those values beyond which the lifeof a device may be 2: The LTC1923E is guaranteed to meet specifications from 0 C to70 C. Specifications over the 40 C to 85 C operating temperature rangeare assured by design, characterization and correlation with statisticalprocess CHARACTERISTICSNote 3.

9 Guaranteed by design, not tested in l denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25 = 5V, RSLEW = VDD, SDSYNC = VDD, RT = 10k, CT = 330pF unless otherwise Voltage AmplifierATECA mplifier OffsetMeasured at VTEC, VCM = 7mVTECCMRC ommon Mode < VCM < High VoltageILOAD = 50 Low VoltageILOAD = 50 3dB Frequency(Note 3)1 MHzOutput DriversOUTHO utput High VoltageIOUT = Low VoltageIOUT = Rise TimeCLOAD = 1nF20nstFALLO utput Fall TimeCLOAD = 1nF20nstrSLEWO utput Rise TimeCLOAD = 1nF, RSLEW = 10k20nstfSLEWO utput Fall TimeCLOAD = 1nF, RSLEW = 10k20nstrSLEWO utput Rise TimeCLOAD = 1nF, RSLEW = 100k90nstfSLEWO utput Slew Fall TimeCLOAD = 1nF, RSLEW = 100k90nsSLEWVTRSLEW Disable Dead TimeRT = 10k90nsFaultOPENTHOpen Thermistor ThresholdVSET = 5V.

10 Measured with Respect to VSET 410mVSHRTTHS horted Thermistor ThresholdVSET = 5V, Measured with Respect to Output Low Voltage1mA Into FAULT, During Fault150300mVDirection ComparatorDIRHLow-to-High ThresholdTEC = , Measured with Respect to TEC 50mVSensed When H/C Toggles LowDIRLHigh-to-Low ThresholdTEC = , Measured with Respect to TEC 50mVSensed When H/C Toggles HighHCVH/C Output Low Voltage1mA Into Pin150300mV5 LTC19231923fTEMPERATURE ( C) 50165 OSCILLATOR FREQUENCY (kHz)185205225265 201040701923 G01100130245CT = 330pFRT = 10kRT (k )50 OSCILLATOR FREQUENCY (kHz)20060080010001518001923 G024001020120014001600CT = 68pFCT = 150pFCT = 330pFVDD = , 5 VTA = 25 CTEMPERATURE ( C)VREF (V) 50 20104070100130 TYPICAL PERFOR A CE CHARACTERISTICS UWVREF vs IREF for DifferentTemperaturesOutput Dead Time vs RTError Amplifier Offset Voltagevs TemperatureOpen Thermistor Thresholdvs TemperatureOutput Rise/Fall Time vs RSLEWS horted Thermistor Thresholdvs TemperatureIREF (mA)0 VREF (V)