LT1073 - Micropower DC/DC Converter Adjustable …

1 LT10731 TYPICAL APPLICATION FEATURESDESCRIPTIONM icropower DC/DC Converter Adjustable and Fixed 5V, 12 VThe LT 1073 is a versatile Micropower DC/DC Converter . The device requires only three external components to deliver a fixed output of 5V or 12V. The very low minimum supply voltage of 1V allows the use of the LT1073 in applications where the primary power source is a single cell. An on-chip auxiliary gain block can function as a low-battery detector or linear current drain of the LT1073 -5 used as shown in the Typical Application circuit below is just 135 A unloaded, making it ideal for applications where long battery life is important.

2 The circuit shown can deliver 5V at 40mA from an input as low as and 5V at 10mA from a 1V device can easily be configured as a step-up or step-down Converter , although for most step-down applications or input sources greater than 3V, the LT1173 is recom-mended. Switch current limiting is user- Adjustable by adding a single external resistor. Unique reverse-battery protection circuitry limits reverse current to safe, non-destructive levels at reverse supply voltages up to nNo Design Required nOperates at Supply Voltages from 1V to 30V nConsumes Only 95 A Supply Current nWorks in Step-Up or Step-Down Mode nOnly Three External Off-the-Shelf Components Required nLow-Battery Detector Comparator On-Chip nUser- Adjustable Current Limit nInternal 1A Power Switch nFixed or Adjustable Output Voltage Versions nSpace-Saving 8-Pin PDIP or SO-8 Package nPagers nCameras nSingle-Cell to 5V Converters nBattery Backup

3 Supplies nLaptop and Palmtop Computers nCellular Telephones nPortable Instruments n4mA to 20mA Loop Powered Instruments nHand-Held Inventory Computers nBattery-Powered , , and Particle DetectorsL, LTC, and LT are registered trademarks of Linear Technology to 5V ConverterSingle Alkaline AA Cell Operating Hours vs DC Load Current+1N58185V40mA100 FSANYO0S-CON1073 CELL*CADDELL-BURNS7300-1282 HOPERATES WITH CELL VOLTAGE 1 VADD 10 F DECOUPLING CAPACITOR IF BATTERY IS MORE THAN 2" AWAY FROM LT1073 *LOAD CURRENT (mA)1 CONTINUOUS OPERATION (HOURS)100010010110100LT1073 TA02L = 180 HL = 82 HLT10732 PIN CONFIGURATIONABSOLUTE MAXIMUM RATINGSS upply Voltage, Step-Up Mode.

4 15 VSupply Voltage, Step-Down Mode ..36 VSW1 Pin Voltage ..50 VSW2 Pin Voltage .. to VINF eedback Pin Voltage ( LT1073 ) ..5 VSwitch Current .. Power Dissipation ..500mWOperating Temperature Range ..0 C to 70 CStorage Temperature Range .. 65 C to 150 CLead Temperature (Soldering, 10 sec) ..300 C(Note 1)ELECTRICAL CHARACTERISTICSSYMBOLPARAMETERCONDITIONS MINTYPMAXUNITSIQQ uiescent CurrentSwitch Offl95130 AIQQ uiescent Current, Step-Up Mode ConfigurationNo LoadLT1073-5 LT1073 -12135 250 A AVINI nput VoltageStep-Up VStep-Down Model30 VComparator Trip Point VoltageLT1073 (Note 2)l202212222mVVOUTO utput Sense VoltageLT1073-5 (Note 3) LT1073 -12 (Note 3)

5 L VComparator HysteresisLT1073l510mVOutput HysteresisLT1073-5 LT1073 -12l l125 300250 600mV mVfOSCO scillator Frequencyl151923kHzDCDuty CycleFull Load (VFB = VREF)l657280%tONSwitch ON Timel303850 sIFBF eedback Pin Bias CurrentLT1073, VFB = 0Vl1050nAISETSet Pin Bias CurrentVSET = VREFl60120nAVAOAO Output LowIAO = 100 Line Regulation1V VIN VIN 12Vl %VVCESATS witch Saturation Voltage Set-Up ModeVIN = , ISW = 400mA l300400 600mV mVVIN = , ISW = 500mA l400550 750mV mVVIN = 5V, ISW = 1A l7001000 1500mV mVAVA2 Error Amp GainRL = 100k (Note 4)

6 L4001000V/V The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25 C. VIN = unless otherwise VIEWILIMVINSW1SW2FB (SENSE)*SETA0 GNDN8 PACKAGE8-LEAD PDIPS8 PACKAGE8-LEAD PLASTIC SO*FIXED VERSIONS TJMAX = 125 C, JA = 100 C/W (N8) TJMAX = 125 C, JA = 120 C/W (S8)ORDER PART NUMBERLT1073CN8LT1073CN8-5LT1073CN8-12LT 1073CS8LT1073CS8-5LT1073CS8-12S8 PART MARKING107310735107312 Consult factory for parts specified with wider operating temperature CHARACTERISTICSNote 1: Absolute Maximum Ratings are those values beyond which the life of a device may be 2.

7 This specification guarantees that both the high and low trip point of the comparator fall within the 202mV to 222mV 3: This specification guarantees that the output voltage of the fixed versions will always fall within the specified range. The waveform at the SENSE pin will exhibit a sawtooth shape due to the comparator 4: 100k resistor connected between a 5V source and the AO 5: The LT1073 is guaranteed to withstand continuous application of applied to the GND and SW2 pins while VIN, ILIM and SW1 pins are Battery Current(Note 5)

8 750mAILIMC urrent Limit220 Between ILIM and VIN400mACurrent Limit Temperature Coefficient CILEAKS witch OFF Leakage CurrentMeasured at SW1 Pin110 AVSW2 Maximum Excursion Below GNDISW1 10 A, Switch Off 400 350mV The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25 C.

9 VIN = unless otherwise PERFORMANCE CHARACTERISTICSS aturation Voltage Step-Up Mode (SW2 Pin Grounded)Switch ON Voltage Step-Down Mode (SW1 Pin Connected to VIN)Maximum Switch Current vs RLIMFB Pin Bias Current vs TemperatureSET Pin Bias Current vs Temperature Gain Block GainISWITCH (A)0 VCESAT (V) = = = 5 VVIN = 2 VVIN = 1 VVIN = 3 VTEMPERATURE ( C) 50FB BIAS CURRENT (nA)1001073 G04050201816141210864 252575125 ISWITCH (A)0 SWITCH ON VOLTAGE (V) ( C) 50 SET PIN BIAS CURRENT (nA)1001073 G050502001751501251007550250 252575125 RLIM ( )10 SWITCH CURRENT (mA)120011001000900800700600500400300200 10010010001073 G03L = 82 HVIN = 3 VVIN = ( C) 50GB GAIN (V/V)1001073 G06050180016001400120010008006004002000 252575125 VIN = = 100kLT10734 +A1A2 COMPARATORDRIVER212mVREFERENCEOSCILLATOR GAIN BLOCK/ERROR AMPVINSETA0 ILIMSW1Q1SW2 FBGND1073 BD01 +A1A2 COMPARATORDRIVER212mVREFERENCEOSCILLATOR GAIN BLOCK/ERROR AMPVINSETA0 ILIMSW1Q1SW2 GND1073 BD02R1R2940kSENSELT1073-5: R1 = 40kLT1073-12.

10 R2 = PERFORMANCE CHARACTERISTICSS upply Current vs TemperatureRecommended Minimum Inductance ValueGuaranteed Minimum Output Current at 5V vs VINTEMPERATURE ( C) 50 SUPPLY CURRENT ( A)1001073 G070501501401301201101009080706050 252575125 VIN = VOLTAGE (V)MINIMUM INDUCTANCE ( H)1073 = 0 VVIN (V) CURRENT (mA) G09 FOR VIN > A68 RESISTORMUST BE CONNECTED BETWEEN ILIM AND VINPIN FUNCTIONSBLOCK DIAGRAMSILIM (Pin 1): Connect this pin to VIN for normal use. Where lower current limit is desired, connect a resistor between ILIM and VIN.