LTC1502-3.3 LINER
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LTC1502-3.3 Single Cell to 3.3V Regulated Charge Pump DC/DC Converter n Input Voltage Range: 0.9V to 1.8V n 0.9V Guaranteed Start-Up Voltage n Regulated Output Voltage: 3.3V –4% n Output Current: 10mA (VIN ‡ 1V) n No Inductors n Shutdown Disconnects Load from VIN n Low Operating Current: 40mA n Low Shutdown Current: 5mA n Short-Circuit and Overtemperature Protected n Application Circuit Fits in < 0.125in2 PCB Area n Available in 8-Pin MSOP and SO Packages The LTC 1502-3.3 is a quadrupler charge pump DC/DC converter that produces a regulated 3.3V output from a single alkaline cell input. It requires only five small external capacitors—no inductors are required. Low supply cur- rent (40mA typical, 5mA in shutdown) and minimal external components make the LTC1502-3.3 ideal for space and power conscious single-cell applications. The total printed circuit board area of the circuit shown below is less than 0.125in Forcing the C1–/SHDN pin low through an external resis- tive pull-down puts the part into shutdown mode. During shutdown, the internal oscillator is stopped and the load is disconnected from V IN. An internal pull-up current on the C1–/SHDN pin forces the part back into normal operation once the pull-down resistance is removed. The LTC1502-3.3 is short-circuit protected and survives an indefinite V OUT short to ground. The LTC1502-3.3 is available in 8-pin MSOP and SO packages. , LTC and LT are registered trademarks of Linear Technology Corporation. Output Voltage vs Input Voltage 1502-3.3 TA01 1mF 6 5VINGND 1mF VIN SINGLE CELL NiCd or ALKALINE 10mF 10mF 10mF VOUT = 3.3V IOUT = 10mA LTC1502-3.3 C1+ C1–/SHDN VOUT C3+ C3– Single Cell to 3.3V DC/DC Converter n Pagers n Battery Backup Supplies n Portable Electronic Equipment n Handheld Medical Instruments n Glucose Meters INPUT VOLTAGE (V) 0.8 OUTPUT VOLTAGE (V) 3.3 3.4 3.5 1.6 1502-3.3 TA02 3.2 3.1 3.0 1.0 1.2 1.4 1.8 TA = 25°C IOUT = 10mA IOUT = 15mA FEATURES DESCRIPTIO U APPLICATIO SU TYPICAL APPLICATIO U PCB LAYOUT FITS IN <0.125IN2
LTC1502-3.3 ABSOLUTE MAXIMUM RATINGSW WW U Operating Temperature Range (Note 1) PACKAGE/ORDER INFORMATIONW UU ORDER PART NUMBER ORDER PART NUMBER LTC1502CS8-3.3 LTC1502IS8-3.3 S8 PART MARKING Consult factory for Military grade parts. TJMAX = 125°C, qJA = 150°C/ W LTC1502CMS8-3.3 MS8 PART MARKING LTECTJMAX = 125°C, qJA = 250°C/ W C1–/SHDN GND V OUT C3+ C3– VIN TOP VIEW MS8 PACKAGE 8-LEAD PLASTIC MSOP TOP VIEW VOUT C3+ C3– VIN C1+ C1–/SHDN GND S8 PACKAGE 8-LEAD PLASTIC SO 150233 502I33
ELECTRICAL CHARACTERISTICS
PARAMETER CONDITIONS MIN TYP MAX UNITS VIN Operating Voltage l 0.9 1.8 V Minimum VIN Start-Up Voltage T A = 0°C to 70°C (Note 2) l 0.75 0.9 V TA = –40°C to 85°C (Note 2) l 1.1 V IOUT £ 10mA, 1V £ VIN £ 1.8V l 3.17 3.3 3.43 V VIN Operating Current I OUT = 0mA l 40 90 mA VIN Shutdown Current C1 –/SHDN = 0V l 51 5 mA Output Ripple I OUT = 10mA, VIN = 1.25V 50 mV P-P Efficiency V IN = 1V, IOUT = 10mA 77 % Switching Frequency Oscillator Free-Running 500 kHz C1–/SHDN Shutdown Input Threshold C1 –/SHDN in Hi-Z Sampling State l 0.20 0.55 0.85 V C1–/SHDN Shutdown Input Current C1 –/SHDN = 0V (Note 3) l –0.5 –2.5 –8 mA VOUT Turn-On Time V IN = 1V, IOUT = 0mA 5 ms VOUT Short-Circuit Current V IN = 1.5V, VOUT Forced to 0V 20 mA The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 0.9V to 1.8V, C1 = C3 = 1mF, CIN = C2 = COUT = 10mF unless otherwise specified. Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired. Note 2: Start-up testing is done with a 100kW equivalent load on VOUT. Note 3: Currents flowing into the device are positive polarity. Currents flowing out of the device are negative polarity. Note 4: Commercial grade specifications are guaranteed over the 0°C to 70°C operating temperature range. In addition, commercial grade specifications are assured over the –40°C to 85°C operating temperature range by design, characterization and correlation with statistical process controls. Industrial grade specifications are guaranteed and tested over the –40°C to 85°C operating temperature range.
LTC1502-3.3 TYPICAL PERFOR A CE CHARACTERISTICS UW INPUT VOLTAGE (V) 0.8 INPUT CURRENT (µA) 1.6 1502-3.3 G01 1.0 1.2 1.4 1.8 TA = 25°C TA = 0°C TA = – 40°C IOUT = 0mA TA = 70°C TA = 85°C No Load Input Current vs Input Voltage OUTPUT CURRENT (mA) 0.01 OUTPUT VOLTAGE (V) 3.30 3.35 TA = 25°C VIN = 1V 100 1502-3.3 G03 3.25 3.20 0.1 1 10 3.40 VIN = 1.5V VIN = 1.8V Output Voltage vs Output Current Shutdown Input Current vs Input Voltage INPUT VOLTAGE (V) 0.8 INPUT CURRENT (µA) 1.6 1502-3.3 G02 1.0 1.2 1.4 1.8 TA = 70°C TA = 85°C TA = 25°C TA = – 40°C TA = 0°C C1–/SHDN = 0V Maximum Start-Up Load Current vs Input Voltage INPUT VOLTAGE (V) 0.8 LOAD CURRENT (mA) 1.6 1502-3.3 G04 1.0 1.2 1.4 1.8 TA = 25°C Load Transient Response 200ms/DIV IOUT 0mA to 10mA 5mA/DIV VOUT AC COUPLED 50mV/DIV Efficiency vs Output Current OUTPUT CURRENT (mA) 0.01 EFFICIENCY (%) 100 1502-3.3 G05 0.1 1 10 100 TA = 25°C VOUT = 3.3V VIN = 1V VIN = 1.25V VIN = 1.5V VIN = 1.8V 1502-3.3 G06 Oscillator Frequency vs Input Voltage Shutdown Waveforms (See Figure 1) Calculated Battery Life, Battery = 2400mA • Hr AA Cell INPUT VOLTAGE (V) 0.8 OSCILLATOR FREQUENCY (kHz) 500 600 1.6 1502-3.3 G07 400 300 1.0 1.2 1.4 1.8 700 TA = 70°C TA = – 40°C TA = 25°C TA = 85°C TA = 0°C AVERAGE LOAD CURRENT (mA) 0.001 BATTERY LIFE (HOURS) 100k 0.1 1 100.01 100 1502-3.3 G08 100 10k 100ms/DIV VOUT 2V/DIV OFF 1502-3.3 G09 ON VIN = 1.25V RLOAD = 10k TA = 25°C VCTRL VIN = 1.25V TA = 25°C
LTC1502-3.3 GND (Pin 4): Ground. Connect to a ground plane for best performance. VIN (Pin 5): Input Supply Voltage. Bypass VIN with a ‡10mF low ESR capacitor to ground. C3– (Pin 6): Charge Pump 2 (CP2) Flying Capacitor Negative Terminal. C3+ (Pin 7): Charge Pump 2 Flying Capacitor Positive Terminal. VOUT (Pin 8): 3.3V Regulated Output Voltage. V OUT is disconnected from V IN during shutdown. Bypass V OUT with a ‡ 10mF low ESR capacitor to ground. PIN FUNCTIONSUU U C2 (Pin 1): Charge Pump 1 (CP1) Output. This pin also serves as the input supply for charge pump 2 (CP2). To ensure proper start-up, the C2 pin must not be externally loaded. Bypass the C2 pin with a ‡ 10mF low ESR capacitor to ground. + (Pin 2): Charge Pump 1 Flying Capacitor Positive Terminal. C1–/SHDN (Pin 3): Charge Pump 1 Flying Capacitor Nega- tive Terminal and Shutdown Input. Pulling this pin to ground through a » 100W resistor will put the part into shutdown mode. With a high resistance pull-down FET, the series resistor may be eliminated. The external pull- down device must be high impedance for normal opera- tion (see Applications Information). Peak voltage present on this pin is approximately equal to V IN. BLOCK DIAGRAMW TIMING CONTROL BIAS CONTROL 1.2V REF CP2 C3C1 CP1 SHDN OSCEN INTERNAL VCC CLK1/CLK2 VOUT HIZ2 HIZ1 1M 1.2M 2.1M COUT COMP2COMP3 COMP1 400k 0.55V 2.5µA C1–/SHDN SHUTDOWN C1+ C3– C3+ VIN 1 6 7 VOUT8 VIN GND 1502-3.3 BD CIN
LTC1502-3.3 TEST CIRCUIT APPLICATIONS INFORMATIONWU UU Regulator Operation The LTC1502-3.3 uses a quadrupler charge pump DC/DC converter to produce a boosted output voltage. The quadrupler charge pump consists of two voltage doubler charge pumps (CP1 and CP2 on the Block Diagram) cascaded in series. CP1 doubles the input voltage V IN and the CP1 output voltage is stored on external capacitor C2. The C2 pin also serves as the input for doubler CP2 whose output is stored on the output capacitor C OUT. Each doubler is controlled by a two-phase clock which is generated in the Timing Control circuit. On phase one of the clock, the flying capacitors C1 and C3 are charged to their respective input voltages. On phase two each charged flying capacitor is stacked on top of the input voltage and discharged through an internal switch onto its respective output. This sequence of charging and discharging the CP1 and CP2 flying capacitors continues at the free running oscillator frequency (500kHz typ) until the output is in regulation. Regulation is achieved by comparing the divided down output voltage to a fixed voltage reference. The charge pump clocks are disabled when the output voltage is above the desired regulation point set by COMP1. When the output has dropped below the lower trip point of COMP1, the charge pump clocks are turned back on until V OUT is boosted back into regulation. Enhanced Start-Up Enhanced start-up capability is provided by the COMP2 circuitry. COMP2 compares the divided down C2 voltage to the input voltage V IN. The COMP2 output disables the output charge pump CP2 whenever the divided C2 voltage is lower than VIN. The CP2 output is thereby forced into a high impedance state until the voltage on C2 has been raised above V IN (the C2 pin should not be loaded for proper start-up). This allows a higher internal gate drive voltage to be generated (from the C2 pin) before the output (VOUT) is connected to a load. Hysteresis in COMP2 forces CP2 to be turned ON and OFF while COUT is charging up to prevent a lockup condition if C2 droops too low during start-up. By the time the output nears the regulation point, the C2 voltage is well above the lower trip point of COMP2 and CP2 will remain enabled. This method of disabling the output charge pump while an internal boosted gate drive supply is developed allows the part to start up at low voltages with a larger output current load than would otherwise be possible. Shutdown Shutdown is implemented using an external pull-down device on the C1 –/SHDN pin. The recommended external pull-down device is an open-drain FET with resistive cur- rent limiting (see Figure 1). The pull-down device must sink up to 300mA and pull down below 0.2V to ensure proper shutdown operation, however, the actual series resistance is not critical. The pull-down device must also go into a Hi- Z state for the LTC1502-3.3 to become active. The timing control circuitry forces the CP1 switches into a high impedance state every 16 clock cycles. The Hi-Z duration is equal to one clock cycle. At the end of the Hi-Z time interval, the voltage on the C1 –/SHDN pin is sampled. If the C1–/SHDN pin has been pulled to a logic low state, the part will go into shutdown mode. When the pull-down device is disabled, an internal pull-up current 1502-3.3 TC 1mF 100W 5VINGND 100pF SWITCH CLOSED FOR SHUTDOWN 1mF 10mF 10mF 10mF IOUT VIN LTC1502-3.3 C1+ C1–/SHDN VOUT C3+ C3–
LTC1502-3.3 APPLICATIONS INFORMATIONWU UU Short-Circuit Protection When the output is shorted to ground, the LTC1502-3.3 will continuously charge the C2 capacitor up to approxi- mately 1.4 times V IN, and then discharge C2 into the shorted output. Since the discharging of C2 into VOUT will bring the C2 voltage below the COMP2 start-up compara- tor trip voltage, the output charge pump will be forced Hi-Z while C2 charges up again. Hence, the internal charge pump gate drive voltage is limited to (1.4)(V IN(MAX)) on the C2 pin, and no continuous current is supplied to VOUT. The resulting output short-circuit current is limited to under 20mA (typ) thereby allowing the LTC1502-3.3 to endure an indefinite output short circuit without damage. When the short is removed, the part will start up, and operate normally. PACKAGE DESCRIPTIONU Dimensions in inches (millimeters) unless otherwise noted. 8-Lead Plastic MSOP (LTC DWG # 05-08-1660) 8-Lead Plastic Small Outline (Narrow 0.150) (LTC DWG # 05-08-1610) Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. MSOP (MS8) 1098 * DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE 0.021 – 0.006 (0.53 – 0.015) 0° – 6° TYP SEATING PLANE 0.007 (0.18) 0.040 – 0.006 (1.02 – 0.15) 0.012 (0.30) REF 0.006 – 0.004 (0.15 – 0.102) 0.034 – 0.004 (0.86 – 0.102) 0.0256 (0.65) BSC 12 3 4 0.193 – 0.006 (4.90 – 0.15) 8 7 6 5 0.118 – 0.004* (3.00 – 0.102) 0.118 – 0.004 (3.00 – 0.102) 0.016 – 0.050 (0.406 – 1.270) 0.010 – 0.020 0°– 8° TYP 0.008 – 0.010 (0.203 – 0.254) SO8 1298 0.053 – 0.069 (1.346 – 1.752) 0.014 – 0.019 (0.355 – 0.483) TYP 0.004 – 0.010 (0.101 – 0.254) 0.050 (1.270) BSC 1 2 3 4 0.150 – 0.157 (3.810 – 3.988) 8 7 6 5 0.189 – 0.197* (4.801 – 5.004) 0.228 – 0.244 (5.791 – 6.197) DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
LTC1502-3.3 15023f LT/TP 0899 4K • PRINTED IN USA ª LINEAR TECHNOLOGY CORPORA TION 1 999 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 l FAX: (408) 434-0507 l www.linear-tech.com TYPICAL APPLICATIONSU PART NUMBER DESCRIPTION COMMENTS LT1307/LT1307B 750mA Single Cell Micropower 600kHz PWM DC/DC Converter 3.3V at 75mA from 1 Cell, MSOP Package LT1308A/LT1308B 2A Single Cell Micropower 600kHz PWM DC/DC Converter 3.3V at 300mA from 1 Cell, SO-8 Package LTC1517-3.3 Micropower Regulated 3.3V Charge Pump DC/DC Converter I OUT = 15mA (VIN ‡ 2.5V) LTC1558/LTC1559 Backup Battery Controller with Programmable Output Uses Single NiCd Cell, 100mW Output (Min) LT1610 Single Cell Micropower 1.7MHz PWM DC/DC Converter 30 mA IQ, MSOP Package LT1611 1.4MHz Inverting Switching Regulator 5V to –5V at 150mA, Low Output Noise, SOT-23 package LT1613 1.4MHz Boost Switching Regulator 5V at 200mA from 3.3V Input, SOT-23 Package LT1615 Micropower Boost Switching Regulator 30 mA IQ, VOUT Up to 34V, SOT-23 Package LTC1682 Low Noise Doubler Charge Pump 60 mVRMS Noise, IOUT Up to 50mA, MSOP RELATED PARTS Single Cell Battery Backup Supply with Autoswitchover and No Reverse Current Single Cell to 3.3V DC/DC Converter with Shutdown 1502-3.3 TA03 SHDN mCONTROLLER 1mF 100W 5VINGND 1mF SINGLE CELL NiCd OR ALKALINE 10mF 10mF 10mF VOUT = 3.3V IOUT = 10mA LTC1502-3.3 C1+ C1–/SHDN VOUT C3+ C3– 1502-3.3 TA04 LT1521-3.3 1mF 3 8 Q1 2N7002 VIN GND 1mF 100W 10mF 150k 1mF 10mF 3.9V VTRIP*
1 CELL
1.1M 10mF VOUT = 3.3V IOUT = 300mA (IOUT = 10mA IN BACKUP MODE) LOGIC LOW = BACKUP MODE LTC1502-3.3 LTC1540 C1+ C1–/SHDN VOUT C3+ C3– TRICKLE CHARGE MAIN SUPPLY 470k *REFERRED TO MAIN SUPPLY