LTC1517-3.3 Micropower, Regulated 3.3V Charge Pump in a 5-Pin SOT-23 Package U DESCRIPTION FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ Ultralow Power: ICC = 6µA Typ Short-Circuit/Thermal Protected 3.3V ±4% Regulated Output VIN Range: 2V to 4.4V Output Current: 8mA (VIN ≥ 2V) 15mA (VIN ≥ 2.5V) No Inductors Ultrasmall Application Circuit (0.045in2) 700kHz Switching Frequency Available in 5-Pin SOT-23 The LTC®1517-3.3 is a micropower charge pump DC/DC converter that produces a regulated 3.3V output. The input voltage range is 2V to 4.4V, allowing a single cell lithium battery to produce a regulated 3.3V output over the entire life of the battery. Extremely low operating current (typically 6µA with no load) and low external parts count (one 0.1µF flying capacitor and two small bypass capacitors at VIN and VOUT) make the part ideally suited for small, light load batterypowered applications. The total printed circuit board area of the application circuit shown below is only 0.045in2. The part operates as a Burst ModeTM switched-capacitor voltage doubler to produce a regulated output. The part has thermal shutdown capability and can survive a continuous short circuit from VOUT to GND. The device is available in a 5-pin SOT-23 package. U APPLICATIONS ■ ■ ■ ■ Cellular Telephones Battery-Operated Equipment Local Power Supplies Handheld Instruments PCMCIA Supplies , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a trademark of Linear Technology Corporation. U ■ TYPICAL APPLICATION Typical Output Voltage vs Output Current 3.40 0.1µF 4 C1 + LTC1517-3.3 VIN 2V TO 4.4V 3.3µF VIN GND VOUT 1 2 3 6.8µF VOUT = 3.3V ± 4% IOUT = 8mA (VIN ≥ 2V) IOUT = 15mA (VIN ≥ 2.5V) OUTPUT VOLTAGE (V) 5 C1 – TA = 25°C C1 = 0.1µF COUT = 6.8µF 3.35 3.30 VIN = 2V VIN = 2.5V 3.25 1517-3.3 TA01 3.20 0 20 30 10 OUTPUT CURRENT (mA) 40 1517 G05 1 LTC1517-3.3 U W U U W W W ABSOLUTE MAXIMUM RATINGS PACKAGE/ORDER INFORMATION (Note 1) VIN to GND ...................................................– 0.3V to 6V VOUT to GND ................................................– 0.3V to 6V VOUT Short-Circuit Duration ............................. Indefinite Operating Temperature Range: Commercial (Note 2) .............................. 0°C to 70°C Storage Temperature Range ................. – 65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C ORDER PART NUMBER TOP VIEW VIN 1 GND 2 VOUT 3 5 C1 – 4 C1 + LTC1517CS5-3.3 S5 PACKAGE 5-LEAD PLASTIC SOT-23 S5 PART MARKING LTEF TJMAX = 125°C, θJA = 256°C/ W Consult factory for Industrial and Military grade parts. ELECTRICAL CHARACTERISTICS VIN = 2V to 4.4V, C1 = 0.1µF, CIN = 3.3µF, COUT = 6.8µF, TMIN to TMAX, unless otherwise noted. SYMBOL PARAMETER VIN Operating Input Voltage VOUT Output Voltage ICC CONDITIONS MIN ● 2.0 2V ≤ VIN ≤ 4.4V, IOUT ≤ 8mA 2.5V ≤ VIN ≤ 4.4V, IOUT ≤ 15mA ● ● 3.17 3.17 Input Supply Current 2V ≤ VIN ≤ 4.4V, IOUT = 0 ● VOUT Ripple VIN = 2.5V, IOUT = 15mA, COUT = 6.8µF TYP MAX UNITS 4.4 V 3.3 3.3 3.43 3.43 V V 6 15 µA 50 mVP-P fOSC Oscillator Frequency 700 kHz tON VOUT Turn-On Time VIN = 2.5V 1 ms ISC Output Short-Circuit Current VIN = 3V 60 mA The ● denotes specifications that apply over the full operating temperature range. Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired. 2 Note 2: Commercial grade parts are designed to operate over the temperature range of – 40°C to 85°C but are neither tested nor guaranteed beyond 0°C to 70°C. LTC1517-3.3 U W TYPICAL PERFORMANCE CHARACTERISTICS Output Voltage vs Input Voltage 100 200 IOUT = 8mA COUT = 6.8µF IOUT = 8mA TA = 25°C 80 TA = 70°C 3.30 TA = 0°C TA = 25°C 60 3.25 IOUT = 8mA C1 = 0.1µF CIN = 3.3µF TA = 25°C 150 VRIPPLE P-P (mV) 3.35 EFFICIENCY (%) OUTPUT VOLTAGE (V) Output Ripple vs Input Voltage Efficiency vs Input Voltage 3.40 40 COUT = 3.3µF 100 COUT = 6.8µF 50 COUT = 10µF 3.20 2.0 2.5 3.5 4.0 3.0 INPUT VOLTAGE (V) 20 2.0 4.5 2.5 3.5 4.0 3.0 INPUT VOLTAGE (V) 1517 G01 2.5 3.5 4.0 3.0 INPUT VOLTAGE (V) 1517 G02 No Load Input Current vs Input Voltage 4.5 1517 G03 Typical Efficiency vs Output Current 10 Load Transient Response 100 IOUT = 0mA TA = 25°C C1 = 0.1µF COUT = 6.8µF 80 EFFICIENCY (%) 8 TA = 70°C 6 TA = 25°C TA = 0°C VIN = 2V IOUT 0mA to 10mA 5mA/DIV VIN = 2.5V 60 VOUT AC COUPLED 50mV/DIV 40 4 20 2.5 3.5 4.0 3.0 INPUT VOLTAGE (V) VIN = 2.5V COUT = 6.8µF 0 0.001 4.5 0.01 1 10 0.1 OUTPUT CURRENT (mA) 1517 G04 500µs/DIV 1517 G06 100 1517 TA02 Typical Output Current vs Temperature VOUT Short-Circuit Current vs Input Voltage 200 50 VOUT = 3.3V C1 = 0.1µF VOUT SHORT-CIRCUIT CURRENT (mA) 2 2.0 40 OUTPUT CURRENT (mA) INPUT CURRENT (µA) 0 2.0 4.5 VIN = 2.7V 30 VIN = 2.5V 20 VIN = 2V 10 0 –50 –25 0 25 50 TEMPERATURE (°C) 75 100 1517 G09 TA = 25°C C1 = 0.1µF 160 120 80 40 0 2.0 2.5 3.5 4.0 3.0 INPUT VOLTAGE (V) 4.5 1517 G10 3 LTC1517-3.3 U W TYPICAL PERFORMANCE CHARACTERISTICS Oscillator Frequency vs Input Voltage Oscillator Frequency vs Temperature 900 900 VIN = 2.5V OSCILLATOR FREQUENCY (kHz) OSCILLATOR FREQUENCY (kHz) TA = 25°C 800 700 600 500 2.0 2.5 3.5 4.0 3.0 INPUT VOLTAGE (V) 800 700 600 500 400 –50 4.5 –25 0 25 50 TEMPERATURE (°C) 75 100 1517 G08 1517 G07 U U U PIN FUNCTIONS VIN (Pin 1): Charge Pump Input Voltage. May be between 2V and 4.4V. VIN should be bypassed with a ≥ 3.3µF low ESR capacitor as close as possible to the pin for best performance. C1 + (Pin 4): Charge Pump Flying Capacitor Positive Terminal. C1 – (Pin 5): Charge Pump Flying Capacitor Negative Terminal. GND (Pin 2): Ground. Should be tied to a ground plane for best performance. VOUT (Pin 3): Regulated Output Voltage. VOUT should be bypassed with a ≥3.3µF low ESR capacitor as close as possible to the pin for best performance. W W SI PLIFIED BLOCK DIAGRA C1 0.1µF C1 – VIN C1 + VOUT CHARGE PUMP CIN 2.05M COUT + 700kHz OSC – THERMAL SHDN 1.25M 1.25V REF 1517-3.3 BD 4 LTC1517-3.3 U W U U APPLICATIONS INFORMATION Operation Output Ripple The LTC1517-3.3 uses a switched-capacitor charge pump to boost VIN to a 3.3V ±4% regulated output. The part achieves regulation by sensing the output voltage through an internal resistor divider and enabling the charge pump when the divided output droops below the comparator’s lower trip point (set by VREF). When the charge pump is enabled, a 2-phase nonoverlapping clock controls the internal charge pump switches. Flying capacitor C1 is charged to VIN on phase one of the clock. On phase two of the clock, C1 is stacked in series with VIN and connected to VOUT through an internal switch. This sequence of charging and discharging the flying capacitor occurs at a free running frequency of 700kHz (typ) and continues until the divided output voltage reaches the upper trip point of the comparator. Once the output is back in regulation, the charge pump is disabled. This method of bursting the charge pump on and off enables the LTC1517-3.3 to achieve high efficiency at extremely low output loads. Normal LTC1517-3.3 operation produces voltage ripple on the VOUT pin. Output voltage ripple is required for the parts to regulate. Low frequency ripple exists due to the hysteresis in the sense comparator and propagation delays in the charge pump enable/disable circuits. High frequency ripple is also present mainly from the ESR (equivalent series resistance) in the output capacitor. Typical output ripple with VIN = 2.5V under maximum load is 75mV peak-to-peak with a low ESR 3.3µF output capacitor (minimum recommended COUT). For applications requiring VIN to exceed 3.3V or for applications requiring less than 75mV of peak-to-peak ripple, a 6.8µF to 10µF COUT capacitor is recommended. Slight further decreases in output ripple can be achieved by using COUT capacitors larger than 10µF. Capacitor Selection For best performance, it is recommended that low ESR capacitors be used for both CIN and COUT to reduce noise and ripple. The CIN and COUT capacitors should be either ceramic or tantalum and should be 3.3µF or greater. Ceramic capacitors will provide the smallest size for a given capacitance. If the input source impedance is very low (< 0.5Ω), CIN may not be needed. Ceramic capacitors are recommended for the flying capacitor C1 with values of 0.1µF or 0.22µF. Smaller value flying capacitors may be used in low IOUT applications. Short-Circuit/Thermal Protection During short-circuit conditions, the LTC1517-3.3 will draw between 20mA and 150mA from VIN, causing a rise in junction temperature. On-chip thermal shutdown circuitry disables the charge pump once the junction temperature exceeds approximately 160°C. The charge pump is reenabled once the junction temperature drops to approximately 145°C. The LTC1517-3.3 will cycle in and out of thermal shutdown indefinitely without latchup or damage until the VOUT short is removed. 5 LTC1517-3.3 U TYPICAL APPLICATIONS Low Noise Boosted 3.3V Supply 0.1µF 5 4 C1 – C1 + LTC1517-3.3 VIN 2.7V TO 4.4V VIN GND VOUT 1 2 3 50mV/DIV AC COUPLED B VOUT 2mV/DIV AC COUPLED A 3.3µF 470Ω 470Ω A 3.3µF Q1 B 3.3µF Q2 VOUT = 3.3V IOUT = 8mA 1µF Q1, Q2: 2N3904 VIN = 2.7V IOUT = 5mA VRIPPLE = 2mVP-P 1517 TA04a 10µs/DIV Generating 3.3V and a Negative Supply 0.1µF 5 4 C1 – C1 + LTC1517-3.3 VIN 2V TO 4.4V VIN GND VOUT 1 2 3 3.3µF 3.3µF 470Ω Q1 21.5k Q2 10k 0.1µF ** 1517 TA05 3.3µF * *CENTRAL SEMICONDUCTOR CMPSH-35 DUAL SCHOTTKY **OPTIONAL CIRCUITRY FOR MAINTAINING – VOUT WITH LOW VOUT LOADS Q1, Q2: 2N3904 6 VOUT = 3.3V ± 4% IOUT = 5mA (2V ≤ VIN ≤ 4.4V) IOUT = 10mA (2.5V ≤ VIN ≤ 4.4V) – VOUT = –0.8V TO – 3V – IOUT = 0mA to 5mA 1517 TA04b LTC1517-3.3 U PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. S5 Package 5-Lead Plastic SOT-23 (LTC DWG # 05-08-1633) 2.80 – 3.00 (0.110 – 0.118) (NOTE 3) 2.60 – 3.00 (0.102 – 0.118) 1.50 – 1.75 (0.059 – 0.069) 0.10 – 0.60 (0.004 – 0.024) REF 0.09 – 0.20 (0.004 – 0.008) (NOTE 2) 1.90 (0.074) REF 0.00 – 0.15 (0.00 – 0.006) 0.95 (0.037) REF 0.90 – 1.45 (0.035 – 0.057) 0.35 – 0.50 0.90 – 1.30 (0.014 – 0.020) (0.035 – 0.051) FIVE PLACES (NOTE 2) S5 SOT-23 0797 NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DIMENSIONS ARE INCLUSIVE OF PLATING 3. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR 4. MOLD FLASH SHALL NOT EXCEED 0.254mm 5. PACKAGE EIAJ REFERENCE IS SC-74A (EIAJ) 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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 7 LTC1517-3.3 U TYPICAL APPLICATION Low Power Battery Backup Supply with Autoswitchover and No Reverse Current MAIN SUPPLY 5V 3 1µF VOUT = 3.3V, IOUT = 300mA (IOUT = 8mA IN BACKUP MODE) 1 LT1521-3.3 1.5µF 2 BAT54 0.1µF 75k TRICKLE CHARGE AND LTC1517-3.3 IDD 5 1 2-CELL NiCd 4 LTC1517-3.3 3.3µF 3.3µF 2 7 1.1M 3.9VTRIP 470k SILICONIX Si2301DS 3 3 + 4 – 8 LOGIC LOW = BACKUP MODE 5 6 1517-3.3 TA03 LTC1540 2 1 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC1514-X Step-Up/Step-Down Switched-Capacitor DC/DC Converter with Low Battery Comparator 3.3V or 5V Output up to 50mA LTC1515 Step-Up/Step-Down Switched-Capacitor DC/DC Converter with POR Fixed or Adjustable Output up to 50mA LTC1516 Micropower Regulated 5V Charge Pump DC/DC Converter 20mA for VIN ≥ 2V, 50mA for VIN ≥ 3V LTC1517-5 Micropower Regulated 5V Charge Pump in a 5-Pin SOT-23 Package IOUT up to 20mA LTC1522 Micropower Regulated 5V Charge Pump DC/DC Converter Same as LTC1517-5 with Shutdown 8 Linear Technology Corporation 15173f LT/TP 0998 4K • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com LINEAR TECHNOLOGY CORPORATION 1998