LTC117- Micropower, Regulated V Charge Pump in a -Pin SOT-23 Package FEATRES ltralow Power: I CC = 6µA Typ Short-Circuit/Thermal Protected V ±% Regulated Output Range: 2.7V to V Output Current: 10mA ( 2.7V) 20mA ( 3V) No Inductors ltrasmall Application Circuit (0.0in 2 ) 800kHz Switching Frequency Available in -Pin SOT-23 APPLICATIONS Cellular Telephones Battery-Operated Equipment Local Power Supplies Handheld Instruments PCMCIA Supplies DESCRIPTION The LTC 117- is a micropower charge pump DC/DC converter that produces a regulated V output. The input voltage range is 2.7V to V. Extremely low operating current (typically 6µA with no load) and low external parts count (one flying capacitor and two small bypass capacitors at and V OT ) make the part ideally suited for small, light load battery-powered applications. The total printed circuit board area of the application circuit shown below is only 0.0in 2. The part operates as a Burst Mode TM switched-capacitor voltage doubler to produce a regulated output. The part has thermal shutdown capability and can survive a continuous short circuit from V OT to GND. The device is available in a -pin SOT-23 package., LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a trademark of Linear Technology Corporation. TYPICAL APPLICATION Typical Output Voltage vs Output Current 2.7V TO V LTC117- GND V OT 1 2 3 6.8µF V OT = V ± % I OT = 10mA ( 2.7V) I OT = 20mA ( 3V) OTPT VOLTAGE (V).2.1.0.9 T A = 2 C C1 = C OT = 6.8µF = 2.7V = 3V = 3.3V 117 TA01.8 0 20 0 60 OTPT CRRENT (ma) 117 TA02 80 1
LTC117- ABSOLTE MAXIMM RATINGS W W W (Note 1) to GND... 0.3V to 6V V OT to GND... 0.3V to 6V V OT Short-Circuit Duration... Indefinite Operating Temperature Range: Commercial... 0 C to 70 C Extended (Note 2)... 0 C to 8 C Storage Temperature Range... 6 C to 10 C Lead Temperature (Soldering, 10 sec)... 300 C PACKAGE/ORDER INFORMATION GND V OT TOP VIEW 1 2 3 T JMAX = 12 C, θ JA = 26 C/ W S PACKAGE -LEAD PLASTIC SOT-23 W ORDER PART NMBER LTC117CS- LTC117ES- S PART MARKING LTCX LTTF Consult factory for Industrial and Military grade parts and for -3 and -3.3 version availability. ELECTRICAL CHARACTERISTICS = 2.7V to V, C1 =, C IN =, C OT = 6.8µF, T MIN to T MAX, unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX NITS Operating Input Voltage 2.7 V V OT Output Voltage 2.7V V, I OT 10mA.8.0.2 V 3V V, I OT 20mA.8.0.2 V I CC Input Supply Current 2.7V V, I OT = 0 6 1 µa V OT Ripple = 3V, I OT = 20mA, C OT = 6.8µF 7 mv P-P f OSC Oscillator Frequency 800 khz t ON V OT Turn-On Time = 3V 1 ms 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. Note 2: Extended grade parts are 100% tested at T A = 2 C. Performance at 0 C and 8 C is assured by design, characterization and correlation with statistical process controls. 2
LTC117- TYPICAL PERFORMANCE CHARACTERISTICS W.1.10 Output Voltage vs Input Voltage I OT = 10mA C OT = 10µF 90 80 Efficiency vs Input Voltage I OT = 10mA T A = 2 C 20 200 Output Ripple vs Input Voltage I OT = 10mA C1 = T A = 2 C OTPT VOLTAGE (V).0.00 T A = 70 C T A = 2 C T A = 0 C EFFICIENCY (%) 70 60 VRIPPLE P-P (mv) 10 100 C OT = C OT = 6.8µF C OT = 10µF.9 0 0 C OT = 22µF.90 2. 3.0 3..0..0 INPT VOLTAGE (V) 0 2. 3.0 3..0..0 INPT VOLTAGE (V) 0 2. 3.0 3..0..0 INPT VOLTAGE (V) 117- G01 117- G02 117- G03 INPT CRRENT (µa) 9 8 7 6 No Load Input Current vs Input Voltage I OT = 0mA T A = 70 C T A = 2 C T A = 0 C EFFICIENCY (%) 90 80 70 60 Efficiency vs Output Current = 3V SHDN = 0V T A = 2 C I OT 0mA to 10mA 10mA/DIV V OT AC COPLED 0mV/DIV Load Transient Response 2. 3.0 3..0..0 INPT VOLTAGE (V) 0 0.01 0.1 1 10 OTPT CRRENT (ma) 100 = 3V 00µs/DIV 117- G06 C OT = 6.8µF 117- G0 117- G0 3
LTC117- SI PLIFIED + PIN FNCTIONS (Pin 1): Charge Pump Input Voltage. May be between 2.7V and V. should be bypassed with a low ESR capacitor as close as possible to the pin for best performance. GND (Pin 2): Ground. Should be tied to a ground plane for best performance. V OT (Pin 3): Regulated Output Voltage. V OT should be bypassed with a low ESR capacitor as close as possible to the pin for best performance. (Pin ): Charge Pump Flying Capacitor Positive Terminal. (Pin ): Charge Pump Flying Capacitor Negative Terminal. W BLOCK DIAGRA W C1 C IN CHARGE PMP 3.7M C OT V OT 800kHz OSC 1.2M THERMAL SHDN 1.2V REF LTC117-117 BD
LTC117- APPLICATIONS INFORMATION Operation W The LTC117- uses a switched-capacitor charge pump to boost to a V ±% 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 V REF ). When the charge pump is enabled, a 2-phase nonoverlapping clock controls the internal charge pump switches. Flying capacitor C1 is charged to on phase one of the clock. On phase two of the clock, C1 is stacked in series with and connected to V OT through an internal switch. This sequence of charging and discharging the flying capacitor occurs at a free running frequency of 800kHz (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 LTC117- to achieve high efficiency at extremely low output loads. Capacitor Selection For best performance, it is recommended that low ESR capacitors be used for both C IN and C OT to reduce noise and ripple. The C IN and C OT capacitors should be either ceramic or tantalum and should be or greater. Ceramic capacitors will provide the smallest size and lowest ESR for a given capacitance. If the input source impedance is very low (< 0.Ω), C IN may not be needed. Ceramic capacitors are recommended for the flying capacitor C1 with values of or 0.22µF. Smaller value flying capacitors may be used in low I OT applications. Output Ripple Normal LTC117- operation produces voltage ripple on the V OT pin. Output voltage ripple is required for the part 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 = 3V under maximum load is 100mV peak-to-peak with a low ESR (< 0.Ω) output capacitor (minimum recommended C OT ). For applications requiring to exceed 3.3V or for applications requiring < 100mV of peak-to-peak ripple, a 6.8µF to 10µF C OT capacitor is recommended. Slight further decreases in output ripple can be achieved by using C OT capacitors larger than 10µF. Short-Circuit/Thermal Protection During short-circuit conditions, the LTC117- will draw between 0mA and 200mA from, 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 1 C. The LTC117- will cycle in and out of thermal shutdown indefinitely without latchup or damage until the V OT short is removed.
LTC117- TYPICAL APPLICATIONS Low Noise Boosted V Supply LTC117- A 0mV/DIV AC COPLED 3.3V TO V GND V OT 1 2 3 70Ω Q2 Q1, Q2: 2N390 70Ω A Q1 117 TA0a B B V OT = V I OT = 1mA ( 3.3V) I OT = 10mA ( 3.6V) V RIPPLE < 2mV P-P V OT 2mV/DIV AC COPLED = 3.3V I OT = 1mA 0µs/DIV 117- TA0b Generating V and a Negative Supply LTC117-2.7V TO V GND V OT 1 2 3 70Ω 8.2k V OT = V ±% I OT = 10mA (2.7V V) I OT = 20mA (3V V) Q1 Q2 * ** 3.3k 117 TA0 V OT = 1.V TO 3.V I OT = 0mA to ma * CENTRAL SEMICONDCTOR CMPSH-3 DAL SCHOTTKY ** OPTIONAL CIRCITRY FOR MAINTAINING V OT WITH LOW V OT LOADS Q1, Q2: 2N390 6
LTC117- PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. S Package -Lead Plastic SOT-23 (LTC DWG # 0-08-1633) 2.80 3.00 (0.110 0.118) (NOTE 3) 2.60 3.00 (0.102 0.118) 1.0 1.7 (0.09 0.069) 1.90 (0.07) REF 0.00 0.1 (0.00 0.006) 0.9 (0.037) REF 0.90 1. (0.03 0.07) 0.10 0.60 (0.00 0.02) REF 0.09 0.20 (0.00 0.008) (NOTE 2) NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DIMENSIONS ARE INCLSIVE OF PLATING 3. DIMENSIONS ARE EXCLSIVE OF MOLD FLASH AND METAL BRR. MOLD FLASH SHALL NOT EXCEED 0.2mm. PACKAGE EIAJ REFERENCE IS SC-7A (EIAJ) 0.3 0.0 0.90 1.30 (0.01 0.020) (0.03 0.01) FIVE PLACES (NOTE 2) S SOT-23 0797 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
LTC117- TYPICAL APPLICATION 3.3V to 1.9V, 6A Power Supply C1 YV CERAMIC C2 YV CERAMIC 10µF 1 2 LTC117-3 V C D1 BAT C3 0.22µF C6 TO C9* 330µF 6.3V C10 LTC130CS 1 16 G1 G2 2 1 PV CC1 PV CC2 3 1 PGND V CC C 13 GND I FB SENSE 12 I MAX 6 11 R FB FREQSET 7 SENSE + 10.2k COMP 8 9 ON OFF SHDN SS + R1 100Ω 3.3V + C12 R3 1k R2 2k C13 390pF Q1 Si10 Q2 Si10 C11 C1 0.012µF L1 2.µH, 8A SMIDA CDRH127-2R D2 MBRS120 C1 10µF 10V C16 0.018µF R.99K 1% R6 10K 1% + V OT 1.9V 6A C17 TO C21 * 330µF 6.3V 117 TA03 *AVX TPS TANTALM RELATED PARTS PART NMBER DESCRIPTION COMMENTS LTC11-X Step-p/Step-Down Switched-Capacitor DC/DC Converter with 3.3V or V Output p to 0mA Low Battery Comparator LTC11 Series Step-p/Step-Down Switched-Capacitor DC/DC Converter with Reset Fixed or Adjustable Output p to 0mA LTC116 Micropower Regulated V Charge Pump DC/DC Converter 20mA for 2V, 0mA for 3V LTC122 Micropower Regulated V Charge Pump DC/DC Converter Same as LTC117- with Shutdown, Available in MSOP 8 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 903-717 (08) 32-1900 FAX: (08) 3-007 TELEX: 99-3977 www.linear-tech.com 117fs, sn117a LT/TP 0298 K PRINTED IN SA LINEAR TECHNOLOGY CORPORATION 1997