LINEAR TECHNOLOGY - 1 LTC1751 LTC1751-3.3 LTC1751-5 Data Sheet Owner's Manual

LTC1751/LTC1751-3.3/LTC1751-5 Micropower, Regulated

Charge Pump DC/DC Converters

FEATURES DESCRIPTIO 5V Output Current: 100m A (VIN ≥ 3V) The LTC®1751 family are micropower charge pump DC/ 3.3V Output Current: 80m A (VIN ≥ 2.5V) DC converters that produce a regulated output voltage at Ultralow Power: 20µA Quiescent Current up to 100m A. The input voltage range is 2V to 5.5V. Regulated Output Voltage: 3.3V ±4%, 5V ±4%, ADJ Extremely low operating current (20µA typical with no No Inductors load) and low external parts count (one flying capacitor Short-Circuit/Thermal Protection and two small bypass capacitors at VIN and VOUT) make VIN Range: 2V to 5.5V them ideally suited for small, battery-powered applica- 800k Hz Switching Frequency tions. Very Low Shutdown Current: <2µA

The LTC1751 family operate as Burst Mode TM switched

Shutdown Disconnects Load from VIN

capacitor voltage doublers to achieve ultralow quiescent

Power Good/Undervoltage Output

current. They have thermal shutdown capability and can

Adjustable Soft-Start Time

survive a continuous short circuit from VOUT to GND. The

Available in an 8-Pin MSOP Package

PGOOD pin on the LTC1751-3.3 and LTC1751-5 indicates when the output voltage has reached its final value and if APPLICATIO S the output has an undervoltage fault condition. The FB pin OU TP UT OL TA GE (V of the adjustable LTC1751 can be used to program the

Li-Ion Battery Backup Supplies

desired output voltage or current. An optional soft-start

Local 3V and 5V Conversion

capacitor may be used at the SS pin to prevent excessive

Smart Card Readers

inrush current during start-up.

PCMCIA Local 5V Supplies

The LTC1751 family is available in an 8-pin MSOP

White LED Backlighting

package. , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a trademark of Linear Technology Corporation.

TYPICAL APPLICATIO

Output Voltage vs Input Voltage 5.2 IOUT = 50m A Regulated 5V Output from a 2.7V to 5.5V Input CFLY = 1µF COUT = 10µF 5.1

2.7V VIN VOUT TA = 85°C

TO 5.5V C2 R1 C1

IOUT ≤ 100m A, VIN ≥ 3V TA = 25°C

OFF ON SHDN PGOOD PGOOD IOUT ≤ 50m A, VIN ≥ 2.7V

LTC1751-5

SS C+ TA = –40°C

GND C–

1751 TA01

CFLY = MURATA GRM39X5R105K6.3AJ

C1, C2 = MURATA GRM40X5R106K6.3AJ 4.8 2.5 3.0 3.5 4.0 4.5 5.0 5.5

INPUT VOLTAGE (V)

1751 TA02