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GENERAL DESCRIPTION

The ML4950 is a low power boost regulator designed for

low voltage DC to DC conversion in single cell battery

powered systems. The maximum switching frequency can

exceed 100kHz, allowing the use of small, low cost

inductors.

The combination of integrated synchronous rectification,

variable frequency operation, and low supply current

make the ML4950 ideal for single cell applications. The

ML4950 is capable of start-up with input voltages as low

as 1V, and the output voltage can be set anywhere

between 2V and 3V.

An integrated synchronous rectifier eliminates the need for

an external Schottky diode and provides a lower forward

voltage drop, resulting in higher conversion efficiency. In

addition, low quiescent battery current and variable

frequency operation result in high efficiency even at light

loads. The ML4950 requires a minimum number of

external components and is capable of achieving

conversion efficiencies in excess of 90%.

The circuit also contains a RESET output which goes low

when the IC can no longer function due to low input

voltage, or when the DETECT input drops below 200mV.

*Some Packages Are Obsolete

FEATURES

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Guaranteed full load start-up and operation at 1V input

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Pulse Frequency Modulation (PFM) and internal

synchronous rectification for high efficiency

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Minimum external components

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Low ON resistance internal switching FETs

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Micropower operation

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Adjustable output voltage (2V to 3V)

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Low battery detect

BLOCK DIAGRAM

July 2000

ML4950

*

Adjustable Output, Low Current

Single Cell Boost Regulator with Detect

VREF

VOUT

VL

5

SENSE

3

VIN

1

DETECT

4

PWR

GND

8

6

RESET

VREF

–

+

+

–

S

R

Q

Q

5µs

ONE SHOT

START-UP

REFERENCE

GND

2

VREF

+

–

COMP

7

FEATURING

Extended Commercial

Temperature

Range

-20˚C to 70˚C

for Portable

Handheld

Equipment