LM2612

400mA Sub-miniature, Programmable, Step-Down DC-DC

Converter for Ultra Low-Voltage Circuits

General Description

The LM2612 step-down DC-DC converter is optimized for

powering ultra-low voltage circuits from a single Lithium-Ion

cell. It provides up to 400mA (300mA for B grade), over an

input voltage range of 2.8V to 5.5V. Pin programmable out-

put voltages of 1.05V, 1.3V, 1.5V or 1.8V allow adjustment

for MPU voltage options without board redesign or external

feedback resistors.

The device has three pin-selectable modes for maximizing

battery life in mobile phones and similar portable applica-

tions. Low-noise PWM mode offers 600kHz fixed-frequency

operation to reduce interference in RF and data acquisition

applications during full-power operation. In PWM mode, in-

ternal synchronous rectification provides high efficiency

(91% typ. at 1.8V

the switching frequency in a range of 500kHz to 1MHz to

avoid noise from intermodulation with system frequencies.

Low-current hysteretic PFM mode reduces quiescent current

to 150 µA (typ.) during system standby. Shutdown mode

turns the device off and reduces battery consumption to

0.1µA (typ.). Additional features include soft start and current

overload protection.

The LM2612 is available in a 10 pin micro SMD packge. This

package uses National’s wafer level chip-scale micro SMD

technology and offers the smallest possible size. Only three

small external surface-mount components, an inductor and

two ceramic capacitors are required.

Key Specifications

n

Operates from a single LiION cell (2.8V to 5.5V)

n

Pin programmable output voltage (1.05V, 1.3V, 1.5V and

1.8V)

n

400mA maximum load capability (300mA for B grade)

2% PWM mode DC output voltage precision

n

2mV typ PWM mode output voltage ripple

n

150 µA typ PFM mode quiescent current

n

0.1µA typ shutdown mode current

n

Internal synchronous rectification for high PWM mode

efficiency (91% at 2.8V

n

600kHz PWM mode switching frequency

n

SYNC input for PWM mode frequency synchronization

from 500kHz to 1MHz

Features

n

Sub-miniature 10-pin micro SMD package

n

Only three tiny surface-mount external components

required

n

Uses small ceramic capacitors.

n

Internal soft start

n

Current overload protection

n

No external compensation required

Applications

n

Mobile Phones

n

Hand-Held Radios

n

Battery Powered Devices

Typical Application Circuit

20007102

May 2002

© 2002 National Semiconductor Corporation

DS200071

www.national.com