AAT1146

Fast Transient 400mA Step-Down Converter

PRODUCT DATASHEET

1146.2008.06.1.6

9

www .analogictech.com

Functional Description

The AAT1146 is a high performance 400mA 1.4MHz

monolithic step-down converter. It has been designed

with the goal of minimizing external component size and

optimizing efficiency over the complete load range.

Apart from the small bypass input capacitor, only a small

L-C filter is required at the output. Typically, a 4.7μH

inductor and a 4.7μF ceramic capacitor are recommend-

ed (see table of values).

The fixed output version requires only three external

sion can be programmed with external feedback to any

voltage, ranging from 0.6V to the input voltage. An addi-

the external feedback to provide improved transient

response (see Figure 1).

At dropout, the converter duty cycle increases to 100%

and the output voltage tracks the input voltage minus

The input voltage range is 2.7V to 5.5V. The converter

efficiency has been optimized for all load conditions,

ranging from no load to 400mA.

The internal error amplifier and compensation provides

excellent transient response, load, and line regulation.

Soft start eliminates any output voltage overshoot when

the enable or the input voltage is applied.

Functional Block Diagram

EN

LX

Err

.

Amp

Logic

DH

DL

PGND

VIN

OUT

AGND

Voltage

Reference

INPUT

See note

Note: For adjustable version, the internal feedback divider is omitted and the OUT pin is tied directly

to the internal error amplifier.