AAT1147 AAT, AAT1147 Datasheet - Page 8

• Manufacturer Part Number: AAT1147
• Description: Step-Down Converter
• Manufacturer: AAT

Functional Block Diagram
Functional Description
The AAT1147 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 at heavy
load. 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 recommended (see table of values).
Only three external power components (C
and L) are required. Output voltage is programmed
with external resistors and ranges from 0.6V to the
input voltage. An additional feed-forward capacitor
can also be added to the external feedback to pro-
8
EN
Reference
Voltage
INPUT
OUT
Amp
Err
.
IN
, C
High Efficiency, Low Noise, Fast Transient
OUT
,
vide improved transient response (see Figure 1).
At dropout, the converter duty cycle increases to
100% and the output voltage tracks the input volt-
age minus the R
side MOSFET.
The input voltage range is 2.7V to 5.5V. The con-
verter efficiency has been optimized for heavy load
conditions up to 400mA.
The internal error amplifier and compensation pro-
vide excellent transient response, load, and line
regulation. Soft start eliminates any output voltage
overshoot when the enable or the input voltage is
applied.
Logic
400mA Step-Down Converter
DH
DL
DS(ON)
VIN
drop of the P-channel high-
LX
PGND
AGND
1147.2006.05.1.0