AAT1123IJS-1.2-T1 Advanced Analog Technology, Inc., AAT1123IJS-1.2-T1 Datasheet - Page 8

• Manufacturer Part Number: AAT1123IJS-1.2-T1
• Description: 1MHz Step-Down Converter
• Manufacturer: Advanced Analog Technology, Inc.

Functional Block Diagram
Functional Description
The AAT1123 is a high performance 600mA 1MHz
monolithic step-down converter. It has been
designed with the goal of minimizing external com-
ponent size and optimizing efficiency over the com-
plete load range. Apart from the small bypass input
capacitor, only a small L-C filter is required at the out-
put. Typically, a 4.7µH inductor and a 22µF ceramic
capacitor are recommended (see Table of Values).
The fixed output version requires only three external
power components (C
adjustable version can be programmed with external
feedback to any voltage, ranging from 0.6V to the
input voltage. An additional feed-forward capacitor
8
EN
Note: For adjustable version, the internal feedback divider is omitted and the FB pin is tied directly
to the internal error amplifier.
IN
, C
Reference
Voltage
INPUT
OUT
, and L). The
Amp
See note
Err
.
OUT
can also be added to the external feedback to pro-
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 all load
conditions, ranging from no load to heavy load.
The internal error amplifier and compensation pro-
vides excellent transient response, load, and line
regulation. Soft start eliminates any output voltage
overshoot when the enable or the input voltage is
applied.
Logic
1MHz Step-Down Converter
DH
DL
DSON
VIN
drop of the P-channel high-
LX
PGND
AGND
AAT1123
1123.2007.02.1.6