AAT1162_08 Datasheet, PDF (9/18 Pages) Advanced Analogic Technologies – 12V, 1.5A Step-Down DC/DC Converter

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Functional Block Diagram
PRODUCT DATASHEET
AAT1162
12V, 1.5A Step-Down DC/DC Converter
LDO
AIN
Note 1
FB
Current
Sense Amp ₊
LDO
-
+
Error
Amp -
+
-
Current
Mode
Comparator
Control
Logic
Reference
EN
IN
LX
PGND
AGND
DGND
COMP
Note 1: For fixed output voltage versions, FB is connecte. d to the
error amplifier through the resistive voltage divider shown.
Functional Description
The AAT1162 is a current-mode step-down DC/DC con-
verter that operates over a wide 4V to 13.2V input volt-
age range and is capable of supplying up to 1.5A to the
load with the output voltage regulated as low as 0.6V.
Both the P-channel power switch and N-channel syn-
chronous rectifier are internal, reducing the number of
external components required. The output voltage is
adjusted by an external resistor divider; fixed output
voltage versions are available upon request. The regula-
tion system is externally compensated, allowing the cir-
cuit to be optimized for each application. The AAT1162
includes cycle-by-cycle current limiting, frequency fold-
back for improved short-circuit performance, and ther-
mal overload protection to prevent damage in the event
of an external fault condition.
Control Loop
The AAT1162 regulates the output voltage using con-
stant frequency current mode control. The AAT1162
monitors current through the high-side P-channel
MOSFET and uses that signal to regulate the output volt-
age. This provides improved transient response and
eases compensation. Internal slope compensation is
included to ensure the current “inside loop” stability.
1162.2008.01.1.3
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