PRODUCT DATASHEET
AAT1189
TM
SwitchReg
High Voltage Step-Down Regulator
Functional Block Diagram
VINT
Reg.
OT
IN
VL
OSC
Comp.
Comp.
FB
BST
Error
Error
Amp
Amp
COMP
EN
Logic
LX
Control
Logic
20Ω
Voltage
Ref
RS
Comp
OS
VOCP
= 0.1V
GND
sensed through the output inductor DC winding resis-
tance (DCR). An external resistor and capacitor network
adjusts the current limit according to the DCR of the
inductor and the desired output current limit. Frequency
reduction limits the over-current stress during overload
and short-circuit events. The operating frequency returns
to the nominal setting when over-current conditions are
removed.
Functional Description
The AAT1189 is a high voltage step-down (Buck) regula-
tor with input voltage range from 6.0V to 24.0V, provid-
ing high output current in a small package. The output
voltage is user-programmable from 1.5V to approxi-
mately 85% of VIN voltage. The device is optimized for
low-cost 12V adapter inputs.
The device utilizes voltage mode control configured for
optimum performance across the entire output voltage
and load range.
The AAT1189 is available in the Pb-free 16-pin TDFN34
package with rated operating temperature range of
-40°C to 85°C. The TDFN34-16's exposed paddle (EP)
can be soldered to the PCB plane(s) for maximum ther-
mal performance.
The controller includes integrated over-current, soft-
start and over-temperature protection. Over-current is
w w w . a n a l o g i c t e c h . c o m
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1189.2008.06.1.0
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