AAT1185 Datasheet, PDF (8/16 Pages) Skyworks Solutions Inc. – High Voltage Step-Down Controller

Functional Block Diagram
DATA SHEET
AAT1185
High Voltage Step-Down Controller
VL
FB
COMP
EN
EN
VINT
Reg.
OT
OSC
Error
Amp
CCoommpp..
Control
Logic
Voltage
Ref
Logic
Comp
VOCP
= 0.1V
IN
BST
DH
LX
DL
PGND
RS
OS
Applications Information
The AAT1185 is a single output step-down (Buck) regu-
lator controller with an input range of 6V to 24V. The
output range is adjustable from 0.8V to 5.5V.
The device provides high and low-side pins to drive
external n-channel MOSFETs; allowing fully synchronous
operation for maximum efficiency and performance.
Alternatively, the low-side MOSFET may be replaced with
a Schottky rectifier and the DL pin left open. Both high
and low-side drive pins are compatible with a wide range
of external MOSFETs making the device the ideal control
solution for low power and high power configurations.
Voltage mode control allows for optimum performance
across the entire output voltage and load range. 490kHz
fixed switching frequency allows wide range of L/C filter-
ing components, achieving smallest size and maximum
efficiency. External compensation allows the designer to
optimize the transient response components.
The controller includes programmable over-current, inte-
grated soft-start and over-temperature protection.
The AAT1185 is available in the Pb-free, 14-pin TSOPJW
package. The rated operating temperature range is
-40°C to 85°C.
Regulator Output Capacitor Selection
Two 47μF ceramic output capacitors are required to filter
the inductor current ripple and supply the load transient
current for I_OUT = 10A. The 1210 package with 10V
minimum voltage rating is recommended for the output
capacitors to maintain a minimum capacitance drop with
DC bias.
Output Inductor Selection
The step-down converter utilizes constant frequency
(PWM-mode) voltage mode control. A 3.9μH to 4.7μH
inductor value with appropriate DCR is selected to main-
tain the desired output current ripple and minimize the
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
8
202001A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 31, 2012