FAN5182 Datasheet, PDF (1/18 Pages) Fairchild Semiconductor – Adjustable Output 1, 2, or 3-Phase Synchronous Buck Controller

May 2005
FAN5182
Adjustable Output 1, 2, or 3-Phase Synchronous Buck
Controller
Features
■ Selectable 1-, 2-, or 3-phase operation at up to 1MHz per
phase
■ ±2% Worst-case differential sensing error over temperature
■ Externally adjustable 0.8V to 5V output from a 12V supply
■ Logic-level PWM outputs for interface to external high-power
drivers
■ Active current balancing between all phases
■ Built-in power-good/crowbar functions
■ Programmable over current protection with adjustable latch-
off delay
Applications
■ Auxiliary supplies
■ DDR memory supplies
■ Point-of-load supplies
Description
The FAN5182 is a highly efficient multi-phase synchronous buck
switching regulator controller optimized for converting a 12V
main supply into a high-current low voltage supply for use in
point-of-load (POL) applications. It uses a multi-loop PWM
architecture to drive the logic-level outputs at a programmable
switching frequency that can be optimized for regulator size and
efficiency. The phase relationship of the output signals can be
programmed to provide 1, 2, or 3-phase operation, allowing for
construction of up to three complementary interleaved buck
switching stages.
The FAN5182 also provides accurate and reliable over-current
protection and adjustable current limiting.
FAN5182 is specified over the commercial temperature range of
0°C to +85°C and is available in a 20-lead QSOP package.
Block Diagram
VCC
1
FAN5182
EN 6
UVLO
SHUTDOWN
& BIAS
GND 14
950mV
–
FB
+
+
650mV
–
PWRGD 5
DELAY
ILIMIT 10
EN
DELAY 7
COMP 4
SOFT
START
RAMPADJ RT
9
8
OSCILLATOR
CURRENT
BALANCING
CIRCUIT
+
CMP
–
+
CMP
–
+
CMP
–
SET
EN
RESET
RESET
1/ 2 / 3-PHASE
DRIVER LOGIC
RESET
20 PWM1
19 PWM2
18 PWM3
CROWBAR
1.05V
–
FB
+
CURRENT
LIMIT
CURRENT
LIMIT
CIRCUIT
17 SW1
16 SW2
15 SW3
12 CSSUM
11 CSREF
13 CSCOMP
3 FB
800 mV
REFERENCE
2
FBRTN
©2005 Fairchild Semiconductor Corporation
1
FAN5182 Rev. 1.0.1
www.fairchildsemi.com