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ADP3171
Synchronous Buck Controller
with Dual Linear Regulator Controllers
FUNCTIONAL BLOCK DIAGRAM
OSCILLATOR
PWM
LOGIC
SET
RESET
CROWBAR
1.8V
LRFB2
LRDRV2
REFERENCE REF
1GND
DAC +20%
DAC –20%
CMP
g
m
UVLO
AND BIAS
DRVH
VCC
COMP
DRVL
PWRGD
CS–
CS+
FB
CT
ADP3171
5
7
1.5V
LRFB1
LRDRV1
3
4
8
1.2V
FEATURES
Fixed 1.2 V N-Channel Synchronous Buck Driver
Two On-Board Linear Regulator Controllers
Total Accuracy ±1% over Temperature
High Efficiency Current-Mode Operation
Short Circuit Protection
Power Good Output
Overvoltage Protection Crowbar Protects Switching
Output with No Additional External Components
APPLICATIONS
Auxiliary System Supplies for Desktop
Computer Systems
General-Purpose Low Voltage Supplies
GENERAL DESCRIPTION
The ADP3171 is a highly efficient output synchronous buck
switching regulator controller optimized for converting a 5 V
main supply into the auxiliary supply voltages required by
processors and chipsets. The ADP3171 provides a fixed
output voltage of 1.2 V at up to 15 A, depending on the
power ratings of the external MOSFETs and inductor. The
ADP3171 uses a current-mode, constant off time architecture to
drive two N-channel MOSFETs at a programmable switching
frequency that can be optimized for regulator size and efficiency.
The ADP3171 provides accurate and reliable short circuit
protection and adjustable current limiting. It also includes an
integrated overvoltage crowbar function to protect the load in
case the output voltage exceeds the nominal programmed
voltage by more than 20%.
The ADP3171 contains two fixed output voltage linear regulator
controllers that are designed to drive external N-channel
MOSFETs. These linear regulators are used to generate the
auxiliary voltages required in most motherboard designs and have
been designed to provide a high bandwidth load-transient response.
The ADP3171 is specified over the commercial temperature
range of 0°C to 70°C and is available in a 14-lead SOIC package.