REV.A
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a
ADM1052
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700 World Wide Web Site: http://www.analog.com
Fax: 781/326-8703 © Analog Devices, Inc., 2001
Precision Dual Voltage
Regulator Controller
FEATURES
Two Independent Controllers on One Chip
Two 2.525 V Outputs
Shutdown Inputs to Control Each Channel
H115502.5% Accuracy Over Line, Load, and Temperature
Low Quiescent Current
Low Shutdown Current
Works with External N-Channel MOSFETs for Low Cost
“Hiccup Mode” Fault Protection
No External Voltage or Current Setting Resistors
Small, 8-Lead SO Package
APPLICATIONS
Desktop Computers
Servers
Workstations
GENERAL DESCRIPTION
The ADM1052 is a dual, precision, voltage regulator controller
intended for power rail generation and active bus termination
on personal computer motherboards. It contains a precision
1.2 V bandgap reference and two channels consisting of con-
trol amplifiers driving external power devices. Each channel has a
shutdown input to turn off amplifier output and “Hiccup Mode”
protection circuitry for the external power device.
The ADM1052 operates from a 12 V supply. This gives suffi-
cient headroom for the amplifiers to drive external N-channel
MOSFETs, operating as source-followers, as the external series
pass devices. This has the advantage that N-channel devices are
cheaper than P-channel devices of similar performance, and the
circuit is easier to stabilize than one using P-channel devices in
a common-source configuration.
FUNCTIONAL BLOCK DIAGRAM
SHDN1
V
CC
BANDGAP
REFERENCE
SHUTDOWN
CONTROL
HICCUP
COMPARATOR
100H9262F
2 H11547 100H9262F
3.3V
V
OUT1
CONTROL
AMPLIFIER
FORCE 1
SENSE 1
V
CC
50H9262A
ADM1052
3.3V
V
OUT2
FORCE 2
SENSE 2
SHDN2
V
CC
SHUTDOWN
CONTROL
HICCUP
COMPARATOR
CONTROL
AMPLIFIER
50H9262A
GND
CLOCK
OSCILLATOR
POWER-ON
RESET
CLK/DELAY
GENERATOR
V
CC
100H9262F
2 H11547 100H9262F