Preliminary
Features
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HT82P604B
DC-DC Converter
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Operating voltage: 5V~12V
Drives two N-Channel MOSFETs
Simple single-loop control design
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Voltage-mode PWM control
Fast transient response
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High-bandwidth error amplifier
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Full 0% to 100% duty ratio
Excellent output voltage regulation
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鹵1%
over line voltage and temperature
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5 bit digital-to-analog output voltage selection
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Wide range
-1.3V
to 3.5V
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0.1V binary steps from 2.1V to 3.5V
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0.05V binary steps from 1.3V to 2.05V
Power-good output voltage monitor
Over-voltage and over-current sensing ele-
ment, uses MOSFET壟s r
DS (ON)
Small converter size
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Constant frequency operation
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200kHz free-running oscillator program-
mable from 50kHz to over 1MHz
Applications
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Power supply for Pentium
TM
, Pentium
TM
Pro, PowerPC
TM
and Alpha
TM
Microproces-
sors
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High-power5Vto3.xVDC-DCregulators
Low-voltage distributed power supplies
General Description
The HT82P604B provides complete control and
protection for a DC-DC converter optimized for
high performance microprocessor applications.
It is designed to drive two N-Channel
MOSFETs in a synchronous-rectified buck to-
pology. The HT82P604B integrates all of the
control, output adjustment, monitoring and
protection functions into a single package.
The output voltage of the converter is easily ad-
justed and precisely regulated. The HT82P604B
includes a 5-input digital-to-analog converter
(DAC) that adjusts the output voltage from 2.1V
to 3.5V in 0.1V increments and from 1.3V to
2.05V in 0.05V steps. The precision reference
and voltage-mode regulator hold the selected
output voltage to within
鹵1%
over temperature
and line voltage variations.
The HT82P604B provides simple, single feed-
back loop, voltage-mode control with fast tran-
s ie nt r es p ons e. It in cl ud es a 200k Hz
free-running triangle-wave oscillator that is
adjustable from below 50kHz to over 1MHz.
The error amplifier features a 15MHz
gain-bandwidth product and 6V/ms slew rate
which enables high converter bandwidth for
fast transient performance. The resulting
PWM duty ratio ranges from 0% to 100%.
The HT82P604B monitors the output voltage
with a window comparator that tracks the DAC
output and issues a Power Good signal when
the output is within
鹵10%.
The HT82P604B
protects against over-current conditions by in-
hibiting PWM operation. Built-in over-voltage
protection triggers an external SCR to crowbar
the input supply. The HT82P604B monitors the
current by using the r
DS (ON)
of the upper
MOSFET which eliminates the need for a cur-
rent sensing resistor.
Pentium is a trademark of Intel Corporation
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March 23, 2000
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