HT82P604B Datasheet, PDF (1/7 Pages) Holtek Semiconductor Inc – DC-DC Converter

Preliminary
HT82P604B
DC-DC Converter
Features
· Operating voltage: 5V~12V
· Drives two N-Channel MOSFETs
· Simple single-loop control design
- _{Voltage-mode PWM control}
· Fast transient response
- _{High-bandwidth error amplifier}
- _{Full 0% to 100% duty ratio}
· Excellent output voltage regulation
- _{±1% over line voltage and temperature}
· 5 bit digital-to-analog output voltage selection
- _{Wide range -1.3V to 3.5V}
- _{0.1V binary steps from 2.1V to 3.5V}
- _{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¢s r_{DS (ON)}
· Small converter size
- _{Constant frequency operation}
- _{200kHz free-running oscillator program-}
mable from 50kHz to over 1MHz
Applications
· Power supply for Pentium^TM, Pentium^TM
Pro, PowerPC^TM and Alpha^TM Microproces-
sors
· 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 ±1% over temperature
and line voltage variations.
The HT82P604B provides simple, single feed-
back loop, voltage-mode control with fast tran-
sient response. It includes a 200kHz
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 ±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
1
March 23, 2000