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MAX8764 Datasheet, PDF (1/23 Pages) Maxim Integrated Products – High-Speed, Step-Down Controller with Accurate Current Limit for Notebook Computers
19-3626; Rev 0; 3/05
High-Speed, Step-Down Controller with
Accurate Current Limit for Notebook Computers
General Description
The MAX8764 pulse-width modulation (PWM) controller
provides high efficiency, excellent transient response,
and high-DC output accuracy needed for stepping
down high-voltage batteries to generate low-voltage
CPU core or chipset/RAM supplies in notebook com-
puters.
Maxim’s proprietary Quick-PWM™ quick-response,
constant-on-time PWM control scheme handles wide
input/output voltage ratios with ease and provides
100ns “instant-on” response to load transients while
maintaining a relatively constant switching frequency.
Efficiency is enhanced by an ability to drive very large
synchronous-rectifier MOSFETs. Accurate current sens-
ing to ensure reliable overload protection is available
using an external current-sense resistor in series with
the synchronous rectifier. Alternatively, the synchronous
rectifier itself can be used for less-accurate current
sensing at the lowest possible power dissipation. A
high-output impedance in shutdown eliminates nega-
tive output voltages, saving the cost of a Schottky diode
on the output.
Single-stage buck conversion allows the MAX8764 to
directly step down high-voltage batteries for the highest
possible efficiency. Alternatively, two-stage conversion
(stepping down the 5V system supply instead of the
battery) at a higher switching frequency allows the mini-
mum possible physical size.
The MAX8764 is intended for CPU core, chipset,
DRAM, or other low-voltage supplies as low as 1V. It is
available in 20-pin QSOP and thin QFN packages and
includes both adjustable overvoltage and undervoltage
protection.
For a dual step-down PWM controller with accurate cur-
rent limit, refer to the MAX8743 data sheet. The
MAX1714/MAX1715 single/dual PWM controllers are
similar to the MAX8764, but do not use current-sense
resistors.
Notebook Computers
Applications
CPU Core Supplies
Chipset/RAM Supplies as Low as 1V
1.8V and 2.5V Supplies
Quick-PWM is a trademark of Maxim Integrated Products, Inc.
Pin Configurations appear at end of data sheet.
Features
♦ Ultrahigh Efficiency
♦ Accurate Current-Limit Option
♦ Quick-PWM with 100ns Load-Step Response
♦ 1% VOUT Accuracy Over Line and Load
♦ 1.8V/2.5V Fixed or 1V to 5.5V Adjustable Output
Range
♦ 2V to 28V Battery Input Range
♦ 200/300/450/600kHz Switching Frequency
♦ Adjustable Overvoltage Protection
♦ Adjustable Undervoltage Protection
♦ 1.7ms Digital Soft-Start
♦ Drives Large Synchronous-Rectifier FETs
♦ 2V ±1% Reference Output
♦ Power-Good Window Comparator
Ordering Information
PART
TEMP RANGE PIN-PACKAGE
MAX8764EEP
-40°C to +85°C
MAX8764EEP+
-40°C to +85°C
MAX8764ETP
-40°C to +85°C
MAX8764ETP+
-40°C to +85°C
+Denotes lead-free package.
20 QSOP
20 QSOP
20 Thin QFN
20 Thin QFN
Minimal Operating Circuit
5V INPUT
BATTERY
4.5V TO 28V
VCC
VDD
SHDN
V+
UVP
ILIM
BST
DH
MAX8764
REF
LX
DL
PGOOD CS
LATCH
OVP
OUT
FB
SKIP
GND
OUTPUT
2.5V
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.