MAX8732 Datasheet, PDF (1/32 Pages) Maxim Integrated Products – High-Efficiency, Quad-Output, Main Power-Supply Controllers for Notebook Computers

19-3355; Rev 0; 8/04
High-Efficiency, Quad-Output, Main Power-
Supply Controllers for Notebook Computers
General Description
The MAX8732/MAX8733/MAX8734 dual step-down,
switch-mode power-supply (SMPS) controllers generate
logic-supply voltages in battery-powered systems. The
MAX8732/MAX8733/MAX8734 include two pulse-width
modulation (PWM) controllers, adjustable from 2V to 5.5V
or fixed at 5V and 3.3V. These devices feature two linear
regulators providing 5V and 3.3V always-on outputs. Each
linear regulator provides up to 100mA output current with
automatic linear-regulator bootstrapping to the main
SMPS outputs. The MAX8732/MAX8733/MAX8734 include
on-board power-up sequencing, a power-good (PGOOD)
output, digital soft-start, and internal soft-stop output dis-
charge that prevents negative voltages on shutdown.
Maxim’s proprietary Quick-PWM™ quick-response, con-
stant on-time PWM control scheme operates without
sense resistors and provides 100ns response to load tran-
sients while maintaining a relatively constant switching fre-
quency. The unique ultrasonic pulse-skipping mode
maintains the switching frequency above 25kHz, which
eliminates noise in audio applications. Other features
include pulse skipping, which maximizes efficiency in
light-load applications, and fixed-frequency PWM mode,
which reduces RF interference in sensitive applications.
The MAX8732 features a 200kHz/5V and 300kHz/3.3V
SMPS for highest efficiency, while the MAX8733 features
a 400kHz/5V and 500kHz/3.3V SMPS for “thin and light”
applications. The MAX8734 provides a pin-selectable
switching frequency, allowing either 200kHz/300kHz or
400kHz/500kHz operation of the 5V/3.3V SMPSs, respec-
tively. The MAX8732/MAX8733/MAX8734 are available in
28-pin QSOP packages and operate over the extended
temperature range (-40°C to +85°C).
The MAX8732/MAX8733/MAX8734 are pin-for-pin
upgrades to the MAX1777/MAX1977/MAX1999.
The MAX1999 Evaluation Kit can be used to evaluate
the MAX8732/MAX8733/MAX8734.
Applications
Notebook and Subnotebook Computers
PDAs and Mobile Communication Devices
3- and 4-Cell Li+ Battery-Powered Devices
Quick-PWM and Dual Mode are trademarks of Maxim
Integrated Products, Inc.
Features
♦ No Current-Sense Resistor Needed (MAX8734)
♦ Accurate Current Sense with Current-Sense
Resistor (MAX8732/MAX8733)
♦ 1.5% Output Voltage Accuracy
♦ 3.3V and 5V 100mA Bootstrapped Linear
Regulators
♦ Internal Soft-Start and Soft-Stop Output
Discharge
♦ Quick-PWM with 100ns Load Step Response
♦ 3.3V and 5V Fixed or Adjustable Outputs
(Dual Mode™)
♦ 4.5V to 24V Input Voltage Range
♦ Enhanced Ultrasonic Pulse-Skipping Mode
(25kHz min)
♦ Power-Good (PGOOD) Signal
♦ Overvoltage Protection Enable/Disable
Ordering Information
PART
TEMP RANGE
PIN-
PACKAGE
5V/3V
SWITCHING
FREQUENCY
MAX8732EEI -40°C to +85°C 28 QSOP 200kHz/300kHz
MAX8733EEI -40°C to +85°C 28 QSOP 400kHz/500kHz
MAX8734EEI -40°C to +85°C 28 QSOP
200kHz/300kHz or
400kHz/500kHz
Pin Configurations
TOP VIEW
N.C. 1
PGOOD 2
ON3 3
ON5 4
ILIM3 5
SHDN 6
FB3 7
REF 8
FB5 9
PRO 10
ILIM5 11
SKIP 12
TON 13
BST5 14
MAX8734
28 BST3
27 LX3
26 DH3
25 LDO3
24 DL3
23 GND
22 OUT3
21 OUT5
20 V+
19 DL5
18 LDO5
17 VCC
16 DH5
15 LX5
QSOP
Pin Configurations continued at end of data sheet.
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