MAX8732A Datasheet, PDF (1/33 Pages) Maxim Integrated Products – High-Efficiency, Quad-Output, Main Power-Supply Controllers for Notebook Computers

19-3711; Rev 0; 5/05
High-Efficiency, Quad-Output, Main Power-
Supply Controllers for Notebook Computers
General Description
The MAX8732A/MAX8733A/MAX8734A dual step-down,
switch-mode power-supply (SMPS) controllers generate
logic-supply voltages in battery-powered systems. The
MAX8732A/MAX8733A/MAX8734A 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 out-
puts. Each linear regulator provides up to 100mA output
current with automatic linear-regulator bootstrapping to
the main SMPS outputs. The MAX8732A/MAX8733A/
MAX8734A include on-board power-up sequencing, a
power-good (PGOOD) output, digital soft-start, and inter-
nal soft-stop output discharge that prevents negative volt-
ages on shutdown. Additionally, the outputs are high
impedance when V_CC falls below its UVLO set point while
the outputs are enabled.
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 MAX8732A features a 200kHz/5V and 300kHz/3.3V
SMPS for highest efficiency, while the MAX8733A fea-
tures a 400kHz/5V and 500kHz/3.3V SMPS for “thin and
light” applications. The MAX8734A provides a pin-
selectable switching frequency, allowing either 200kHz/
300kHz or 400kHz/500kHz operation of the 5V/3.3V
SMPSs, respectively. The MAX8732A/MAX8733A/
MAX8734A are available in 28-pin QSOP packages and
operate over the extended temperature range
(-40°C to +85°C).
The MAX8732A/MAX8733A/MAX8734A are pin-for-pin
upgrades to the MAX1777/MAX1977/MAX1999.
The MAX1999 evaluation kit (EV kit) can be used to
evaluate the MAX8732A/MAX8733A/MAX8734A.
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 (MAX8734A)
♦ Accurate Current Sense with Current-Sense
Resistor (MAX8732A/MAX8733A)
♦ 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-
PA CKA GE
MAX8732AEEI+ -40°C to +85°C 28 QSOP
5V/3.3V
SWITCHING
FREQUENCY
(kHz)
200/300
MAX8732AEEI -40°C to +85°C 28 QSOP
200/300
MAX8733AEEI+ -40°C to +85°C 28 QSOP
400/500
MAX8733AEEI -40°C to +85°C 28 QSOP
400/500
Ordering Information continued at end of data sheet.
+Denotes lead-free package.
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
MAX8734A
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.
________________________________________________________________ Maxim Integrated Products 1
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