MAX786 Datasheet, PDF (1/20 Pages) Maxim Integrated Products – Dual-Output Power-Supply Controller for Notebook Computers

19-0160; Rev 2; 4/97
INFOERVMALAUTAIOTNIOINNCKLITUDED
Dual-Output Power-Supply
Controller for Notebook Computers
__________________General Description
The MAX786 is a system-engineered power-supply
controller for notebook computers or similar battery-
powered equipment. It provides two high-performance
step-down (buck) pulse-width modulators (PWMs)
for +3.3V and +5V. Other features include dual,
low-dropout, micropower linear regulators for
CMOS/RTC back-up, and two precision low-battery-
detection comparators.
High efficiency (95% at 2A; greater than 80% at loads
from 5mA to 3A) is achieved through synchronous recti-
fication and PWM operation at heavy loads, and
Idle Mode^TM operation at light loads. The MAX786 uses
physically small components, thanks to high operating
frequencies (300kHz/200kHz) and a new current-mode
PWM architecture that allows for output filter capacitors
as small as 30µF per ampere of load. Line- and load-
transient responses are terrific, with a high 60kHz unity-
gain crossover frequency allowing output transients to
be corrected within four or five clock cycles. Low sys-
tem cost is achieved through a high level of integration
and the use of low-cost, external N-channel MOSFETs.
Other features include low-noise, fixed-frequency PWM
operation at moderate to heavy loads, and a synchro-
nizable oscillator for noise-sensitive applications such
as electromagnetic pen-based systems and communi-
cating computers. The MAX786 is a monolithic,
BiCMOS IC available in fine-pitch, surface-mount
SSOP packages.
___________________________Applications
Notebook Computers
Portable Data Terminals
Communicating Computers
Pen-Entry Systems
________Typical Application Diagram
5.5V
TO
30V
SHUTDOWN
5V ON/OFF
3.3V ON/OFF
SYNC
MAX786
+3.3V
POWER
SECTION
µP
MEMORY
+5V PERIPHERALS
POWER-GOOD
LOW-BATTERY WARNING
SUSPEND POWER
________________________________Features
o Dual PWM Buck Controllers (+3.3V and +5V)
o Two Precision Comparators or Level Translators
o 95% Efficiency
o 420µA Quiescent Current, 70µA in Standby
(linear regulators alive)
o 25µA Shutdown Current (+5V linear alive)
o 5.5V to 30V Input Range
o Small SSOP Package
o Fixed Output Voltages:
3.3V (standard)
3.45V (High-Speed Pentium™)
3.6V (PowerPC™)
_________________Ordering Information
PART
MAX786CAI
MAX786RCAI
TEMP. RANGE
0°C to +70°C
0°C to +70°C
PIN-PACKAGE
28 SSOP
28 SSOP
V_OUT
3.3V
3.45V
Ordering Information continued at end of data sheet.
_____________________Pin Configuration
TOP VIEW
CS3 1
SS3 2
ON3 3
D1 4
D2 5
VH 6
Q2 7
Q1 8
GND 9
REF 10
SYNC 11
SHDN 12
ON5 13
SS5 14
MAX786
SSOP
28 ^FB3
27 DH3
26 LX3
25 BST3
24 DL3
23 V+
22 VL
21 FB5
20 PGND
19 DL5
18 BST5
17 LX5
16 DH5
15 CS5
Idle Mode is a trademark of Maxim Integrated Products. Pentium is a trademark of Intel Corp. PowerPC is a trademark of IBM Corp.
_______________________________________________________________________ Maxim Integrated Products 1
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