19-0160; Rev 2; 4/97
IT
TION K
ED
VALUA
E
INCLUD
ATION
INFORM
Dual-Output Power-Supply
Controller for Notebook Computers
________________________________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™)
__________________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.
MAX786
_________________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
28
FB3
27
DH3
26
LX3
25
BST3
___________________________Applications
Notebook Computers
Portable Data Terminals
Communicating Computers
Pen-Entry Systems
MAX786
24
DL3
23
V+
22
VL
21
FB5
20
PGND
19
DL5
18
BST5
17
LX5
16
DH5
15
CS5
________Typical Application Diagram
+3.3V
5.5V
TO
30V
SHUTDOWN
5V ON/OFF
3.3V ON/OFF
SYNC
POWER
SECTION
µP
MEMORY
+5V PERIPHERALS
Q2
7
Q1
8
GND
9
REF
10
SYNC
11
SHDN
12
ON5
13
SS5
14
MAX786
POWER-GOOD
LOW-BATTERY WARNING
SUSPEND POWER
SSOP
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
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
