Rainbow Electronics MAX786 - Manual

__________________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
________________________________Features
♦ Dual PWM Buck Controllers (+3.3V and +5V)
♦ Two Precision Comparators or Level Translators
♦ 95% Efficiency
♦ 420µA Quiescent Current, 70µA in Standby
(linear regulators alive)
♦ 25µA Shutdown Current (+5V linear alive)
♦ 5.5V to 30V Input Range
♦ Small SSOP Package
♦ Fixed Output Voltages:
3.3V (standard)
3.45V (High-Speed Pentium™)
3.6V (PowerPC™)
_________________Ordering Information
MAX786
Dual-Output Power-Supply
Controller for Notebook Computers
_______________________________________________________________________ Maxim Integrated Products 1
19-0160; Rev 2; 4/97
_____________________Pin Configuration
28
27
26
25
24
23
22
21
1
2
3
4
5
6
7
8
FB3
DH3
LX3
BST3 D1
ON3
SS3
CS3
TOP VIEW
DL3
V+
VL
FB5 Q1
Q2
VH
D2
20
19
18
17
9
10
11
12
PGND
DL5
BST5
LX5 SHDN
SYNC
REF
GND
SSOP
MAX786
16
15
13
14
DH5
CS5 SS5
ON5
Idle Mode is a trademark of Maxim Integrated Products. Pentium is a trademark of Intel Corp. PowerPC is a trademark of IBM Corp.
________Typical Application Diagram
MAX786
5.5V
TO
30V
SHUTDOWN
POWER
SECTION
POWER-GOOD
LOW-BATTERY WARNING
µ P
MEMORY
PERIPHERALS
+3.3V
+5V
5V ON/OFF
3.3V ON/OFF
SYNC
SUSPEND POWER
28 SSOP 0°C to +70°C MAX786RCAI
28 SSOP 0°C to +70°C MAX786CAI
PIN-PACKAGE TEMP. RANGE PART
3.45V
3.3V
V OUT
Ordering Information continued at end of data sheet.
EVALUATION KIT
INFORMATION INCLUDED
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.