Rainbow Electronics MAX6651 - Manual

General Description
The MAX6650/MAX6651 fan controllers use an
SMBus™/I
2 C™-compatible interface to regulate and mon-
itor the speed of 5VDC/12VDC brushless fans with built-in
tachometers. They automatically force the fan’s tachome-
ter frequency (fan speed) to match a preprogrammed
value in the Fan-Speed Register by using an external
MOSFET or bipolar transistor to linearly regulate the volt-
age across the fan. The MAX6650 regulates the speed of
a single fan by monitoring its tachometer output. The
MAX6651 also regulates the speed of a single fan, but it
contains additional tachometer inputs to monitor up to four
fans and control them as a single unit when they are used
in parallel.
The MAX6650/MAX6651 provide general-purpose
input/output (GPIO) pins that serve as digital inputs,
digital outputs, or various hardware interfaces. Capable
of sinking 10mA, these open-drain inputs/outputs can
drive an LED. To add additional hardware control, con-
figure GPIO1 to fully turn on the fan in case of software
failure. To generate an interrupt when a fault condition
is detected, configure GPIO0 to behave as an active-
low alert output. Synchronize multiple devices by set-
ting GPIO2 (MAX6651 only) as an internal clock output
or an external clock input.
The MAX6650 is available in a space-saving 10-pin
µMAX package, and the MAX6651 is available in a
small 16-pin QSOP package.
________________________Applications
RAID Desktop Computers
Servers Networking
Workstations Telecommunications
____________________________Features
♦ Closed/Open-Loop Fan-Speed Control for
5V/12V Fans
♦ 2-Wire SMBus/I 2 C-Compatible Interface
♦ Monitors Tachometer Output
Single Tachometer (MAX6650)
Up to Four Tachometers (MAX6651)
♦ Programmable Alert Output
♦ GPIOs
♦ Hardware Full-On Override
♦ Synchronize Multiple Fans
♦ Four Selectable Slave Addresses
♦ +3V to +5.5V Supply Voltage
♦ Small Packages
10-Pin µMAX (MAX6650)
16-Pin QSOP (MAX6651)
MAX6650/MAX6651
Fan-Speed Regulators and Monitors
with SMBus/I 2 C-Compatible Interface
________________________________________________________________ Maxim Integrated Products 1
19-1784; Rev 1; 9/01
Ordering Information
10 µMAX
PIN-PACKAGE TEMP. RANGE
-40°C to +85°C MAX6650EUB
PART
16 QSOP -40°C to +85°C MAX6651EEE
I 2 C is a trademark of Philips Corp.
SMBus is a trademark of Intel Corp.
MAX6650
V CC
SCL
10k
SDA
GPIO0 OUT
ADD
GND
FB
TACH0
V CC
3V TO 5.5V
V FAN
5V OR 12V
C COMP
10 µF
I 2 C/SMBus
INTERFACE
GPIO1
LED
FAN
FULL ON
ALERT
Typical Operating Circuit
Pin Configurations appear at end of data sheet.
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.