Rainbow Electronics MAX1669 - Manual

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General Description
The MAX1669 fan controller includes a precise digital
thermometer that reports the temperature of a remote
sensor. The remote sensor is a diode-connected transis-
tor—typically a low-cost, easily mounted 2N3906 PNP
type—replacing conventional thermistors or thermocou-
ples. Remote accuracy is ±3°C for transistors from multi-
ple manufacturers, with no calibration needed. The
MAX1669 has an independent fan controller with a low-
current logic output requiring external power compo-
nents to interface to a DC brushless fan. The fan
controller has two modes of operation: a low-frequency
(20Hz to 160Hz) PWM mode intended for driving the fan
motor, or a high-impedance DAC output that generates
a variable DC control voltage. In PWM mode, the FAN
frequency can be synchronized to an external clock.
Other key features include general-purpose inputs/out-
puts (GPIOs) for fan presence detection and a thermo-
stat output intended as a fan override signal in case the
host system loses the ability to communicate. The inter-
nal ADC has a wide input voltage range and gives
overrange readings when too large an input voltage is
applied. Other error-checking includes temperature
out-of-range indication and diode open/short faults.
The MAX1669 is available in a space-saving 16-pin
QSOP package that allows it to fit adjacent to the
SLOT1 connector.
Applications
Pentium
®
CPU Cooling
Desktop Computers
Notebook Computers
Servers
Workstations
Features
♦ Measures Remote CPU Temperature
♦ No Calibration Required
♦ 20Hz to 160Hz PWM Output for Fan
♦ PWM Frequency Sync Input (260kHz)
♦ Flexible Fan Interface: Linear or PWM
♦ SMBus 2-Wire Serial Interface
♦ Programmable Under/Overtemperature Alarms
♦ ALERT Latched Interrupt Output
♦ OVERT Thermostat Output
♦ Two GPIO Pins
♦ Write-Once Configuration Protection
♦ Supports SMBus Alert Response
♦ ±3°C Temperature Accuracy (-40°C to +125°C,
remote)
♦ 3µA Standby Supply Current
♦ +3V to +5.5V Supply Range
♦ Small 16-Pin QSOP Package
MAX1669
Fan Controller and Remote Temperature Sensor
with SMBus Serial Interface
________________________________________________________________ Maxim Integrated Products 1
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
I/O1 OVERT
ALERT
SMBDATA
SMBCLK
PGND
FAN
SYNC
V CC
TOP VIEW
MAX1669
QSOP
I/O2
ADD0
AGND
ADD1
ADD2
DXN
DXP
19-1574; Rev 0; 1/00
PART
MAX1669EEE -40°C to +85°C
TEMP. RANGE PIN-PACKAGE
16 QSOP
Pentium is a registered trademark of Intel Corp.
Pin Configuration
Ordering Information
Typical Operating Circuit appears at end of data sheet.