19-1574; Rev 0; 1/00
Fan Controller and Remote Temperature Sensor
with SMBus Serial Interface
General Description
Features
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 3ꢀ° 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 D° 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 DA° output that generates
a variable D° control voltage. In PWM mode, the FAN
frequency can be synchronized to an external clock.
ꢀ 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
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 AD° 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.
ꢀ ±±3C Temperature Accuracy (-ꢀ03C to ꢁ12ꢂ3Cꢃ
remote)
ꢀ ±µA Standby Supply Current
ꢀ ꢁ±V to ꢁꢂ.ꢂV Supply Range
ꢀ Small 16-Pin QSOP Package
The MAX1669 is available in a space-saving 16-pin
QSOP package that allows it to fit adjacent to the
SLOT1 connector.
Ordering Information
PART
TEMP. RANGE
PIN-PACKAGE
Applications
MAX1669EEE
-40ꢀ° to +85ꢀ°
16 QSOP
®
Pentium °PU °ooling
Desktop °omputers
Notebook °omputers
Servers
Pin Configuration
Workstations
TOP VIEW
I/O1
I/O2
1
2
3
4
5
6
7
8
16 OVERT
15 ALERT
ADD0
ADD1
ADD2
AGND
DXN
14 SMBDATA
Typical Operating Circuit appears at end of data sheet.
MAX1669
13 SMBCLK
12 PGND
11 FAN
10 SYNC
DXP
9
V
CC
QSOP
Pentium is a registered trademark of Intel Corp.
________________________________________________________________ Maxim Integrated Products
1
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