ADT7466
Rev. 2 | Page 7 of 48 | www.onsemi.com
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
04711-002
ADT7466
TOP VIEW
(Not to Scale)
DRIVE1
1
SCL
16
TACH1
2
SDA
15
DRIVE2
3
ALERT
14
TACH2
4
REFOUT
13
GND
5
AIN2/TH2/D2+
12
V
CC
6
AIN1/TH1/D2–
11
FAN1_ON/PROCHOT/THERM
7
D1+
10
FANLOCK
8
D1–
9
Figure 3. Pin Configuration
Table 3. Pin Function Descriptions
Pin No. Mnemonic Type Description
1 DRIVE1 Analog
Output
Output of 8-Bit DAC Controlling Fan 1 Speed.
2 TACH1 Digital
Input
Fan Tachometer Input to Measure Speed of Fan 1.
3 DRIVE2 Analog
Output
Output of 8-Bit DAC Controlling Fan 2 Speed.
4 TACH2 Digital
Input
Fan Tachometer Input to Measure Speed of Fan 2.
5 GND Ground Ground Pin for Analog and Digital Circuitry.
6 V
CC
Power
supply
3.3 V Power Supply. V
CC
is also monitored through this pin.
7 FAN1_ON/
PROCHOT
/
THERM
Digital I/O If configured as FAN1_ON, this pin is the open-drain control signal output for the dc-dc
converter. Active (high) when DRIVE1 > V_FAN_MIN.
If configured as
PROCHOT
, the input can be connected to the
PROCHOT
output of the
Intel Pentium 4 processor to time and monitor
PROCHOT
assertions.
If configured as
THERM
, this pin is the interrupt output to flag critical thermal events.
8
FANLOCK
Digital
Output
Open-Drain Digital Output. This output is asserted (low) when either of the fans stall or
fail to spin up.
9 D1− Analog
Input
Cathode Connection to Thermal Diode 1.
10 D1+ Analog
Input
Anode Connection to Thermal Diode 1.
11 AIN1/TH1/D2− Analog
input
0 V to 2.25 V Analog Input. Can be reconfigured as thermistor input or as a cathode
connection to Thermal Diode 2. Configured for thermistor connection by default.
12 AIN2(TH2)/D2+ Analog
Input
0 V to 2.25 V Analog Input. Can be reconfigured as thermistor input or as an anode
connection to Thermal Diode 2. Configured for thermistor connection by default.
13 REFOUT Analog
Output
2.25 V Reference Voltage Output, 20 mA maximum output current.
14
ALERT
Digital
Output
Open-Drain Digital Output. The SMBus
ALERT
pin alerts the system to out-of-limit events
such as a failed fan, overtemperature, or out-of-limit analog measurement.
15 SDA Digital I/O Open-Drain Digital I/O. SMBus bidirectional serial data. Requires SMBus pull-up resistor.
16 SCL Digital
Input
Open-Drain Digital Input. SMBus serial clock input. Requires SMBus pull-up resistor.
