ADT7476
Rev. B | Page 7 of 72
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
05382-003
20
19
18
17
16
15
14
13
+5V
IN
VID4/GPIO4
D1+
D1–
24
23
22
21
PWM1/XTO
V
CCP
+2.5V
IN
/THERM
+12V
IN
/VID5
D2+
D2–
PWM3/ADDREN
TACH4/THERM/SMBALERT/GPIO6/ADDR SELECT
5
6
7
8
9
10
11
12
VID0/GPIO0
VID1/GPIO1
VID2/GPIO2
VID3/GPIO3
TACH1
TACH2
TACH3
PWM2/SMBALERT
1
2
3
4
SDA
SCL
GND
V
CC
ADT7476
TOP VIEW
(Not to Scale)
Figure 3. Pin Configuration
Table 4. Pin Function Descriptions
Pin No.
Mnemonic
Description
1
SDA
Digital I/O (Open Drain). SMBus bidirectional serial data. Requires SMBus pull-up.
2
SCL
Digital Input (Open Drain). SMBus serial clock input. Requires SMBus pull-up.
3 GND
Ground
Pin.
4 V
CC
Power Supply. Powered by 3.3 V standby, if monitoring in low power states is required. V
CC
is also monitored
through this pin.
5
VID0
Digital Input. Voltage supply readouts from CPU. This value is read into the VID code register (0x43).
GPIO0
General-Purpose Open-Drain Digital I/O.
6
VID1
Digital Input. Voltage supply readouts from CPU. This value is read into the VID code register (0x43).
GPIO1
General-Purpose Open-Drain Digital I/O.
7
VID2
Digital Input. Voltage supply readouts from CPU. This value is read into the VID code register (0x43).
GPIO2
General-Purpose Open-Drain Digital I/O.
8
VID3
Digital Input. Voltage supply readouts from CPU. This value is read into the VID code register (0x43).
GPIO3
General-Purpose Open-Drain Digital I/O.
9
TACH3
Digital Input (Open Drain). Fan tachometer input to measure speed of Fan 3.
10 PWM2 Digital Output (Open Drain). Requires 10 kΩ typical pull-up. Pulse-width modulated output to control Fan 2
speed. Can be configured as a high or low frequency drive.
SMBALERT
Digital Output (Open Drain). This pin can be reconfigured as an SMBALERT interrupt output to signal out-of-
limit conditions.
11
TACH1
Digital Input (Open Drain). Fan tachometer input to measure speed of Fan 1.
12
TACH2
Digital Input (Open Drain). Fan tachometer input to measure speed of Fan 2.
13 PWM3 Digital I/O (Open Drain). Pulse-width modulated output to control Fan 3 and Fan 4 speed. Requires 10 kΩ typical
pull-up. Can be configured as a high or low frequency drive.
ADDREN
If pulled low on power-up, the ADT7476 enters address select mode, and the state of Pin 14 (ADDR SELECT)
determines the ADT7476 slave address.
14
TACH4
Digital Input (Open Drain). Fan tachometer input to measure speed of Fan 4.
THERM
Alternatively, the pin can be reconfigured as a bidirectional THERM pin. Use to time and monitor assertions on
the THERM input. For example, can be connected to the PROCHOT output of an Intel® Pentium® 4 processor or
to the output of a trip point temperature sensor. Can be used as an output to signal overtemperature
conditions.
SMBALERT
Digital Output (Open Drain). This pin can be reconfigured as an SMBALERT interrupt output to signal out-of-
limit conditions.
GPIO6
General-Purpose Open-Drain Digital I/O.
ADDR SELECT
If in address select mode, the logic state of this pin defines the SMBus device address.
15
D2–
Cathode Connection to Second Thermal Diode.
16
D2+
Anode Connection to Second Thermal Diode.
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