adt7476a Analog Devices, Inc., adt7476a Datasheet - Page 11

• Manufacturer Part Number: adt7476a
• Description: Dbcool Remote Thermal Controller And Voltage Monitor
• Manufacturer: Analog Devices, Inc.

SERIAL BUS INTERFACE
Control of the ADT7476A is carried out using the serial system
management bus (SMBus). The ADT7476A is connected to this
bus as a slave device, under the control of a master controller.
The ADT7476A has a 7-bit serial bus address. When the device
is powered up with Pin 13 (PWM3/ ADDREN ) high, the
ADT7476A has a default SMBus address of 0101110 or 0x2E.
The read/write bit must be added to get the 8-bit address.
If more than one ADT7476A is to be used in a system, each
ADT7476A is placed in ADDR SELECT mode by strapping
Pin 13 low on power-up. The logic state of Pin 14 then
determines the device’s SMBus address. The logic of these
pins is sampled on power-up.
The device address is sampled on power-up and latched on
the first valid SMBus transaction, more precisely on the low-to-
high transition at the beginning of the eighth SCL pulse, when
the serial bus address byte matches the selected slave address.
The selected slave address is chosen using the ADDREN pin/
ADDR SELECT pin. Any attempted changes in the address
have no effect after this.
Table 5. Hardwiring the ADT7476A SMBus Device Address
Pin 13 State
0
0
1
Pin 14
Low (10 kΩ to GND)
High (10 kΩ pull-up)
Don’t Care
FRONT
CHASSIS
FAN
REAR
CHASSIS
FAN
AMBIENT
TEMPERATURE
Address
0101100 (0x2C)
0101101 (0x2D)
0101110 (0x2E)
Figure 13. ADT7476A Configuration
Rev. 0 | Page 11 of 72
TACH2
PWM3
TACH3
D1+
D1–
V
+5V
+12V
CC
IN
IN
ADT7476A
/VID5
VID[0:4]/VID[0:5]
GND
SMBALERT
THERM
TACH1
PWM1
SDA
SCL
D2+
D2–
5(VRM9)/6(VRM10)
PROCHOT
Figure 15. SMBus Address = 0x2C (Pin 14 = 0)
Figure 16. SMBus Address = 0x2D (Pin 14 = 1)
Figure 14. Default SMBus Address = 0x2E
PWM3/ADDREN
ADT7476A
ADT7476A
PWM3/ADDREN
ADT7476A
PWM3/ADDREN
ADDR SELECT
ADDR SELECT
ADDR SELECT
14
13
ADDRESS = 0x2E
14
13
ADDRESS = 0x2C
14
13
ADDRESS = 0x2D
V
10kΩ
V
CC
CC
10kΩ
10kΩ
ADT7476A