ADT7473_11 ONSEMI [ON Semiconductor], ADT7473_11 Datasheet - Page 9

• Manufacturer Part Number: ADT7473_11
• Description: dbCOOL Remote Thermal Monitor and Fan Control
• Manufacturer: ONSEMI [ON Semiconductor]

Serial Bus Interface
is carried out using the SMBus. The ADT7473/ADT7473−1
is connected to this bus as a slave device, under the control of
a master controller, which is usually (but not necessarily) the
ICH.
0101110 or 0x2E. The read/write bit must be added to get the
8−bit address (01011100 or 0x5C). When the ADT7473−1
is powered up with Pin 8 (PWM3/ADDREN) high, the
ADT7473−1 has a default SMBus address of 0101110 or
0x2E. If more than one ADT7473−1 is used in a system,
each ADT7473−1 is placed in ADDR SELECT mode by
strapping Pin 8 low on powerup. The logic state of Pin 4 then
determines the device’s SMBus address. The logic of these
pins is sampled on powerup.
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 change
in the address has no effect after this.
Table 3. Hardwiring the ADT7473−1 SMBus Device
Address
On PCs and servers, control of the ADT7473/ADT7473−1
The ADT7473 has a fixed 7−bit serial bus address of
The device address is sampled on powerup and latched on
Pin 13 State
0
0
1
Low (10 kW to GND)
High (10 kW pullup)
Don’t care
Pin 14 State
FRONT
CHASSIS
FAN
REAR
CHASSIS
FAN
AMBIENT
TEMPERATURE
0101100 (0x2C)
0101101 (0x2D)
0101110 (0x2E)
Address
Figure 12. ADT7473 Configuration
http://onsemi.com
TACH2
PWM3
TACH3
D1+
D1–
ADT7473
GND
9
SMBALERT
THERM
TACH1
PWM1
SDA
SCL
D2+
D2–
Figure 15. SMBus Address = 0x2D (Pin 4 = 1)
Figure 14. SMBus Address = 0x2C (Pin4 = 0)
Figure 13. Default SMBus Address = 0x2E
PROCHOT
PWM3/ADDREN
ADT7473−1
ADT7473−1
ADT7473−1
PWM3/ADDREN
PWM3/ADDREN
ADDR SELECT
ADDR SELECT
ADDR SELECT
CPU FAN
ICH
CPU
4
8
ADDRESS = 0x2E
4
8
ADDRESS = 0x2C
4
8
ADDRESS = 0x2D
V
10kΩ
V
CC
CC
10kΩ
10kΩ