ADM1026
Table 14. Register 01h, Configuration Register 2 (Power-On Default 00h)
Bit Name R/W Description
Enable GPIO0/Fan0 = 0 R/W
When this bit is ±, Pin 3 is enabled as a general-purpose I/O pin (GPIO0), otherwise it is a fan tach
0
±
2
3
4
5
6
7
measurement input (Fan 0).
When this bit is ±, Pin 4 is enabled as a general-purpose I/O pin (GPIO±), otherwise it is a fan tach
measurement input (Fan ±).
When this bit is ±, Pin 5 is enabled as a general-purpose I/O pin (GPIO2), otherwise it is a fan tach
measurement input (Fan 2).
When this bit is ±, Pin 6 is enabled as a general-purpose I/O pin (GPIO3), otherwise it is a fan tach
measurement input (Fan 3).
When this bit is ±, Pin 9 is enabled as a general-purpose I/O pin (GPIO4), otherwise it is a fan tach
measurement input (Fan 4).
When this bit is ±, Pin ±0 is enabled as a general-purpose I/O pin (GPIO5), otherwise it is a fan tach
measurement input (Fan 5).
When this bit is ±, Pin ±± is enabled as a general-purpose I/O pin (GPIO6), otherwise it is a fan tach
measurement input (Fan 6).
When this bit is ±, Pin ±2 is enabled as a general-purpose I/O pin (GPIO7), otherwise it is a fan tach
measurement input (Fan 7).
Enable GPIO±/Fan± = 0 R/W
Enable GPIO2/Fan2 = 0 R/W
Enable GPIO3/Fan3 = 0 R/W
Enable GPIO4/Fan4 = 0 R/W
Enable GPIO5/Fan5 = 0 R/W
Enable GPIO6/Fan6 = 0 R/W
Enable GPIO7/Fan7 = 0 R/W
Table 15. Register 02h, Fans 0 to 3 Fan Divisor Register (Power-On Default 55h)
Bit
Name
R/W Description
±–0
Fan 0 Divisor
R/W Sets the oscillator prescaler division ratio for Fan 0 speed measurement. The division ratios, oscillator
frequencies, and typical fan speeds (based on 2 tach pulses per revolution) are as follows:
Oscillator
Frequency (kHz)
Code
Divide By
Fan Speed (RPM)
00
0±
±0
±±
±
2
4
8
22.5
±±.25
5.62
2.8±
8800, nominal, for count of ±53
4400, nominal, for count of ±53
2200, nominal, for count of ±53
±±00, nominal, for count of ±53
3–2
5–4
7–6
Fan ± Divisor
Fan 2 Divisor
Fan 3 Divisor
R/W Same as Fan 0
R/W Same as Fan 0
R/W Same as Fan 0
Table 16. Register 03h, Fans 4 to 7 Fan Divisor Register (Power-On Default 55h)
Bit
Name
R/W Description
±–0
Fan 4 Divisor
R/W Sets the oscillator prescaler division ratio for Fan 4 speed measurement. The division ratios, oscillator
frequencies, and typical fan speeds (based on 2 tach pulses per revolution) are as follows:
Oscillator
Frequency (kHz)
Code
Divide By
Fan Speed (RPM)
00
0±
±0
±±
±
2
4
8
22.5
±±.25
5.62
2.8±
8800, nominal, for count of ±53
4400, nominal, for count of ±53
2200, nominal, for count of ±53
±±00, nominal, for count of ±53
3-2
5-4
7-6
Fan 5 Divisor
Fan 6 Divisor
Fan 7 Divisor
R/W Same as Fan 4
R/W Same as Fan 4
R/W Same as Fan 4
Table 17. Register 04h, DAC Control Register (Power-On Default FFh)
Bit
Name
R/W Description
7–0
DAC Control
R/W This register contains the value to which the fan speed DAC is programmed in normal mode, or the
4 MSBs contain the minimum fan speed in auto fan speed control mode.
Rev. A | Page 39 of 56
ADI [ ADI ]
