ADM1026

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4

Table 3. PIN ASSIGNMENT

Pin No.

Description

Type

Mnemonic

17

INT

Digital Output

Interrupt Request (Open Drain). The output is enabled when Bit 1 of the

configuration register is set to 1. The default state is disabled. It has an on-chip

100 kW pullup resistor.

18

PWM

Digital Output

Open drain pulse width modulated output for control of the fan speed. This pin

defaults to high for the 100% duty cycle for use with NMOS drive circuitry. If a

PMOS device is used to drive the fan, the PWM output may be inverted by setting

Bit 1 of Test Register 1 = 1.

19

RESETSTBY

Digital Output

Power-on Reset. 5 mA driver (weak 100 kW pullup), active low output (100 kW

pullup) with a 180 ms typical pulse width. RESETSTBY is asserted whenever

3.3 V STBY is below the reset threshold. It remains asserted for approximately

180 ms after 3.3 V STBY rises above the reset threshold.

20

RESETMAIN

Digital I/O

Power-on Reset. 5 mA driver (weak 100 kW pullup), active low output (100 kW

pullup) with a 180 ms typical pulse width. RESETMAIN is asserted whenever 3.3 V

MAIN is below the reset threshold. It remains asserted for approximately 180 ms

after 3.3 V MAIN rises above the reset threshold. If, however, 3.3 V STBY rises with

or before 3.3 V MAIN, then RESETMAIN remains asserted for 180 ms after

RESETSTBY is deasserted. Pin 20 also functions as an active low RESET input.

21

AGND

Ground

Ground pin for analog circuits.

22

3.3 V STBY

Power Supply

Supplies 3.3 V power. Also monitors the 3.3 V standby power rail.

23

DAC

Analog Output

0 V to 2.5 V output for analog control of the fan speed.

24

Analog Output

Reference Voltage Output. Can be selected as 1.8 V (default) or 2.5 V.

25

D1–/NTESTIN

Analog Input

Connected to a cathode of the first remote temperature sensing diode. If it is held

high at power-on, it activates the NAND tree test mode.

26

D1+

Analog Input

Connected to the anode of the first remote temperature sensing diode.

27

Programmable

Connected to the cathode of the second remote temperature sensing diode or the

analog input may be reconfigured as a 0 V − 2.5 V analog input.

28

Programmable

Connected to the anode of the second remote temperature sensing diode, or the

analog input may be reconfigured as a 0 V − 2.5 V analog input.

29

Analog Input

Monitors battery voltage, nominally +3.0 V.

30

Analog Input

Monitors the +5.0 V supply.

31

Analog Input

Monitors the −12 V supply.

32

Analog Input

Monitors the +12 V supply.

33

Analog Input

Monitors the processor core voltage (0 V to 3.0 V).

34

Analog Input

General-purpose 0 V to 2.5 V analog inputs.

35

Analog Input

General-purpose 0 V to 2.5 V analog inputs.

36

Analog Input

General-purpose 0 V to 3.0 V analog inputs.

37

Analog Input

General-purpose 0 V to 3.0 V analog inputs.

38

Analog Input

General-purpose 0 V to 3.0 V analog inputs.

39

Analog Input

General-purpose 0 V to 3.0 V analog inputs.

40

Analog Input

General-purpose 0 V to 3.0 V analog inputs.

41

Analog Input

General-purpose 0 V to 3.0 V analog inputs.

42

GPIO16/THERM

General-purpose I/O pin that can be configured as a digital input or output. Can

also be configured as a bidirectional THERM pin (100 kW pullup).

43

GPIO15

General-purpose I/O pin that can be configured as a digital input or output.

44

GPIO14

General-purpose I/O pin that can be configured as a digital input or output.

45

GPIO13

General-purpose I/O pin that can be configured as a digital input or output.

46

GPIO12

General-purpose I/O pin that can be configured as a digital input or output.

47

GPIO11

General-purpose I/O pin that can be configured as a digital input or output.

48

GPIO10

General-purpose I/O pin that can be configured as a digital input or output.

†GPIO pins are open drain and require external pullup resistors. Fan inputs have integrated 10 kW pullups, but these pins become open drain

when reconfigured as GPIOs.