ADM1026
Pin No.
18
Mnemonic
PWM
Type
Digital Output
Description
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.
Power-On Reset. 5 mA driver (weak 100 kΩ pull-up), active low output (100 kΩ pull-up)
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.
Power-On Reset. 5 mA driver (weak 100 kΩ pull-up), active low output (100 kΩ pull-up)
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.
Ground pin for analog circuits.
Supplies 3.3 V power. Also monitors the 3.3 V standby power rail.
0 V to 2.5 V output for analog control of the fan speed.
Reference Voltage Output. Can be selected as 1.8 V (default) or 2.5 V.
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.
Connected to the anode of the first remote temperature sensing diode.
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.
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.
Monitors battery voltage, nominally +3 V.
Monitors the +5 V supply.
Monitors the
−12
V supply.
Monitors the +12 V supply.
Monitors the processor core voltage (0 V to 3.0 V).
General-purpose 0 V to 2.5 V analog inputs.
General-purpose 0 V to 2.5 V analog inputs.
General-purpose 0 V to 3 V analog inputs.
General-purpose 0 V to 3 V analog inputs.
General-purpose 0 V to 3 V analog inputs.
General-purpose 0 V to 3 V analog inputs.
General-purpose 0 V to 3 V analog inputs.
General-purpose 0 V to 3 V analog inputs.
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 kΩ pull-up).
General-purpose I/O pin that can be configured as a digital input or output.
General-purpose I/O pin that can be configured as a digital input or output.
General-purpose I/O pin that can be configured as a digital input or output.
General-purpose I/O pin that can be configured as a digital input or output.
General-purpose I/O pin that can be configured as a digital input or output.
General-purpose I/O pin that can be configured as a digital input or output.
19
RESETSTBY
Digital Output
20
RESETMAIN
Digital I/O
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
AGND
3.3 V STBY
DAC
V
REF
D1–/NTESTIN
D1+
D2–/A
IN9
D2+/A
IN8
V
BAT
+5 V
IN
−12
V
IN
+12 V
IN
+V
CCP
A
IN7
A
IN6
A
IN5
A
IN4
A
IN3
A
IN2
A
IN1
A
IN0
GPIO16/THERM
GPIO15
GPIO14
GPIO13
GPIO12
GPIO11
GPIO10
Ground
Power Supply
Analog Output
Analog Output
Analog Input
Analog Input
Programmable
Programmable
Analog Input
Analog Input
Analog Input
Analog Input
Analog Input
Analog Input
Analog Input
Analog Input
Analog Input
Analog Input
Analog Input
Analog Input
Analog Input
Digital I/O
Digital I/O
Digital I/O
Digital I/O
Digital I/O
Digital I/O
Digital I/O
1
GPIO pins are open drain and require external pull-up resistors. Fan inputs have integrated 10 kΩ pull-ups, but these pins become open drain when reconfigured as
GPIOs.
Rev. A | Page 7 of 56
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