Rainbow Electronics LM81 - Manual (Page 4)

Pin Description
(Continued)
Pin
Name(s)
Pin
Number
Number
of Pins
Type Description
INT 10 1 Digital Output Interrupt active low open-drain output. This output is enabled when
Bit 1 in the Configuration Register is set to 1. The default state is
disabled.
DACOut/NTEST_IN 11 1 Analog
Output/Digital
Input 0V to +1.25V amplitude 8-bit DAC output. When forced high by an
external voltage the NAND Tree Test mode is enabled which
provides board-level connectivity testing. Refer to Section 11.0 on
NAND Tree testing.
RESET 12 1 Digital I/O Master Reset, 5 mA driver (open-drain), active low output with a
20 ms minimum pulse width. Available when enabled via Bit 4 in
the Configuration register. It acts as an active low power on
RESET input.
GND 13 1 GROUND Internally connected to all circuitry. The ground reference for all
analog inputs and the DAC output. This pin needs to be
connected to a low noise analog ground plane for optimum
performance of the DAC output.
Vccp2 14 1 Analog Input Analog input for monitoring −12V or Vccp2. Selectable by
choosing the appropriate external resistor divider values such that
the input to the LM81 is scaled to +2.5V. See
Section 4.0.
+12Vin 15 1 Analog Input Analog input for monitoring +12V.
+5Vin 16 1 Analog Input Analog input for monitoring +5V.
+3.3Vin 17 1 Analog Input Analog input for monitoring +3.3V.
+2.5Vin 18 1 Analog Input Analog input for monitoring +2.5V.
Vccp1 19 1 Analog Input Analog input for monitoring Vccp, a processor voltage that is
nominally at +2.5V.
VID4-VID0 20-24 5 Digital Inputs Supply Voltage readouts from the Pentium/PRO power supplies
that indicate the operating voltage or the processor (e.g. 1.5V to
2.9V). The values are read in the VID/Fan Divisor Register and
the VID4 Register.
TOTAL PINS 24
LM81
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