Rainbow Electronics LM87 - Manual (Page 3)

Pin Description
(Continued)
Pin
Name(s)
Pin
Number
Number
of Pins
Type Description
GND 8 1 GROUND The system ground pin. 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.
V + (+2.8 V to
+3.8 V)
9 1 POWER +3.3 V V + power. Bypass with the parallel combination of 10 µF
(electrolytic or tantalum) and 0.1 µF (ceramic) bypass capacitors.
INT# /ALERT# 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. It has an on-chip 100 k Ω pullup resistor. Alternately used
as an active low output to signal SMBus Alert Response Protocol.
DACOut/NTEST_IN 11 1 Analog
Output/Digital
Input
0 V to +2.5 V amplitude 8-bit DAC output. When forced high on
power up by an external voltage the NAND Tree Test mode is
enabled which provides board-level connectivity 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 also acts as an active low power on
RESET input. It has an on-chip 100 k Ω pullup resistor.
D1− 13 1 Analog Input Analog input for monitoring the cathode of the first external
temperature sensing diode.
D1+ 14 1 Analog Input Analog input for monitoring the anode of the first external
temperature sensing diode.
+12Vin 15 1 Analog Input Analog input for monitoring +12 V.
+5Vin 16 1 Analog Input Analog input for monitoring +5 V.
Vccp2/D2− 17 1 Analog Input Digitally programmable analog input for monitoring Vccp2 (0 to 3.6
V input range) or the cathode of the second external temperature
sensing diode.
+2.5Vin/D2+ 18 1 Analog Input Digitally programmable analog input for monitoring +2.5 V or the
anode of the second external temperature sensing diode.
Vccp1 19 1 Analog Input Analog input (0 to 3.6 V input range) for monitoring Vccp1, the core
voltage of processore 1.
VID4/IRQ4-
VID0/IRQ0
20-24 5 Digital Inputs Digitally programmable dual function digital inputs. Can be
programmed to monitor the VID pins of the Pentium/PRO and
Pentium II processors, that indicate the operating voltage of the
processor, or as interrupt inputs. The values are read in the
VID/Fan Divisor Register and the VID4 Register. These inputs have
on-chip 100 k Ω pullup resistors.
TOTAL PINS 24
# Indicates Active Low (“Not”)
LM87
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