LM94 datasheet(7/24 Pages) NSC

7 / 24 page

9.0 Pin Descriptions (Continued)

Symbol

Pin #

Type

Function

AD_IN11

Analog Input

(SCSI_Core)

Analog input for +2.5V monitoring, nominal 3⁄4 scale reading. This

pin may also be used to monitor an analog temperature sensor such

as the LM60, since readings from this input can be routed to the fan

control logic.

AD_IN12

Analog Input

(Mem_Core)

Analog input for +1.969V monitoring, nominal 3⁄4 scale reading.

AD_IN13

Analog Input

(Mem_Vtt)

Analog input for +0.984V monitoring, nominal 3⁄4 scale reading.

AD_IN14

Analog Input

(Gbit_Core)

Analog input for +0.984V S/B monitoring, nominal 3⁄4 scale reading.

AD_IN15

Analog Input (-12V)

Analog input for -12V monitoring. External resistors required to scale

to positive level. Full scale reading at 1.236V, , nominal 3⁄4 scale

reading. This pin may also be used to monitor an analog

temperature sensor such as the LM60, since readings from this

input can be routed to the fan control logic.

Address Select

3 level analog input

This input selects the lower two bits of the LM94 SMBus slave

address.

3.3V SB (AD_IN16)

POWER (V

DD) +3.3V

standby power

DD power input for LM94. Generally this is connected to +3.3V

standby power.

The LM94 can be powered by +3.3V if monitoring in low power

states is not required, but power should be applied to this input

before any other pins.

This pin also serves as the analog input to monitor the 3.3V

stand-by (SB) voltage. It is necessary to bypass this pin with a 0.1

µF in parallel with 100 pF. A bulk capacitance of 10 µF should be in

the near vicinity. The 100 pF should be closest to the power pin.

GND

GROUND

Digital Ground. Digital ground and analog ground need to be tied

together at the chip then both taken to a low noise system ground.

A voltage difference between analog and digital ground may cause

erroneous results.

PWM1

Digital Output

(Open-Drain)

Fan control output 1.

PWM2

Digital Output

(Open-Drain)

Fan control output 2

P1_VID0/P1_VID7

Digital Input

Voltage Identification signal from the processor. Supports TTL input