MON35W42 datasheet(18/60 Pages) SMSC

18 / 60 page

The other negative voltage input V6 (approximate -5V) also can be evaluated by a similar method and

the series resistors can be selected as R7=120K ohms and R8=56K ohms. The equation for a V6 of -

5V voltage is as follows.

NVIN

VREF

Where

. is 120K/(120K+56K). If the monitored ADC value in the N5VIN channel is 0.8635,

VREF=3.6V and the parameter

. is 0.6818 then the negative voltage of V6 can be -5V.

Monitor temperature from thermistor:

The MON35W42 can connect to three thermistors to measure three different environment

temperatures. The specification of thermistor is: (1)

- value is 3435K, (2) resistor value is 10K ohms at

%C. In Figure 11, the themistor is connected by a series resistor to a 10K Ohms resistor, then to

VREF (Pin 37).

Monitor temperature from Pentium

® II thermal diode or bipolar transistor 2N3904

The MON35W42 can monitor the temperature from the Pentium

® II (Deschutes) thermal diode interface

or a 2N3904 transistor. The circuit is shown in Figure 12. The Pentium

® II D- pin is connected to power

supply ground (GND) and the D+ pin is connected to pin PIITDx in the MON35W42. The resistor

R=30K ohms is connected to VREF to supply the diode bias current and the bypass capacitor

C=3300pF is used to filter the high frequency noise. The transistor 2N3904 is to a form a diode, the

Base (B) and Collector (C) in the 2N3904 are tied together to act as a thermal diode.

MON35W42 Datasheet(PDF) 18 Page - SMSC Corporation