W83L785R Datasheet, PDF (13/38 Pages) Winbond – WINBOND H/W MONITORING IC FOR NOTEBOOK

W83L785R/W83L785G
6.5.1 Monitor temperature from thermistor:
The W83L785R/G can connect two thermistors to measure three different environment temperature or
remote temperature. The specification of thermistor should be considered to (1) β value is 3435K, (2)
resistor value is 10K ohms at 25°C. In the Figure 3, the themistor is connected by a serial resistor with
10K Ohms, and then connected to VREF (pin 17).
6.5.2 Monitor temperature from Pentium IITM thermal diode
The W83L785R/G can alternate the thermistor to Pentium II^TM (Deschutes) thermal diode interface
and the circuit connection is shown as Figure 4. The pin of Pentium II^TM D- is connected to power
supply ground (GND) and the pin D+ is connected to pin PIIx in the W83L785R/G. The resistor R=15K
ohms should be connected to VREF to supply the diode bias current and the bypass capacitor
C=3300pF should be added to filter the high frequency noise.
Pentium II/III
CPU
D+
Therminal
Diode
D-
Pentium II/III
CPU
D+
Therminal
Diode
D-
R=15K, 1%
R=15K, 1%
C=3300pF
VREF
PIITDx
W83L785R
C=3300pF
PIITDx
Figure 4.
6.5.3 Over Temperature signal (OVT#)
W83L785R/G provides two external thermal sensors to detect temperature. When detected
temperature exceeds the over-temperature value, pin OVT# will be asserted until the temperature
goes below the hysteresis temperature. Pin OVT# has 2 operating modes.
6.5.3.1. Comparator Mode:
At this mode, temperature exceeding T_O causes the OVT# output activated until the temperature is
less than T_HYST. (Figure 5)
Publication Release Date: Apr. 2006
-9-
Revision 1.1