F71869F datasheet(21/116 Pages) FINTEK

21 / 116 page

Fintek

Feature Integration Technology Inc.

2009

V1.1

F71869

127°C

1111 1111

Open

1000 0000

5.2.2 Monitor Temperature from “Thermistor”

The F71869 can connect three thermistors to measure environment temperature or remote

temperature. The specification of thermistor should be considered to (1)

β value is 3435K (2) resistor

value is 10K ohm at 25

°C. In the Figure 2, the thermistor is connected by a serial resistor with 10K ohm,

then being connected to VREF.

5.2.3 Monitor Temperature from “Thermal diode”

Also, if the CPU, GPU or external circuits provide thermal diode for temperature measurement, the

F71869 is capable to these situations. The build-in reference table is for PNP 2N3906 transistor. In the

Figure 2, the transistor is directly connected into temperature pins.

5.2.4 ADC Noise Filtering

The ADC is integrating type with inherently good noise rejection. Micro-power operation places

constraints on high-frequency noise rejection; therefore, careful PCB board layout and suitable

external filtering are required for high-accuracy remote measurement in electronically noisy

environment. High frequency EMI is best filtered at D+ and D- with an external 2200pF capacitor. Too

high capacitance may introduce errors due to the rise time of the switched current source. Nearly all

noise sources tested cause the ADC measurement to be higher than the actual temperature,

depending on the frequency and amplitude.

5.2.5 Monitor Temperature from “SMBus device”

F71869 provides SMBus block read/write compatible Platform Control Hub (PCH) EC SMBus

protocol, and provides byte read/write protocol to read CPU and chipset thermal temperature

information. For byte read /write protocol, F71869 supports 4-suit device address to read or write

from device information. For block read/write, F71869 support 1 suits device address and maximum 17

byte count for read protocol to read from device information, and 4 byte count for write protocol to write

information to device.

5.2.6 Monitor Temperature from “PECI”

F71869 support Intel PECI1.1/PECI_Request/PECI_Available interfaces to read temperature from

PECI 1.1 device.

F71869F Datasheet(PDF) 21 Page - Feature Integration Technology Inc.