f75367 Feature Integration Technology Inc., f75367 Datasheet - Page 10

• Manufacturer Part Number: f75367
• Description: Temperature Sensor With I2c-sst Bridge
• Manufacturer: Feature Integration Technology Inc.

6.4 SST Master
6.5 PCB Layout Guide
measurement. For example, 15% variation in beta for two forced IE currents and the beta is 0.5 would
contribute about 11.12℃ error per 100℃.
In Order to solve the second issue, the F75367 provides a beta compensation solution for accurate
temperature sensing. The F75367 can support the beta range over 0.2 for beta compensation. In this
new method, the F75367 will provide two IE currents, and feedback two IB currents. The F75367 will
auto-adjust IE (IE1 and IE2) current and feedback IB (IB1 and IB2) promptly for getting proper IC
proportion (IC1/ IC2), then calculates the accurate temperature. This algorithm of beta compensation is
suitable for substrate transistor or new generational CPU (i.e. 45nm CPU) because small beta and high
proportional beta variation.
F75367 Support 6 external device inputs for temperature reading by SST and pass to host by I2C. It’s
really a SST to I2C bridge IC for some specific SST temperature sensors’ application. User can ready
SST temperature sensor by F75367 bridge function. For instance, user would like to read an external
SST temperature sensor by F75367. She could follow below list to read the SST Device Temperature.
Totally the F75367 can support 6 external device inputs by SST master. About the detail setting of register,
please refer the register description.
PCB can be electrically noisy environments, and the F75367 is measuring very small voltage from the
remote sensor, so care must be taken to minimize noise which is occurred at the sensor inputs. The
following guideline should be taken to reduce the measurement error of the temperature sensors:
Place the F75367 as close as practical to the remote sensing diode. In noisy environments, such as a
computer main-board, the distance can be 4 to 8 inches. (typ). This length can be increased if the worst
noise sources are avoided. Noise sources generally include clock generators, CRTs, memory buses and
PCI/ISA bus etc.
Route the D+ and D- tracks close together, in parallel, with grounded guard tracks on each side. Provide
If the address/index of SST device is 49h/00h.Before you read the temperature from SST
device. You should do below list:
1.
2.
3.
4. read register 78h to get the temperature value of SST device
write 00h to register 48h (Define external device0 index)
write “1” to register 50h bit 0 (Enable external device0)
write register 49h to register 40h (Define external device0 address)
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F75367
Feb..
V0.11P
, 2008