EMC1187 datasheet(37/47 Pages) MICROCHIP

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Triple Channel 1°C Temperature Sensor with Hardware Thermal Shutdown and 1.8V SMBus Communications

Datasheet

SMSC EMC1187

Revision 1.0 (07-11-13)

DATASHEET

6.14

Beta Configuration Registers 25h and 26h

This register is used to set the Beta Compensation factor that is used for External Diode 2s.

External Diode 2.



‘0’ - The Beta Compensation Factor auto-detection circuitry is disabled.



‘1’ (default) - The Beta Compensation factor auto-detection circuitry is enabled. At the beginning of

every conversion, the optimal Beta Compensation factor setting will be determined and applied.

The BETA2X[2:0] bits will be automatically updated to indicate the current setting. This is the

default for EMC1187

Bit 2-0 - BETA2[2:0] - These bits always reflect the current beta configuration settings. If auto-detection

circuitry is enabled, these bits will be updated automatically and writing to these bits will have no effect.

If the auto-detection circuitry is disabled, these bits will determine the beta configuration setting that is

used for the respective channels.Care should be taken when setting the BETA2[2:0] bits when the

auto-detection circuitry is disabled. If the Beta Compensation factor is set at a beta value that is higher

than the transistor beta, the circuit may introduce measurement errors. When measuring a discrete

thermal diode (such as 2N3904) or a CPU diode that functions like a discrete thermal diode (such as

an AMD processor diode), the BETA2[2:0] bits should be set to ‘111b’.

Table 6.15 Consecutive Alert / Therm Settings

NUMBER OF CONSECUTIVE OUT OF LIMIT

MEASUREMENTS

(default for CALRT[2:0])

(default for CTHRM[2:0])

Table 6.16 Beta Configuration Register

ADDR.

R/W

DEFAULT

26h

External

Diode 2 Beta

Configuration

ENABLE2

BETA2[2:0]

Table 6.17 CPU Beta Values

HEX

ENABLE2

BETA2[2:0]

MINIMUM BETA

0.11

0.18

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