TMP108 datasheet(10/19 Pages) TI

10 / 19 page

TMP108

SBOS663 – APRIL 2013

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HIGH- AND LOW-LIMIT REGISTERS

In comparator mode (TM = '0'), the ALERT pin becomes active when the temperature exceeds the value in the

THIGH register or drops below the value in the TLOW register. The ALERT pin remains active until the temperature

returns to a value that is within the range set by:

(TLOW + HYS) and (THIGH – HYS)

where

•

HYS is the hysteresis set by the hysteresis control bits (HYS1 and HYS0).

(1)

In interrupt mode (TM = '1'), the ALERT pin becomes active when the temperature exceeds the value in the

THIGH register or drops below the value in the TLOW register, and remains active until a read operation of the

configuration register occurs (also clears the values latched in the watchdog flags, FL and FH), or the device

successfully responds to the SMBus alert response address. The ALERT pin is also cleared by resetting the

device with the general call reset command.

Both operational modes are represented in Figure 10 and Figure 11.

Table 9 and Table 10 describe the format for the THIGH and TLOW registers. Note that the most significant byte is

sent first, followed by the least significant byte. Power-up (reset) default values are THIGH = +127.9375°C and

TLOW = –128°C. These values ensure that upon power-up, the limit window is set to maximum, and the ALERT

pin does not become active until the desired limit values are programmed in the registers. Other default values

for the temperature limits are availlable by request. The format of the data for THIGH and TLOW is the same as for

the temperature register.

Table 9. Bytes 1 and 2 of THIGH Register

BYTE

H11

H10

BYTE

Table 10. Bytes 1 and 2 of TLOW Register

BYTE

L11

L10

BYTE

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