Startup

Start of

Conversion

Delay

(1)

27 ms

Start of

Conversion

Delay

(1)

27 ms

27 ms

TMP108

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SBOS663 – APRIL 2013

Thermostat Mode (TM)

The thermostat mode bit indicates to the device whether to operate in comparator mode (TM = '0') or interrupt

mode (TM = '1', default). For more information on comparator and interrupt modes, see the High- and Low-Limit

Registers section.

Temperature Watchdog Flags (FL and FH)

The TMP108 uses temperature watchdog flags in the configuration register that indicate the result of comparing

the device temperature at the end of every conversion to the values stored in the temperature limit registers

the flag-low bit (FL) is set to '1'. If both flag bits remain '0', then the temperature is within the temperature range

set by the temperature limit registers. In interrupt mode, when any of the flags is set by an under- or

overtemperature event, the SMBus ALERT Response only clears the pin and not the flags. Reading the

configuration register clears both the flags and the pin.

Conversion Rate

The conversion rate bits, CR1 and CR0, configure the TMP108 for conversion rates of 0.25 Hz, 1 Hz, 4 Hz, or 16

Hz. The default rate is 1 Hz. The TMP108 has a typical conversion time of 27 ms. To achieve different

conversion rates, the TMP108 makes a conversion, and then powers down and waits for the appropriate delay

set by CR1 and CR0. Table 8 shows the settings for CR1 and CR0.

Table 8. Conversion Rate Settings

CR1

CR0

CONVERSION RATE

0

0

0.25 Hz

1

μA

0

1

1 Hz (default)

2

μA

1

0

4 Hz

5

μA

1

1

16 Hz

18

μA

After power-up or a general-call reset, the TMP108 immediately starts a conversion, as shown in Figure 9. The

first result is available after 27 ms (typical). The active quiescent current during conversion is 40

μA (typical at

+25°C). The quiescent current during delay is 0.7

μA (typical at +25°C).

(1)

Delay is set by the CR1 and CR0 bits in the configuration register.

Figure 9. Conversion Start

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