8.6.5 Configuration Register 1

The Configuration Register 1 sets the temperature range, controls shutdown mode, and determines how the ALERT/THERM2 pin functions. The Configuration Register is set by writing to pointer address 09h and read by reading from pointer address 03h.

The MASK bit (bit 7) enables or disables the ALERT pin output if ALERT/THERM = 0. If ALERT/THERM = 1, then the MASK bit has no effect. If MASK is set to ‘0’, the ALERT pin goes low when one of the temperature measurement channels exceeds its high or low limits for the chosen number of consecutive conversions. If the MASK bit is set to 1, the TMP43x will retain the ALERT pin status, but the ALERT pin does not go low. This happens immediately regardless of mode of operation.

The shutdown (SD) bit (bit 6) enables or disables the temperature measurement circuitry. lf SD = 0, the TMP43x convert continuously at the rate set in the conversion rate register. When SD is set to 1, the TMP43x immediately stop converting and enter a shutdown mode. When SD is set to 0 again, the TMP43x resume continuous conversions. A single conversion can be started when SD = 1 by writing to the One-Shot Register.

The AL/TH bit (bit 5) controls whether the ALERT pin functions in ALERT mode or THERM2 mode. If AL/TH = 0, the ALERT pin operates as an interrupt pin. In this mode, the ALERT pin goes low after the set number of consecutive out-of-limit temperature measurements occur.

If AL/TH = 1, the ALERT/THERM2 pin implements a THERM function (THERM2). In this mode, THERM2 functions similar to the THERM pin except that the local high limit and remote high limit registers are used for the thresholds. THERM2 goes low when either RHIGH or LHIGH is set.

The temperature range is set by configuring bit 2 of the Configuration Register 1. Setting this bit low configures the TMP43x for the standard measurement range (0°C to 127°C); temperature conversions will be stored in the standard binary format. Setting bit 2 high configures the TMP43x for the extended measurement range (–64°C to 191°C); temperature conversions are stored in the extended binary format (see Table 1).

The remaining bits of the Configuration Register 1 are reserved and must always be set to 0. The power-on reset value for this register is 00h. Table 7 summarizes the bits of the Configuration Register 1.