5.8.3 Alert Output Configuration

The Alert output can be enabled by using bit 3 of the CONFIG register (Alert Output Control bit) and can be configured as either a comparator output or as an Interrupt Output mode using bit 0 of CONFIG (Alert Output Mode bit). The polarity can also be specified as active-high or active-low using bit 1 of CONFIG (Alert Polarity bit). This is an open-drain output and requires a pull-up resistor.

When the ambient temperature increases above the critical temperature limit, the Alert output is forced to a comparator output (regardless of CONFIG<0>). When the temperature drifts below the critical temperature limit minus hysteresis, the Alert output automatically returns to the state specified by CONFIG<0> bit.

Figure 5-9. Active-Low Alert Output Configuration.

The status of the Alert output can be read using CONFIG<4> (Alert Output Status bit). This bit can not be set to ‘1’ in Shutdown mode.

Bits 7 and 6 of the CONFIG register can be used to lock the TUPPER, TLOWER and TCRIT registers. These bits prevent false triggers at the Alert output due to an accidental rewrite to these registers.

The Alert output can also be used as a critical temperature output using bit 2 of CONFIG (Alert Output Select bit). When this feature is selected, the Alert output becomes a comparator output. In this mode, the interrupt output configuration (Alert Output Mode bit, CONFIG<0>) is ignored.