The TPS3823-xx-Q1 can be used to monitor the supply rail for devices such as microcontrollers. The downstream device is enabled by the TPS3823-xx-Q1 once the voltage on the supply pin (VDD) is above the internal threshold voltage (VIT– + VHYS). The downstream device is disabled by the TPS3823-xx-Q1 when VDD falls below the threshold voltage minus the hysteresis voltage (VIT–). The TPS3823-xx-Q1 also issues a reset signal if the WDI input is not periodically triggered by a positive or negative transition at WDI. When the supervising system fails to retrigger the watchdog circuit within the time-out interval, ttout, RESET becomes active for the time period td.
Some applications require a shorter reset signal than the 200 ms that most of the TPS382x-xx-Q1 family provide. In these cases, the TPS3820-xx-Q1is a good choice because it has a delay time of only 25 ms. If an open-drain output is needed, replace the TPS3823-xx-Q1 with the TPS3828-xx-Q1 (if the WDI input must be active while RESET is low, see Decoupling WDI During Reset Event). Figure 9 shows the TPS3823-33-Q1 in a typical application.