SBASAD0A March 2022 – July 2022 AMC23C10
PRODUCTION DATA
In AC power-switching applications, closing the load switch during the zero-crossing of the AC line voltage minimizes the inrush current during turn-on. Figure 8-1 shows the implementation of a solid-state relay based on the TPSI3050-Q1 device. The TPSI3050-Q1 is an isolated switch driver with an integrated 10-V gate supply. The two external, back-to-back, n-type field effect transistor (NMOS) power switches are turned on when the EN pin of the TPSI3050-Q1 is driven high and are turned off when the EN pin is low. The AMC23C10 is used in this application to detect the zero crossing of the AC line voltage and to gate the EN signal to the TPSI3050-Q1. The high-side of the AMC23C10 is powered from the integrated 10-V gate drive supply of the TPSI3050-Q1 and does not require a separate power supply for the high-side.
The AC line voltage is clamped by R5 and two small-signal, antiparallel diodes to limit the voltage at the input of the AMC23C10. Close to the zero crossing of the AC line voltage, neither one of the diodes conduct and the voltage at the INP pin equals the AC line voltage. As illustrated in Figure 8-2, OUT1 (an open-drain output) toggles from high-to-low during the rising zero-crossing event and from low-to-high during the falling zero-crossing event. OUT2 (a push-pull output) toggles with the opposite polarity and can be used in a discrete logic block or my a microcontroller to gate the EN signal of the TPSI3050-Q1.