7.4.2 S3 and Pseudo-S5 Support

The TPS51200 provides S3 support by an EN function. The EN pin could be connected to an SLP_S3 signal in the end application. Both REFOUT and VO are on when EN = high (S0 state). REFOUT is maintained while VO is turned off and discharged via an internal discharge MOSFET when EN = low (S3 state). When EN = low and the REFIN voltage is less than 0.390 V, TPS51200 enters pseudo-S5 state. Both VO and REFOUT outputs are turned off and discharged to GND through internal MOSFETs when pseudo-S5 support is engaged (S4 or S5 state). Figure 19 shows a typical start-up and shutdown timing diagram for an application that uses S3 and pseudo-S5 support.