Other Parts Discussed in Thread: BQ24253
Hello,
I need to run TS3USB221 from an 'always on' supply for a battery powered device. The 'always on' power is BQ24253 SYS output, i.e., single Li-ion battery. The TS3USB221 needs to be able to switch between BQ24253 D+/D- pins and a USB PHY.
Presently, I have Vcc connected to a resistor divider, 10kΩ/86.6kΩ, with the top side connected to BQ24253's SYS load (single-cell Li-ion). The S pin is connected to a separate resistor divider 10kΩ/10kΩ to the /PG pin of BQ24253, with the top side connected to BQ24253's LDO pin. Based on my calculations, a fully charged battery will cause Vcc to be slightly (~0.3V) above the recommended voltage of 3.6V, which is well below the absolute maximum rating. The S pin logic appears to have no problems with meeting needed thresholds for the variable Vcc.
Is this ok? It seems very wasteful (power and $) to put a dedicated SMPS in just for this simple switch.
Best Regards,
David
