TPS4811-Q1: while TPS48111-Q1 works alone without MCU, can user send the INP_G and INP pulling up signal asynchronously

Hank,

The CD40194B is a bi-directional shift register that has "NO RECOMMENDED FOR NEW DESIGNS" on the datasheet- so I would say this would not be advisable to use. 

It would be hard to do this without an MCU, but to stagger two GPIO signals derived from a 48V rail so they go low at different times, one way would be to use two N-channel MOSFETs with an RC delay network on the gate of the second one. Each GPIO is pulled up to 48V and pulled low through its respective FET. The first FET gate is driven directly by the 48V signal, allowing it to turn on immediately. The second FET gate is connected to the same control signal, but with a resistor and capacitor (RC network) in series, introducing a delay in its turn-on time. The delay can be set using the formula t ≈ 0.7 × R × C. For example, using a 100kΩ resistor and a 0.1 μF capacitor would give a delay of about 7 milliseconds. 

Best Regards,
Tim 

Hank,

This would theoretically work- but the timings and capacitances might be a bit tricky. The logic level high for this device has a maximum of 2V. You essentially have to size the capacitor so that the INP_G pin does not start charging until the INP pin hits 2V.... which might make startup a bit unpredictable with timing.

Best Regards,
Tim