TPS57040-Q1: About TPS57040-Q1 operation in Vsense and RCLK resistor open condition

1.VSWNSE resistor (RA) open condition
　 Please tell me the operation of TPS57040-Q1 under these conditions.
YZ: If RA is open, VSENSE has no information of Vout. The feedback loop will try its best to drive Vout up, as a negative feedback loop should do. Then you will see Vout being driven to close to Vin. Your load might be damaged if they are not rated upto Vin voltage level.

2.VSWNSE resistor (RB) open condition
　 Please tell me the operation of TPS57040-Q1 under these conditions.
YZ: If RB is open and RA is connected, VSENSE = VOUT. The control loop always regulate VSENSE to 0.8V, so VOUT will be regulated to 0.8V as well. If both RA and RB are open, it will be the same as RA open condition in '1'.

3.RCLK resistor open condition
Please tell me the operation of TPS57040-Q1 under these conditions.
YZ: The oscillator will not work properly is RCLK is open or short. The frequency is set by the current of an internal voltage source applying VRT to the RT pin. Current seen by the pin: VRT/RCLK set the frequency. Vout will not be regulated if RCLK is open.

Hope these helps,

Yang