TPS54240: TPS54240 split rail short circuit behavior

Hi Kai,

Do you mean the VONEG is generated from auxiliary winding on buck conversion inductor?

1. VOPOS shorts to GND--------Operating at lowest duty cycle with Fsw decrease to about 17% of normal operation freq, 

2. VONEG shorts to GND--------Depends on the load condition of VOPOS, Fsw decrease to certain % of normal operation freq, high risk to damage the IC if actual freq is not decreased to lowest level.

3. VOPOS/VONEG shorts to GND---------Operating at lowest duty cycle with Fsw decrease to about 17% of normal operation freq, 

B R

Andy

Hi Andy,

The split rail power supply schematic is referred from datasheet 8.2.3 TPS54240 Split rail power supply.
The VONEG is generated from TPS54240 GND and VOPOS is generated from auxiliary winding.

Regards,
Kai

Hi Andy,

Thank you for your comment.

btw, back to the first question, Based on Figure 63, if there is short event like VOPOS shorts to GND/VONEG shorts to GND/ VOPOS and VONEG short to GND, how does TPS54240 behave?
1. VOPOS shorts to GND
2. VONEG shorts to GND
3. VOPOS/VONEG shorts to GND

Regards,
Kai

Hi Kai,

Pls advise the load current of VOPOS and VONEG. 

B R

Andy

Hi Andy,

The max output current is +/-0.4A.

Regards,

Kai

Hi Kai,

Based on Fig 63 circuit, VOPOS and VONEG are symmetrical outputs to share the inductor energy, so any output short to GND will cause Vsense decrease near zero, then IC operates at lowest duty cycle with Fsw decrease to about 17% of normal operation freq, and inductor DC current is limit to about IC current limiting.

B R

Andy