TPSF12C1: IGND connection

Hirotsugu Kobayashi

Part Number: TPSF12C1

Hi team, I have three questions.

1. There is an instruction to connect IGND and REF GND to Chasis (PE).
In this case, it need to connect the 12V output of the secondary side with PELV connection to VDD.
What should I do if I only have SELV output and no PELV output?

2. I think the specification is to use a sense/injection capacitor to provide insulation between the primary and secondary, is that correct?

3. Should the connection between IGND and PE be made from the PE closest to the AC input (near the Y connector)?

Best Regards,

9 months ago

0 Timothy Hegarty 9 months ago

TI__Guru 60937 points

Hi Kobayashi-san,

1. Yes the IGND and REFGND pins should be connected at the IC. Then this connects to chassis GND with a low parasitic inductance connection, as it is the main conduction path for inject cap current to ground. In terms of supplying bias to the IC, recommendation is to route the supply lines and maintain spacing as needed.

2. The sense and inject caps should be Y-rated, just like a normal Y capacitor.

3. Yes, the IC GND connection to PE should be made where the normal Y-caps would connect. This is typically to the chassis, which is then connected to PE. Note that the regulator-side Y-caps are typically closer to the power stage and provide the first line of defense (filtering) for CM currents, so their GND can be closer to the power stage if this is possible in the layout. Otherwise, one central grounding point for the filter circuit is also acceptable.

Regards,

Tim