TPS54302: 12VDC in to -12VDC and +5VDC

Hi,

The bead can't be used as an inductor.

Shawn

The input capacitor on the -12V supply should be referenced to the -12VCC (gnd pin of device) output.

The enable resistors may need a different connection, see  http://www.ti.com/lit/an/slva540/slva540.pdf

Can you please elaborate?

David,

   In regards to the enable pin resistors, are you referring to the 12V to -12V supply or the 5V? After reviewing the document you sent out, I see that the voltage divider should be referenced to the -12V, not the ground. Copied directly from the document is the script below.

Note, the divider must still ensure that the EN pin does not exceed the maximum pin rating of 5 V (which will be –7 V with a –12 V reference). In this case, the voltage divider in Figure 3 is modified to be referenced to –12 V. The following EN equation is derived from Figure 4.

Thanks for your time.

Hi,

Any other question?

Shawn

David,

   In regards to the enable pin resistors, are you referring to the 12V to -12V supply or the 5V? After reviewing the document you sent out, I see that the voltage divider should be referenced to the -12V, not the ground. Copied directly from the document is the script below.

Note, the divider must still ensure that the EN pin does not exceed the maximum pin rating of 5 V (which will be –7 V with a –12 V reference). In this case, the voltage divider in Figure 3 is modified to be referenced to –12 V. The following EN equation is derived from Figure 4.

Thanks for your time.

I've attached an updated schematic with some questions regarding the ground and -12V reference. Please look it over and let us know your thoughts.

Power 125-12 TPS54302 A1.pdf