TPS546D24A: Enable Timing

Allan Fan

Expert 7090 points

Part Number: TPS546D24A

Tool/software:

Hi expert,

Customer used TPS546D24A and find out the timing of Vo startup after enable is different in different boards.

The test was done with two top markings:

TPS546D24A TI 02I AV9V E4

TPS546D24A TI 31I AV8E E4

The top marking with 31I AV8E E4 has longer delay time about 3ms. Customer swap the chips and the symptom followed the chip.

Do you have any ideas why this might happened?

Regards,

Allan

11 months ago

0 Tomoya Ide 11 months ago

TI__Genius 11396 points

Hi Allan,

What are the differences between the two boards? Do they have the same schematic and PCB layout? Are they programmed differently, like with the TON_DELAY?

Thank you,
Tomoya

0 Allan Fan 11 months ago in reply to Tomoya Ide

TI__Expert 7090 points

Hi Tomoya,

The two boards are the same. The only difference is just the IC was built in different lots.

Regards,

Allan

0 Tomoya Ide 11 months ago in reply to Allan Fan

TI__Genius 11396 points

Hi Allan,

What they are seeing is the delay that happens when the device powers on (the delay is from AVIN rising to the part enabling the EN function). During this time, the device reads its memory, detects programming resistors, and sets itself up before it can respond to the Enable pin. Different parts may have different startup delays. Usually, it takes about 8 to 12 milliseconds for the device to respond to the Enable pin, and that is why they are seeing an EN to Vout rise delay longer than TON_DELAY and greater part-to-part variation.

Thank you,
Tomoya