LM27402: device marking and EN demo,power up fail

1. The different numbers refers to batch codes. I have responded to Shawn on similar issue and have requested to try out a change.

2. evm schematic attached. The EN resistors are open and there is an internal pull up to turn the part on.

Regards,

Mathew

Hi Mathew,

1.i know it refers to batch codes.Can you explain the what does VM04AE stand for?like date,factory?

2.With Ren1 and Ren2 open,the circuit works normall.But Vin(12V) is only 3V when  the output begins to rise.

In my design there are several lm27402,and now I use RC circuit on EN to delay lm27402 power up time,  due to power sequece requirement.

With Ren1(10K) and Ren2(2K) on,and Cen(100nF),the chip with "VM04AE" power up fail occasionally,and the chip with "VM09AD" works well.

So mostly there is diffence betteew the two batch causing this issue.Do you have any suggestion how to control EN to satisfy power up requirment?

Thanks

This case is a matter of urgency,plz hurry,thanks