SN74AVC4T245: power down issue

Dane Zhang

Part Number: SN74AVC4T245

Hi team，

Our customer is now testing SN74AVC4T245 and they found that when power down, the 1.8V supply will have a peak as shown in the pic. Could you help to confirm will the supply peak affect the buffer? will this lead to a reliability risk in long term?

Thanks!

over 3 years ago

0 Emrys Maier over 3 years ago

TI__Guru* 96591 points

Hi Dane,

I think we're missing some important information.

I get that this is a 1.8V supply rail, and the thread title indicates that you're having a "power down issue" -- but other than that, I don't really know what the trouble is.

First, can you provide a schematic?

Next, can you describe the issue you are having?

If you are actually asking if this supply curve will be a problem for our device, can you tell me what the other supply pin is doing during this time? What about the input pins? Are the outputs connected to any active circuitry?

0 Dane Zhang over 3 years ago in reply to Emrys Maier

TI__Expert 3420 points

Hi Emrys,

SCH is as below, the C2D_SLMAP_XX signal is from FPGA, which is 1.8V and VDD_CTRL_1.8V is the supply.

Now find that when power down. The power supply will have a peak during power ramp down. Will the peak lead to a reliability risk in long term？

Thanks！

0 Emrys Maier over 3 years ago in reply to Dane Zhang

TI__Guru* 96591 points

Hi Dane,

It looks like you just have the same image posted twice more.

0 Dane Zhang over 3 years ago in reply to Emrys Maier

TI__Expert 3420 points

Hi Emrys,

Sorry, pls see the SCH pic

0 Emrys Maier over 3 years ago in reply to Dane Zhang

TI__Guru* 96591 points

Thanks Dane,

That helps a great deal.

With this configuration I don't see any danger of reducing the lifetime of the device with that supply waveform. The voltage never goes outside the recommended operating range.

The buffer could be active when the supply comes back up, but that most likely won't cause any problems. The only case I could think of where it might be an issue is if something else is on the same bus and also turns on at the same time causing bus contention.

0 Dane Zhang over 3 years ago in reply to Emrys Maier

TI__Expert 3420 points

Emrys,

Thanks a lot for your confirmation！

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SN74AVC4T245: power down issue