SN74AVCH16T245: continuous current through VCC

pascal lassave

Part Number: SN74AVCH16T245
Other Parts Discussed in Thread: SN74LVCH16T245-EP, SN74LVC16T245, SN74AVC16T245,

Tool/software:

Component Ti : SN74AVCH16T245GR et SN74LVCH16T245-EP :

On one of our designs we performed stress analysis on contations cases between the SN74AVC16T245 or SN74LVC16T245 output and bidirectional FPGA IOs .

This contentation is a transient with a duration = ~2ms

- The result of our stress analysis shows that the IOs output current = 24mA
- There is no stress at IO level < ± 50mA define in Absolute max rating value

But on one SN74AVCH16T245 we have simultaneous contention on 7 IOs with a total current on VCCB rail = 121mA

The VCCA/VCCB/GND Absolute max rating value is given for continuous current (100mA) . It is possible to have information about transient current Absolut Max rating values ?

5 months ago

0 Clemens Ladisch 5 months ago

Guru 316410 points

There are no transient ratings. The 100 mA limit most not be exceeded, not even for a short time.

Can such bus contention actually happen? If yes, then you must protect against it with something like current-limiting resistors.

0 pascal lassave 5 months ago in reply to Clemens Ladisch

Prodigy 60 points

thanks.

Isn’t it a thermal phenomena ? Does it help if we can’t guarantee that it only happens at Ta=Tj=25°C ?

0 Clemens Ladisch 5 months ago in reply to pascal lassave

Guru 316410 points

When there is too much power dissipation in a small spot, the temperature of the rest of the die does not matter.

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SN74AVCH16T245: continuous current through VCC