SN55HVD75-EP: Driver / receiver enable times when driven together

Benjamin Buck

Part Number: SN55HVD75-EP

I am using a SN55HVD75-EP in my design, and I have a question about the Driver / receiver enable times.

Section 6.6 of the datasheet lists the driver enable time under two different test conditions, with the receiver enabled and with the receiver disabled. Similarly, the datasheet lists the receiver enable time under two different test conditions, with the driver enabled and with the driver disabled.

In my design I will by tying the driver enable pin and the receiver enable pin to the same net, so when the device is switching from driver enabled to driver disabled it will simultaneously be switching from receiver disabled to receiver enabled.

My question is: which driver / receiver enable time applies in this situation?

over 4 years ago

0 Eric Hackett over 4 years ago

TI__Guru 74252 points

Benjamin,

Thanks for bringing this to E2E. You would use the driver/receiver disabled times listed in the datasheet.

Regards,

Eric Hackett

0 Benjamin Buck over 4 years ago in reply to Eric Hackett

Prodigy 10 points

Thanks for the reply. One of the suggested topics deals with a similar part, but came to the opposite conclusion, that I should use the driver/receiver _enabled_ times. (link) https://e2e.ti.com/support/interface-group/interface/f/interface-forum/279139/sn65hvd72-driver-enable-time-when-de-and-re-are-tied-together

Are the 75 and 72 parts different in their behavior?

0 Eric Hackett over 4 years ago in reply to Benjamin Buck

TI__Guru 74252 points

Benjamin,

Good catch, and this is something I was debating myself before I answered this question: if the state of the receiver/driver had to be set before the "delay state" could be considered. It looks as though I was incorrect in my initial assessment, the 75 and 72 parts should behave the same way, so ignore my first answer. Go ahead and used the enabled times.

Regards,

Eric Hackett

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SN55HVD75-EP: Driver / receiver enable times when driven together