LPC MicrocontrollersのトピックNVT2008 with pushpull outputs in both sides.

NVT2008 with pushpull outputs in both sides.

francobucafusco — Wed, 12 Sep 2018 11:14:03 GMT

Hi!

I have an implmementation doubt in regard the usage of this chip.

I have to interfaces a 3.3v domain (microcontroller) witha 5V domain (lcd).

From both sides I have pushpull outputs and hiz inputs.

Do I need pullup resistos on both sides or all the examples from the datasheet are targeting to opendrain outputs?

Table 7, for example, shows minimum pullup resistor values. but in 7.4 "How to size pullup..." exlicits that it is for OD outputs.

However, somewhere in the datasheet says that for PP outputs pull up resistors mey be required.

With which criteria?

thanks in advance.

Re: NVT2008 with pushpull outputs in both sides.

AldoG — Thu, 13 Sep 2018 15:38:29 GMT

Hello, Franco,

The need for pull-ups resistor depends on the application,

e.g.

For Down translation (from Bn to An uni-direction)

Pull-ups resistors may be needed only if the translation VCC(B) - VCC(A) < 1V, on your lower voltage side, be it OD or PP, just to make sure that the voltage high on the low side it is as high as needed, as for your high side no PU are needed.

As for Up translation (from An to Bn uni-direction)

Resistors in both sides may be needed.

Please see AN11127 [https://www.nxp.com/docs/en/application-note/AN11127.pdf] for references, page 9, section 5.3.

Thank you!

Regards,

Aldo.