Nrf52832 VIH and VIL

[Gueston]

Hi,

I am checking the voltage range on the input pins of the Nrf52832. The specs show VIH is 0,7*VDD and VIL is 0,3*VDD. I'm using the Nrf52DK, which has about 2.8V VDD.

Which means a high input should be triggered from 1.96V and above, low should be 0.84V and below. However, I measure a high from 1.8V and a low from 1.1V, which is not conforming specs.

Am I doing something wrong or is there a software setting for this?

[Håkon Alseth]

Hi,

 

Which means a high input should be triggered from 1.96V and above, low should be 0.84V and below. However, I measure a high from 1.8V and a low from 1.1V, which is not conforming specs.

Below VDD*0.7 and over VDD*0.3 is undefined, meaning that you can read both '0' and '1' in this range. Your measurements is consistent with the specification.

 

Kind regards,

Håkon 

[Gueston]

Yes I know it's the undefinied region, which is good. But 1.8V is 0.64*VDD and 1.1 is 0.39*VDD, which is not consistent with the spec. The specs says VDD*0.7 and ABOVE, but I measure from 0.64 and ABOVE for VIH.

[Håkon Alseth]

It is consistent with the specification.

There's a guarantee that a voltage of VDD*0.7 (or higher) gives a '1' on the pin. Do you measure anything other than '1' on the input when VDD*0.7 or higher is applied?

 

Kind regards,

Håkon

[Gueston]

Ah ok, like that. I understood it wrong, thought it was a schmitt trigger input, which doesn't read anything in the undefined region.

[Gueston]

So, in order to avoid readings in the undefined region, it's better to use the comparator with hystersis I guess?

[Håkon Alseth]

Hi,

 

Gueston said:

So, in order to avoid readings in the undefined region, it's better to use the comparator with hystersis I guess?

Yes, you are right.

 

Kind regards,

Håkon