nRF91 series reset pin pull-up voltage

RE: nRF91 series reset pin pull-up voltage

mathiaso — Mon, 08 Apr 2024 14:01:35 GMT

Hi, Jayant.

Sorry for the delayed response but I've now received an answer regarding the voltage levels of nRESET. The values are found from threshold measurements.

nRESET active when V_nRESET < 0.8V - 0.9V (normal mode to reset state).
nRESET release when V_nRESET > 0.7V - 0.8V (reset state to normal mode).

RE: nRF91 series reset pin pull-up voltage

mathiaso — Thu, 21 Mar 2024 12:45:59 GMT

I have btw created an internal ticket regarding the nRESET pin LOW level voltage not being included in the PS. So hopefully it will be included there in the future.

RE: nRF91 series reset pin pull-up voltage

mathiaso — Mon, 18 Mar 2024 16:43:20 GMT

Hi, Jayant.

Sorry for the late reply.

I have neither been able to get a conclusive answer about this from anywhere, nor have I been able to test it, but your reasoning sounds like it makes sense.

I'm happy to hear the issue has been fixed.

Best regards,
Mathias

RE: nRF91 series reset pin pull-up voltage

Jayant Tang — Fri, 15 Mar 2024 02:58:18 GMT

Hello Mathias,

The customer cares about what is the real low level of the nRESET. Is it 2.2x0.3 = 0.66V? We have tested it that the 9161 will reset at about 1.0V.
By the way, the reset issue has been fixed after adding a capacitor.

Best regards,

Jayant.

RE: nRF91 series reset pin pull-up voltage

mathiaso — Tue, 12 Mar 2024 14:41:54 GMT

Hi, Jayant.

[quote user=""]1. The spec says there is a pull-up resistor inside the SiP. Why the voltage is 2.2V? The high level of a GPIO is 0.7 x GPIO_VDD = 0.7 x 3.3 = 2.31V. The 2.2V should be an undefined level.[/quote]

The reason is that nRESET and the GPIOs are connected to different voltage domains.

[quote user=""]2. If add an external pull-up resistor to 3.3V, will it bring more power consumption?[/quote]

Adding an external pull-up resistor to 3.3 V will feed the internal 2.2 V voltage with a voltage that then is higher. This is not recommended. As can be seen in the picture you included above, "driving nRESET high with a voltage lower than 2.2 V will result in additional leakage".

[quote user=""]3. Is external pull-up resistor necessary? [/quote]

No, there should not be used an external pull-up resistor. See the note in the pin assignments as well.

Best regards,
Mathias