RE: Can the nrf9160 sim card be powered by an external hardware circuit?

Didrik Rokhaug — Tue, 12 Jan 2021 09:59:13 GMT

Hi,

That doesn't sound like a good idea to me. There are at least four problems you can or will run into:

1. The LTE specification sets some limits for when the SIM card can be turned off. If you were to turn off the SIM card yourself, you would have to make sure you are compliant with the specification.

2. Many SIM cards does not let you turn them off because that would wear out the flash in the SIM card very fast. This could reduce the lifetime of your project significantly.

3. When booting up, the SIM card will draw a significant amount of power. You might end up using more power by turning the SIM card off often, for short periods.

4. The application does not have enough information about the timing of what happens on the network side, so it will be hard for the application to power on the SIM card at the right moment.

You can use the %XDATAPRFL AT command to shorten the time before the modem turns off the SIM card. But, as explained in point 2, the effect this has on the power consumption might be limited.

Best regards,

Didrik