Does System Voltage Effects nrf51822 BLE Range

[Lucas]

Hello,

My team and I are trying to decide how to power the nrf51822. We will be using a 3.7V lithium ion battery as our power source.

I saw in another post that it is not advised to use the internal DC/DC switch mode converter when softdevice S110 is being used. Is this only referring to the internal DC/DC converter? Or does this also apply to an external DC/DC converter.

Additionally we are trying to decide what Vdd should be set at. As you know, lithium ion batteries can range from 4.2V-2.7V. Therefore, we were planning to use a 2.5V LDO or DC/DC converter. One of the members of my team is curious weather the eternal Vdd voltage effects the range of RF communication. If it does we may consider using a 3V LDO or DC/DC converter for extra power.

In any case, we plan to protect the lithium ion battery from depletion beyond 90% depleted using the ADC to measure battery voltage, system off to put the battery to sleep, and the LPCOMP to wake the device back up after charging.

Any information you may have is helpful

Thanks, Lucas

[Håkon Alseth]

1. The restriction is towards our internal DCDC regulator, as it has such a long stabilization time. You are free to use an external DC/DC regulator for your application.

2. The VDD voltage will not have any effect on the range. If you are running the nRF51x22 in a normal LDO mode (using nRF51x22's LDO, not external) and using an external DCDC regulator, it will be most efficient power-wise to use a lower nRF-voltage (~2 V) due to the internal nRF-LDO burning off inputvoltage - outputvoltage. Ie: the nRF51x22 will use the same current for the accepted VDD area (1.8V to 3.6V)

[Håkon Alseth]

Yes, that is correct. So, if the VDD set to 3.4V, you will use more power (mW) than if you lower VDD to 2.0V. We are not using many regulators in general (some LDOs, from 5V to 3.3V), as most of our reference designs are powered with coin cell batteries.