nrf9160 disposable battery

[FZe]

I'm facing some problems when trying to run my custom board on standard batteries.

The device boots fine but when the LTE modem connects I get a reset.

The nrf9160 is v2.

I have no regulators. VDD and VDD GPIO powered by the battery.

• VDD1&2: 47uF+100nF+15pF.
• VDD GPIO: 4.7uF +100nF 
• DEC0: 4.7uF

I have tested two AA's in series ~3.3V, Two different CR123A ~3.2V and a CR2025 ~3.25V.

I get the same behaviour in using power profiler, if I set the output supply to < 3V.

In the power profiler I can see spikes at ~500mA when connecting.

I assume this has to do with low capacitance on the VDD pins, what are the recommended values for this type of application?

I'm also curios to know if others are running their devices on alkaline's and not using any converters?

The spec say: VDD 3-5,5V, VDD gpio 1,7-3,6V and 3GPP compliance = 3.3V

So does this mean that there is only a span from 3.3V to 3.6V?

If any one are using any converter how much current does it draw?

[Craig12]

It sounds like your Alkaline batteries have too high internal resistance and the output voltage drops when the radio starts talking. One option would be to add some bulk capacitance, but as you have observed there is a specification indicating to meet 3GPP RF compliance the minimum voltage is 3.3V.

We have been using an ADP2503 600mA, 2.5MHz Buck-Boost DC to DC converter with our nRF9160's. It will accept an input voltage from 2.3 to 5.5V. The only downside we have is it doesn't have a programmable low voltage lockout (i.e 2.5V for Li-Ion), but for disposable primary cells you probably don't care - and want to run them until they are practically dead.

[FZe]

I did measure the batterys using a cheap usb oscilloscope, they drop when loaded but only about 150mV. I will test to increse the bulk caps

The ADP2503 seems nice but still draws to much current for my application ( 38uA from datasheet )

Have you made any real life measurements on ADP2503 current consumtion ?

Regards