Questions on nRF51822 Hardware

[Vincent]

I would like to ask you some questions on nRF51822 Hardware:

1. From nRF51822 datasheet, a 16M or 32M external clock is needed, now if we have one 26M TCXO is available in system. Can nRF51822 work with external 26MHz clock input (0.9Vpp, +/-2ppm)?

2. In 1.8V power supply mode, if we can provide one 1.8V IO voltage for nRF51822, can you tell me 1.8V requirement (maximum consumption current?, ripple?...)

[Stefan Birnir Sverrisson]

Hi

1. The choices are 16MHz or 32MHz. Nothing in between will do.

2. Currently we recommend to use the LDO supply mode. For the upcoming nRF51 revision 3 chip, DCDC mode will also be usable when the softdevice is enabled, see our recommendation on this thread. For the LDO mode, the spec says that the supply voltage should be 1.8V - 3.6V, so you should keep the supply voltage at 1.8V or above, also when you include the ripple in the supply voltage. We have measured 100mV peak to peak ripple on the supply voltage in LDO mode to be all right, and only have minor effect on radio sensitivity. Degration of radio sensitivity is about 1dBm - 2dBm with 100mV ripple in LDO mode, so if your ripple is smaller than 100mV, that should be safe. Maximum consumption current is around 30mA