nRF51422 VDD_nRF design

[PonchoM]

I'm designing my own pcb with a IMU and nRF51422 but i confused,

What's the best choice, LDO, DC-DC or external regulator configuration if I'll use a cell coin?

Someone said that use a external regulator is better for save power consumption and in cases that the battery life is factor, but increment the price. --> devzone.nordicsemi.com/.../

Other issue is that the dc-dc have some troubles with softdevices.

Other issue is that the J'LINK need 3.3 Volt for program the target and in other question that I read that the best functionality for nrf51 is at 1.8V, so?

I have a mess, I hope someone can help me

Thanks!

[Asbjørn]

You can use any of the three options, it's up to your application. Using the internal LDO is the simplest and requires the least amount of external components and it works on the entire voltage range.

Internal DCDC need the voltage to be at least 2.1 V or higher. This shouldn't be a problem with the coin cell battery. Using the internal DCDC require three additional discrete components, but it works fine with the latest version of the nRF51822 chip and softdevices. The softdevice issue that has been restricting the DCDC usage has been fixed.

Using an external regulator and supplying the chip with 1.8 V is the most power efficient as the power consumption will be less. But this requires more external components.

The "J-link lite" that is used on the nRF51 kits requires 3.3 V to work, but you can use the J-Link PRO with level shifter to program the board running at 1.8 V (or any other voltage within the nRF51822 spec).