nRF51822 internal LDO output pin

RE: nRF51822 internal LDO output pin

MartinBL — Tue, 19 May 2015 11:08:47 GMT

Yes, it is possible to use an internal 1.2V voltage reference. You can do this by configuring the ADC to use the 1.2V VBG internal reference voltage. Read Chapter 31, "Analog to Digital Converter (ADC)" in the Reference Manual to learn how to do this.

RE: nRF51822 internal LDO output pin

MartinBL — Tue, 19 May 2015 11:04:28 GMT

The peripherals, and the rest of the nRF51, can stand 3.6 volts maximum pr Table 20 in Chapter 7 "Operating Conditions" specified in the Product Specification V3.1.

RE: nRF51822 internal LDO output pin

MartinBL — Tue, 19 May 2015 11:01:48 GMT

As you can see in the figures in Chapter 12 "Power management" in the reference manual the DEC1 & 2 pins are connected to two internal voltage regulators, one 1.2V LDO and one 1.7V LDO. Some customers want to use these output pins to supply external components with 1.7 or 1.2 volts. This is not recommended.

RE: nRF51822 internal LDO output pin

Luka — Tue, 19 May 2015 09:56:54 GMT

Martin: is possible to use 1.2 internal LDO as voltage reference for analog comparataor so ~few uA?

RE: nRF51822 internal LDO output pin

Anton — Wed, 13 May 2015 10:47:01 GMT

I didn't know hat LDO providing power to internal circuitry only. I thought that could provide other peripherals. On second thougth, peripherals could stand li-polymer voltage range.

Thanks for your hlep.

RE: nRF51822 internal LDO output pin

Anton — Wed, 13 May 2015 10:42:36 GMT

I'm not clear in your last sentence. "If you are thinking about using the nRF51's LDOs by hooking up to the DEC1 or DEC2 pins this is something we don't recommend. "

RE: nRF51822 internal LDO output pin

MartinBL — Wed, 13 May 2015 10:36:28 GMT

Hi. I'm not sure if I understand you correctly, but the voltage you will get on your GPIO pins is always equal to VDD, independent on what DC/DC or LDO configuration you use. The DC/DC and LDOs is only providing power to internal circuitry like the radio, flash, system, etc. Some of our customers ask if they can provide power to external components by using the DEC1 and DEC2 pins. As you can see in Chapter 12, "Power Management", in the Reference Manual V3.0 these pins are connected to internal LDOs, but they are only intended to be used for decoupling capacitors. We don't recommend using these pins as power supplies for external components and doing so will be at your own risk.

Also, 3.7 volts connected to VDD is beyond maximum specification, as specified in Chapter 7, "Operating conditions", in the Product Specification document V3.1. The maximum supply voltage is 3.6V and higher voltages than this might destroy your chip. If you want to use this kind of battery you will need an external voltage regulator.