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Maximum voltage level for NRF51-dk

Hi, What is the maximum voltage a level than can be given as an input on a pin on nrf51-dk? I've measured VDD at 2.91V. Is it from VDD-0.3 to VDD? If yes, is there a way to give 5v as input to a pin? Thanks in advance for the answer :)

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  • Hi

    Have a look at the Hardware reference files for the nRF51 DK. This is the power supply layout:

    image description

    As you can see, the 5 volts at the USB port is actually the only input voltage with a 3.3V voltage regulator (U3). The battery connector and header P21 is not regulated at all. All three voltage inputs are protected by a Low Forward Voltage Drop diode SD103ATW. The voltage drops across these diodes are ~0.3V. This is why you only see ~3.0V on VDD_nRF when you apply 3.3V on one of the inputs.

    So to answer your question; you can only supply 5 volts to the USB port. The maximum supply voltage of the nRF51 is 3.6V (read the Product Specification). Hence, you can not attach a power supply with voltages greater than 3.9V on the unregulated input ports. This assumes that you have not bypassed the protection diodes so your VDD_nRF voltage will be 3.9V-0.3V = 3.6V.

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  • Hi

    Have a look at the Hardware reference files for the nRF51 DK. This is the power supply layout:

    image description

    As you can see, the 5 volts at the USB port is actually the only input voltage with a 3.3V voltage regulator (U3). The battery connector and header P21 is not regulated at all. All three voltage inputs are protected by a Low Forward Voltage Drop diode SD103ATW. The voltage drops across these diodes are ~0.3V. This is why you only see ~3.0V on VDD_nRF when you apply 3.3V on one of the inputs.

    So to answer your question; you can only supply 5 volts to the USB port. The maximum supply voltage of the nRF51 is 3.6V (read the Product Specification). Hence, you can not attach a power supply with voltages greater than 3.9V on the unregulated input ports. This assumes that you have not bypassed the protection diodes so your VDD_nRF voltage will be 3.9V-0.3V = 3.6V.

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