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CC2540 Chip get into high current mode

nelson chong1
Prodigy 105 points
Other Parts Discussed in Thread: CC2540

Hi All, 

Question: Is there any condition that would cause the CC2540 to latch up or draw high current?

Background: My colleague and I have seen a few of the prototype boards that got into high current mode.  These prototype devices, were designed by the third party, and only for detecting some button presses and drive couple LEDs. These devices were originally functional, until we powered up the device at lower voltage around 2.1 - 2.3 V and vary the supply voltage between 2V to 3V, at one point these devices got into high current mode and drawing 400ish mA, and HW POR didn't help. I am assuming something probably got latched up and drawing high current and causing the chip to heat up. Unfortunately, these prototype boards we got from third party didn't have voltage regulator at the front end of the CC2540. So, I am curious if anyone know if there is a condition when varying voltage could cause the CC2540 to get into high current mode? We never lower the supply voltage to below 2 V or over 3 V. 

Thanks,

Nelson

  • 0
    Guru 735685 points

    Would you specify which FW you run on your CC2540?

  • 0
    Guru 31280 points

    Hi,

    I highly doubt that CC254x itself draws so much current.

    Look for troublemakers in:

    • Peripheral electronic parts (LEDs)
    • short circuited GPIOs
  • 0 in reply to Igor Sherer
    Prodigy 105 points

    Hi Igor,

    Thanks for your feedback.

    The other possible causes I am suspecting is the inverter(SN74AHCT14PWR), since this prototype, designed by the external design house, uses the GPIO pins from CC2540 to drive an inverter. The only problem is that the inverter was powered by 5 V through a regulator, but the CC2540 is powered directly from battery. So I am suspecting that when we test the device at lower voltage like 2 V - ish using power supply, it could get to an intermediate state where the both PMOS and NMOS turned on at the same time and resulted in high current since the inverter is still at 5 V from the regulator. Or it could be due to the fact that the slow varying voltage causes the inverter to oscillate. But it is oscillation or if it is inverter latch up, when we reset the voltage to 3V and power the device back up, hw POR. The problem should go away. Besides, when we pull reset line low at the CC2540 (pin 20), the chip doesn't response to the reset. HW POR does nothing either. Any thought?

    Thanks,

    Nelson 

  • 0 in reply to nelson chong1
    Guru 31280 points

    Nothing...

    If you could share with us the schematic of your circuit, we may try to help you out.