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Original question:

MSP430FR2433: MSP430FR2433

MSP430FR2433: MSP430FR2433

Liang Zhou
Prodigy 40 points
Part Number: MSP430FR2433

Hi, 

I have a GPIO pin which is configured input with a programed pull down.  

I'd like to ask what will happend if i give an input voltage more than Vcc+0.3 with Vccmax=3.2V.

There are internal protection in the GPIO? Because i feel that whatever the input voltage, i get only 4V at the GPIO pin.

Thank you

Best regards.

Liang  

  • 0
    Expert 1780 points

    Yes, there are internal ESD structures (diodes) on the pins to both VCC and GND. You are forward biasing a low power diode and will damage the device if you put a higher voltage than the Absolute Maximum stated in the datasheet.

  • 0 in reply to Seth Jackson
    Prodigy 40 points

    Thank you for your relay. The absolute maximum value is a peak vleur of an anverage value? 

  • 0 in reply to Liang Zhou
    Expert 1780 points

    Any voltage above VCC+0.3 will start conduction on the diodes. You SHOULD NOT be applying ANY signals, peak or average, higher than VCC+0.3 if you want your MCU to have any kind of life span.

  • 0 in reply to Liang Zhou
    TI__Genius 17490 points

    Hi Liang,

    Can I ask what your inputs are that you need to go over the recommended operating conditions? As Seth mentioned, any value crossing the absolute maximum ratings will damage your device.

    The recommended operating condition for VCC is maxed at 3.6 V and going above this can still cause damage. So if you have the absolute max input at the maximum recommended VCC you will still be under the 4V. 

    Would using a voltage divider to tune down your input signal be applicable in your application?

    Regards,

    Luke

  • 0 in reply to Luke Ledbetter
    Prodigy 40 points

    Hi Luke, 

    The VCC is about 3.2V for our application. 

    My question concerne about the Voltage applied to GPIO. 

    The architecture aims to activate µC by set input high to a GPIO. 

    My input is an electromagnetic pulse, generated by the device's near-field antenna from an external signal generator. The stength of the input voltage depends on antenna's position which is random. 

    As shown in the figure, the R1 is µC internal configurated pull down.  The diode and the following capacitor is a half rectifier to transfert the input sinus signal to a smooth DC voltage. 

    I tried to divided the signal by set R4, but this cause activation no efficency.

    However, my µC doesn't looks like KO after serval activation test by GPIO. 

    What kind of errors can be caused if  Voltage applied to GPIO is higer than recommanded? 

    Thank you in advance 

    Best regards 

    Liang 

  • 0 in reply to Liang Zhou
    Guru 35640 points

    If you violate the absolute maximums, you bought the device.The point is TI can't tell you what might happen, because they don't do any testing there. If you burn out the ESD diode, you leave the chip unprotected.

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