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CCS/TMS320F28377S: GPIO clamp protection

Houjian Xu
Intellectual 280 points
Part Number: TMS320F28377S


Tool/software: Code Composer Studio

 I didn't find the clamp protection in GPIO of F2837x. So I think there is no clamp protection in GPIO. However, the C2000 MCU can work normally with 5V input because of my carelessness. 

So, there is a clamp protection in GPIO but no statement in datasheet, or there is no clamp protection.

  • 0
    TI__Genius 17370 points
    Hello,
    I am writing to let you know that a C2000 team member has been assigned to this post and should be answering shortly.

    Regards
    Baskaran
  • 0
    Intellectual 280 points
    and the value of the GPIO pull-up resistor is 10k? the default pullup set is disable? and the default GPIO output is high ?
  • 0 in reply to Houjian Xu
    TI__Guru 60865 points

    Hi Houjian,

    The GPIOs will indeed begin clamping if an input is applied that is about 0.3V below VSS or about 0.3V above VDDIO.

    In order to avoid damaging the device, this clamping current should be limited to less than 20mA on a given pin and less than 20mA total for all pins at any time.  It is usually also best to avoid a situation where the pin is being continuously clamped (vs. a short transient clamping event).

  • 0 in reply to Devin Cottier
    TI__Guru 60865 points
    We don't directly specify the pull up/down resistance, but you can find the pull currents in the datasheet table "5.6 Electrical Characteristics".

    There are pull-ups on all GPIO pins and they are disabled by default per section 4.2 Signal Descriptions: "All GPIO pins are I/O/Z and have an internal pullup, which can be selectively enabled or disabled on a per-pin basis. This feature only applies to the GPIO pins. The pullups are not enabled at reset." If you look at the TRM you can also see that the pull-up disable registers (e.g. GPAPUD) are disabled by default based on the reset value of the register.