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TM4C1290NCPDT: If not all VDD pin connect to power source, what's the risk thing?

erik lee2
Genius 3060 points
Part Number: TM4C1290NCPDT
Other Parts Discussed in Thread: TM4C1294NCPDT,

hi,

i made a TM4C1294NCPDT PCBA, but now i want to replace it by TM4C1290NCPDT,

both of these 2 chips almost pin-pin compatible but PIN63, what risky thing will happen if TM4C1290NCPDT's pin63 doesn't supply with power source?

  • 0
    Guru 117855 points

    Good that you asked - do note that the MCU manual lists "limitations" upon current draw from (each) of the 4 sides of these MCUs.    (true beyond this vendor, alone)

    Having past worked @ a similar, "Semi-Giant" it is usual that multiple such VDD routings connect to the "power bus" - on a "Per MCU Side" basis.     

    While I've no access to this MCU's "internals" - it is likely that the ability to "source GPIO Output current" and certain (other) performance aspects - from that side of the MCU - will be compromised.   (should you leave pin 63 unconnected to VDD.)      Such is true especially under full speed System Clock, multiple GPIOs set to Output, and elevated temperatures.

    Pin 69 (right side of the MCU) appears the nearest "source of VDD" to your pin 63 - you should be able to engineer (some) interconnect...

  • 0 in reply to cb1_mobile
    TI__Guru*** 135355 points
    Hello erik,

    VDD on Pin 63 needs to be connected. Possible effects of not connecting could include the device going into BOR because of lack of power being supplied. You probably can understand we don't run tests with single VDD rails disconnected to characterize failures, so just please ensure the customer connects VDD as it is supposed to be for their design.