SYSBOOT PU/PD without resistors

Lars Thomsen

Prodigy 70 points

HI,

Will it be OK to tie SYSBOOT configuration pins directly to GND or VDDSHV6?

I'm designing a system with AM335x without LCD, so the pins are not used for anything else.

Thanks

/Lars

over 12 years ago

0 Biser Gatchev-XID over 12 years ago

TI__Guru**** 393215 points

Hi Lars,

Not a good idea I think. The pins may not be used in your application, but they will switch to their default mode after reset, which is GPIO, and then an inadvertent change of mode/state by software can permanently damage them.

0 Lars Thomsen over 12 years ago in reply to Biser Gatchev-XID

Prodigy 70 points

Hi Biser

Thanks for the fast reply.

I think you are right, if the voltage is 3.3V and the drive strength is 6mA, then the power consumption in each GPIO could be 0.5W and damage the GPIO.

0 Lars Thomsen over 12 years ago in reply to Lars Thomsen

Prodigy 70 points

Sorry wrong calculation it will be 19.8 mW.

Will it still damage the GPIO?

0 peaves over 12 years ago in reply to Lars Thomsen

TI__Guru 63615 points

The 6mA output current is a minimum output current based on specific Vol and Voh voltages and slew rates required to meet AC timing parameters. However, this current could be much higher. If you short an output operating powered by 3.3 volts supply, the current could exceed 150mA per pin.

Regards,
Paul

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SYSBOOT PU/PD without resistors