Power up sequence of VC5509A

Peng Liu50174

Other Parts Discussed in Thread: TMS320VC5509A

Hi,

I have two questions about the power up sequence related to TMS320VC5509A on the board.

1) Is there a power-up sequence requirment about the I/O voltage DVDD and Core voltage CVDD?

2), On our board there is one 1.8V voltage source which is connected to 5509A's ADC input port for monitoring. This 1.8V is powered up earlier or at the same time of DVDD and CVDD. Is this a risk to C5509A as ADC input is driven before its DVDD and CVDD are well powered up?

BTW: I haven't found any description about these two situations in the datasheet and application notes.

Thanks,

over 14 years ago

0 Steve Tsang over 14 years ago

TI__Mastermind 23785 points

1) There is no specific power up sequence requirements.

2) Caution here not to cause I/O contentions or floating inputs at the ADC pins when powering up and down.

Regards.

0 Peng Liu50174 over 14 years ago in reply to Steve Tsang

Expert 1510 points

Hi, Steve,

Thanks for your reply.

There should be no I/O contentions on our board during the Power up/down.

Our team just think, that when DSP's ADC port input pins are driven by external source before the DSP chip powers up may cause potential damage to the DSP chip.

BTW: I have a look at http://focus.ti.com/lit/an/sprab14/sprab14.pdf. In the table 1 in page 11, it says the ADC port AIN0~3 can be left unconnected if not used. But on our boards, these ports are all used, none is floated.

Best Regards,

Peng

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Power up sequence of VC5509A