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dracoxue_946
Visitor
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Registered: ‎02-05-2020

Zynq-7000 SRST and POR (PS_SRST_B and PS_POR_B) Signals release Sequencing on power on

Hi, dear Xilinx's experts,

     I have a question about Zynq-7000 SRST and POR Signals release Sequencing on power on when I designning  a project.

     My project use XC7Z045 series chip. When I was reading UG585, I'm a little confused. Accoding to page 164 figure 6-4,

1.JPG

 PS_SRST_B is de-asserted before PS_POR_B being de-asserted(Pulling High).  But according to page 711,Figure 26-3:2.JPG

It is seems like PS_SRST_B is de-asserted after PS_POR_B being de-asserted for a ram memory clear.

So the what is the suggestted sequence  I should follow?

Thank you for your advance!

 

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allanherriman
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Mentor
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Registered: ‎01-08-2012

You can tie PS_SRST_B permanently high and it will work fine.

Typically SRST is just used for debugging.  For example, on my boards I tie it to a pullup resistor and the JTAG header and ESD protection and nothing else.

 

I use PS_POR_B to reset the board.  This is derived from the power supply supervisor(s).  This does not need to connect to SRST.

dracoxue_946
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Registered: ‎02-05-2020

Hi ,thank you so  much for your  answer and detailed explaination!  On my board I also tie SRST to a pullup resistor. I want to ask you more about this question if you don't mind.

On my board, the voltage of bank PS 500 where PS_POR_B  locates in is 3.3V,  the he voltage of bank PS 501 where PS_SRST_B  locates in is 2.5V.  

During different power supply squencing  power on, should 2.5V power on before 3.3V or after or it doesn;t matter?

Thanks for your help

 

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dracoxue_946
Visitor
Visitor
1,279 Views
Registered: ‎02-05-2020

Hi ,thank you so much for your answer and detailed explaination! On my board I also tie SRST to a pullup resistor. I want to ask you more about this question if you don't mind.

On my board, the voltage of bank PS 500 where PS_POR_B locates in is 3.3V, the he voltage of bank PS 501 where PS_SRST_B locates in is 2.5V.

During different power supply squencing power on, should 2.5V power on before 3.3V or after or it doesn;t matter?

Thanks for your help
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jhouee
Observer
Observer
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Registered: ‎11-27-2015

Hello,

Could you tell me why the PS_POR_B asserted doesn't erase the PL bitstream  if I have PS_SRST_B floating or pulled up  ?

In fact only PS_SRST_B asserted reset my bitstream whatever PS_POR_B status.

 

Br

Johann

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