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pringle1991
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Registered: ‎04-01-2016

Zynq with different bank voltage and IIC pullups voltage

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Hi,

 

 

     I am having a doubt with IIC design on zynq on hardware level. I have connected BANK 501 MIO VCC to 1.8V and connected IIC SDA SCL (MIO 51 and 50 respectively)pins  to 2.5V VCC or 3.3V VCC via pull-up resistors. Will it be Okay if I am working in this setup or should I connect my SCL SDA pins to 1.8V itself? I have attached image (top level block diagram of implementation) of same. Please note that in vivado design suite , we are configuring IOTYPE as 1.8V for corresponding pin.

 

Expert opinion needed.

Block diagram.jpg
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u4223374
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1,169 Views
Registered: ‎04-26-2015

From DS187, Table 1: Absolute Maximum Ratings - the maximum allowed PS MIO voltage is VCCO_MIO + 0.55V. If you feed the pin 2.5V or 3.3V, you are likely to do permanent damage to the chip. Either that or the clamp diodes will pull the I2C line down to about 2.3V anyway, which will just waste power and may result in the 3.3V I2C slave not working correctly (Xilinx provides virtually no information about 7-series clamp diodes, so it's hard to be sure).

 

It would be much better to do this "properly" - either run the I/O at 3.3V, or run it at 1.8V and fit an I2C level shifter.

 

 

 

 

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u4223374
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Advisor
1,170 Views
Registered: ‎04-26-2015

From DS187, Table 1: Absolute Maximum Ratings - the maximum allowed PS MIO voltage is VCCO_MIO + 0.55V. If you feed the pin 2.5V or 3.3V, you are likely to do permanent damage to the chip. Either that or the clamp diodes will pull the I2C line down to about 2.3V anyway, which will just waste power and may result in the 3.3V I2C slave not working correctly (Xilinx provides virtually no information about 7-series clamp diodes, so it's hard to be sure).

 

It would be much better to do this "properly" - either run the I/O at 3.3V, or run it at 1.8V and fit an I2C level shifter.

 

 

 

 

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necare81
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Registered: ‎03-31-2016
No, that is not safe for the Zynq device.

Vin max is VCC_MIO + 0.3V. So no more than 2.1V should be used on the pullups.