Why MAXII CPLD only output 1.6v when high (3.3V LVTTL)

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VCCIO and VCCINT are both 3.3v, and the pins are set to 3.3v LVTTL in quartusII, but the output is only 1.6v when high after I downloaded my program into the device(epm240t100c5)

Could any body help me?

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Hi,

is only one output affected ?

Kind regards

GPK

All the outputs are effected~!

All that should output as LVTTL outputs only 1.6v.

S.Z

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All the outputs are effected~!

All that should output as LVTTL outputs only 1.6v.

S.Z

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Hi, what is connected to the outputs ?

Kind regards

GPK

Nothing, No load connected.

I use VOM（Volt-Ohm-Milliammeter）to the measue the Voltage. And the output with pulse, I suspect the pulse cause the VOM（Volt-Ohm-Milliammeter）measurement not accurate. How do you think?

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Nothing, No load connected.

I use VOM（Volt-Ohm-Milliammeter）to the measue the Voltage. And the output with pulse, I suspect the pulse cause the VOM（Volt-Ohm-Milliammeter）measurement not accurate. How do you think?

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HI ,

you could not use a VOM for accurate measurements of pulses. You should use a scope for that. Maybe it is easier to check your board with a simple design, which sets all the pins to high. If you still see the 1.6 V check your I/O and core voltage.

Kind regards

GPK

Thank you so much.

I am trying..