TUSB522P: The voltage of EQ2 when floating

Jim CHEN

Part Number: TUSB522P

Dear Team,

My customer used three TUSB522p on their board. We made EQ2 floating and measure the voltage, we found that the value of voltage is 0.56V only.

But the spec said that the floating voltage should be Vcc * 0.36 (typ). Vin=3.3V. Vf should be 1.188V.

And then we measured another port and get 0.54V also.

0.54V and 0.56V are lower than VIL=0.66. So our EQ2 only get 3dB, am I correct?

Thank you.

Jim

over 7 years ago

0 Brian Zhou over 7 years ago

TI__Guru**** 162861 points

when EQ pin floating, it should be 6db

0 Jim CHEN over 7 years ago in reply to Brian Zhou

TI__Expert 4795 points

Hi Brian,

It should be 6dB. But what is the expected voltage of EQ pin when floating?
Is 0.54V a normal floating voltage?

Please help to clarify.
Thank you.
Jim

0 Brian Zhou over 7 years ago in reply to Jim CHEN

TI__Guru**** 162861 points

how you measure it? scope or multimeter? did you turn off pullup/pulldown?

0 Jim CHEN over 7 years ago in reply to Brian Zhou

TI__Expert 4795 points

Hi Brian,

We used multimeter to measure it. We didn't mount the pullup or pull-down resistor. So it should be floating.
Is there any concern?

0 Jim CHEN over 7 years ago in reply to Jim CHEN

TI__Expert 4795 points

Hi Brian,

Today I measure the voltage of EQ pin on TUSB522p EVM. The voltage is about 1.17V. This should be the correct floating voltage.
So I think it seems like the customer's board has some issue we need to debug further.

Jim

0 Brian Zhou over 7 years ago in reply to Jim CHEN

TI__Guru**** 162861 points

when floating, there is internal pullup/pulldown resistor during reset. after reset, internal resistor may disabled.

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TUSB522P: The voltage of EQ2 when floating