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Problem with ouput voltage VISO of ADUM6403

Hello,

we are using the ADUM6403 using 3.3V for the primary supply voltage and connect the Vsel pin to GNDiso. In this configuration the output voltage on the VISO pin can up to 5.04V instead of 3.3V.

The power supply voltage is good. We did also the following configuration:

- Vdd1 to 3.3V

- GND1 to GND

- Via, Vib, Vic, Vid are not connected

- Vddl to 3.3V (same used for Vdd1)

- GNDiso to GNDiso

- Vsel to GNDiso

- Vod, Voc, Vob, Voa are not connected

A resistor of 160Ohm is connected between the VISO pin and GNDiso. We have also connected a 0.1uF and a 10uF on the output VISO pin. On the tested device, the output voltage is 3.7V (see the attached file).

Do you have any ideas?

Thank you for your answers.

Sorry for my english

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  • Sebastien:

    I don't think this is normal behavior for the use of the ADuM6403.  I have an idea that you may have a voltage on the inputs VIA, VIB or VIC from your VCO signals that is above the setpoint of VISO = 3.3V and is raising the VISO voltage from the input signal through an internal ESD diode to the VISO pin.  Measure the voltages on the VIA, VIB or VIC with a scope to see if any of these signals raise above the normal 3.3V level.

    Regards, Brian

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  • Sebastien:

    I don't think this is normal behavior for the use of the ADuM6403.  I have an idea that you may have a voltage on the inputs VIA, VIB or VIC from your VCO signals that is above the setpoint of VISO = 3.3V and is raising the VISO voltage from the input signal through an internal ESD diode to the VISO pin.  Measure the voltages on the VIA, VIB or VIC with a scope to see if any of these signals raise above the normal 3.3V level.

    Regards, Brian

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