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SN6501: Can I use SN6501+Transformer for analog value isolation?

Part Number: SN6501

I'm looking for a concept for analog value isolation.

I have an idea which is to use SN6501+Transformer.

The transformer could be 760390012 (1:1.1). The VCC of SN6501 is the analog voltage to be sampled, the VCC voltage range could be 4...5V (Maybe I can change to 4.5...4.9V). (Circuit pls see below)

My question is:


What will be some affection to the chip when VCC=4...4.5V of SN6501 (When it's out of VCC required range)?


Is the output voltage (V_ADC) 1.1*VCC all the time? (Linear from Input to Output)

Thanks a lot in advance!

  • Hi Jian Jin,

    Thank you for posting, and welcome to E2E!

    It appears the image of your circuit did not upload, please attempt to share it again if necessary.

    As Vcc increases, the SN6501 switching frequency increases and internal FET resistance decreases. This device supports operation of Vcc from 3V to 5.5V, so there no issues are expected if Vcc ranges from 4V - 4.5V. If the 5.5V specification is exceeded, the device will likely be damaged.

    With some minor tolerance for parasitics, the power supply output voltage will display a linear relationship to the input voltage, multiplied by the transformer turns ratio as you mentioned: Vout ~= N * Vin


    Let us know if you have additional  questions.


    Respectfully,
    Manuel Chavez

  • Hello Manuel,

    Thank you very much for your reply. And I attached my concept in below.

    I found VIN of WE 760390015 is required as 3.3V in datasheet. And frequency is 250...550kHz for WE 760390015.

    But My application is: VCC2 (VCC input of SN6501) is 4...5V.

    So I'm worried about the application. You mentioned that the frequency is increased when VCC is increased. from the datasheet of SN6501, I guess that the frequency might be 270...620kHz in SN6501 when VCC is 4..5V, it's not suitable for WE 760390015, right? But what's the problem if the frequency is out of the requirement of WE 760390015?

    Thanks a lot in advance!

  • Hi Jian Jin,

    You're welcome, and thank you as well for uploading your concept.

    Although the recommended voltage input for transformer 760390015 is 3.3V, its Voltage-time product is compatible with 3.3V - 5V operation of SN6501. There is not necessarily a problem to expect from a faster switching frequency except slightly lower output efficiency due to switching losses.

    Is this system expected to operate in temperatures >85dC? The NSR0520V2T1G Schottky diodes should be replaced with diodes of that have >20V reverse voltage specs, and if expected to operate in high temperatures, with low reverse-leakage current as well like RB168MM-40.



    Thank you, and have a great weekend!
    Manuel Chavez