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AMC1306E05: use negative gate supply voltage?

Part Number: AMC1306E05
Other Parts Discussed in Thread: AMC1304M05

Hi,

when I have a 10V/-5V isolated gate drive supply the datasheet would recommend to use a z-diode and resistor from the 10V, but what about the -5V? Is there any problem with having an inverted analog supply compared to the digital 3.3V supply? 

Thanks.

Regards 

Alex

  • Hi Alex,

    I'm not sure that I follow the 'inverted supply' aspect of your query on the AMC1306E05. From the standpoint of the power needs for the AMC1306E05, the AGND and DGND are completely isolated from each other. You could reference AGND (pin 4) to the -5V rail and zener regulate from the +10 V rail, or simply connect your supply 'ground' to AVDD (pin 1). You could also reference AGND to the 'ground' point between your +10/-5 and zener down from the +10V rail. The DGND side of the AMC1306 won't care either way. The main thing you need to be aware of on the input side is the common mode voltage (see Vcm and Vcmov in the table of section 7.9 from the datasheet).
  • Hi Tom,

    AGND should  stay at the phase level as in the datasheet schematic. I wanted to connect AVDD to the floating gate supplys -5V output. So instead of using some kind of LDO from the 10V above the phase (gate turn on supply), I wanted to use the -5V below the phase (gate turn off bias) as AVDD supply. This way i do not need any LDO to change the voltage. 

    Regards

    Alex

  • Hi Alex,

    Thank you for the clarification - the AVDD rail has to be 5V above the AGND pin, so taking the AVDD to your -5V won't work, you'd have to LDO down from the 10V rail.  One potential option for you would be to use the AMC1304M05, which has a built-in LDO that can take up to 18V (your 10V rail would not need a zener or LDO), but it does not have the Manchester coded data option - it's got a CMOS output.

  • Thanks Tom.

    I use AMC1304 already but wanted to use a smaller footprint. So the AMC1306 seemed ideal but if i need to step down the voltage anyway, I am not any smaller than with the existing solution.

    Regards

    Alex