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Original question:

DRV2700: Reference Design of 1000V output

DRV2700: How to Design of 1000V output by Flyback mode?

user4384760
Prodigy 20 points
Part Number: DRV2700


Dear Specialists,

  we would be grateful if you could advise。 How to use  DRV2700 for piezo driver with High voltage（1000V ac@flyback mode） and we have some questions and want some design information（For example： calculation of parameter design，but the user guide is not given ）.

 According to the datasheet P.12 8.4.2 Flyback Mode, DRV2700 can drive 1000V output by using Flyback mode,but  "slou407a" user guide is not given  about transformer design information,only feedback network parameter modification is given.then we use the TINA-TI Reference Design "slom404.tsc",we aslo couldn't find 1000V output(about 600V) by  feedback network parameter modification(R5 is changed from 5.11k to2.56k, C5 is changed from 8.2nF to 16.2nF,the other parameters remain the same). 

we questions as foollow :

1.  I'd like to know about transformer, because I couldn't find 1000V output by Flyback mode.

2. how to choose  transformer  saturation current ,turns ratio  and inductance value , etc  ?   Reference Design "slom404.tsc" is simple inductance and mutual inductance,we want to know transformer parameter for   1000V output by Flyback mode.

3. Is also  there a detailed user's manual for the design of 1000v output by Flyback mode, which contains the calculation of the whole Flyback mode circuit parameter design, we want do WCA (Worst case analysis) .

I appreciate your great help in advance.

Best regards,

yunbai qin

  • 0
    TI__Guru* 84915 points

    Hi, Yunbai,

    Welcome to E2E and thank for your interest in our products!

    The DRV2700EVM-HV500 would be a good start if you are looking to configure your own flyback circuit:

    http://www.ti.com/lit/ug/slou407a/slou407a.pdf

    The aspects to consider when choosing a transformer are the ration (basically, 1:10 is enough tor reach an output of 1000V). But the saturation current of the primary is also important. Please notice that the Rext resistor will limit the current on the primary. If the saturation current is below this limit current, there could be issues with your design. So, please select a transformer with a higher saturation current value.

    You may even use the EVM and select different gain resistors in order to reach the maximum output voltage.

    I hope this helps you. Please let us know if you have additional questions or comments.

    Best regards,
    Luis Fernando Rodríguez S.

  • 0 in reply to Luis Fernando Rodriguez S.
    Prodigy 20 points

    Hi,Luis,

    Thanks for your quick answer,We still have some questions to ask you with 1000HV drive@flyback mode.

    1. Now we can't find a suitable saturation current of the transformer ,Please recommend some new transformers.

    2.TI Provides parameter selection calculations is simple in slou407a.pdf file,  Can give a detailed design 1000V HV@ flyback mode?

    Best regards,
    yunbai qin.

  • 0 in reply to user4384760
    TI__Guru* 84915 points

    Hi, Yunbai,

    Unfortunately, we cannot recommend transformers in this case.

    However, I would suggest to use the same transformer or similar than the one used on our EVM ( http://www.ti.com.cn/cn/lit/ug/slou407a/slou407a.pdf ). You may even order this EVM and experiment with the resistors to modify the output gain in case you are interested.

    Best regards,
    Luis Fernando Rodríguez S.