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Original question:

DRV2700: Questions of DRV2700

DRV2700: DRV2700EVM-HV500 - High current draw at certain output voltage

Toby Lane
Prodigy 60 points

Part Number: DRV2700

Tool/software:

Hi there,

I have been playing around with DRV2700EVM-HV500 before committing to using it in a design. I notice a behaviour where the device current consumption is quite variable across the operating range. Here is a table of output setpoint (when in DC mode - driven through the GUI):

Voltage (DC) Ripple (Vpp) Supply Current (mA) @ 5 V
0 1 0
50 30 72
100 60 140
200 12 308
300 60 110
400 35 32
500 15 55

Is it expected that the design draws significantly more current with the output setpoint at around 200 V? The only load on the EVM was an isolated oscilloscope probe. I also captured an image of the board, and you can see that the flyback transformer and output discharge network get very hot at this setpoint.

Thanks in advance for your help.

All the best,

Toby

  • 0
    TI__Genius 11152 points

    Hi Toby,

    What method are you using to adjust the output voltage here? 

    There are many circuits connected to VDRV power rail. At specific output voltages, you may want to optimize the external circuitry around the OpAmp and resistive feedback ladder. I do not have any data on the output current across output voltage range. I suspect what you are seeing could be normal operation. Optimizing the things mentioned may reduce current consumption at specific output voltage levels. 

  • 0 in reply to Kelly Griffin
    Prodigy 60 points

    Hi Kelly,

    Thank you for your reply.

    The output voltage was adjusted using the GUI (Piezo Control Console), which as far as I am aware just drives the MSP430 PWM to the right duty to generate the requested output voltage.

    Another question, it is suggested in a few places in the documentation for DRV2700 and DRV2700EVM-HV500 that the output could go up to 1000 V. Assuming I have suitable feedback network, transformer, output discharge network, etc, is there any reason why I can't reach more than that? 2, 3, or 4 kV?

    Thanks,

    Toby

  • +1 in reply to Toby Lane
    TI__Genius 11152 points

    Hi Toby,

    Got it - I think you may want to switch the SW3 and SW4 switches and look at the power consumption at different output voltage levels. It may be lower.

    For your second question, you can achieve higher and higher output voltages. You just have to redesign the surrounding components. Here is a post with someone asking about 1kV operation: DRV2700EVM-HV500: How to output 1000V using two EVMs - Amplifiers forum - Amplifiers - TI E2E support forums.