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DAC8551EVM: Block Diagram Question

Jim CHEN
Expert 4795 points
Part Number: DAC8551EVM
Other Parts Discussed in Thread: DAC8551

Dear Team,

My customer has one motor driver project that would like to use DAC8551 to generate an adjustable voltage.

There is a PWM signal is sent from the motor driver to MCU, MCU would base on this PWM signal to adjust DAC8551 output voltage.

Now they have some questions about EVM block diagram as below. 

1. For above application scenario, do they need to use output buffer module(U2_OP AMP)? Why? 

2. Could they tie VrefH to external reference module(U3/U8A) directly? 

3. Could they tie Vout(pin4) to the input of other device? 

Thank you.

Regards,

Jim

  • 0
    TI__Mastermind 18976 points

    Hi Jim,

    The EVM has been designed to evaluate different combinations of output (Say gain of 1, 2, etc)

    For your specific questions,

    1. For above application scenario, do they need to use output buffer module(U2_OP AMP)? Why?

    U2_OP_AMP is used as a unity gain buffer or gain of 2 . You can always disconnect this and use DAC8551 output. Whats the current requirements for this drive ( from DAC)?

    2. Could they tie VrefH to external reference module(U3/U8A) directly?

    VrefH is used as DAC reference voltage, since this device has no internal buffer, you need to drive this node with a buffer as shown in the schematics (U8A)

    if customer has buffer, then they can connect VrefH to buffer output.

    3. Could they tie Vout(pin4) to the input of other device?

    Since Vout is DAC output voltage, it really depends on the other circuit's input impedance (should be high) whether you can directly connect this or not.

    I assume DAC output will be connected to some sort of buffer.

    Regards,

    AK