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DAC7551: How to use VREF

cafain
Mastermind 6365 points
Part Number: DAC7551

Hi,

Please tell me how to use VREF of DAC7551.

Method of generating VREF voltage by voltage drop of external resistor

Square blocks are DAC7551
The resistor is connected to the outside of the device.
External resistor RVREFH is connected to VREFH of DAC7551 with 3.3 V power supply,
External resistor RVREFL is connected to the VREFL terminal of the DAC7551 and GND.
Even if a VREFH and VREFL voltage is created by such a connection circuit,
　is there a problem as a DAC operation?

Specifications are VREFH = 3.017 V, VREFL = 0.197 V

best regards

  • 0
    TI__Genius 14220 points

    Hi Cafain-san,

    The reference input impedance would vary by +/-20% causing a variation in the reference voltage due to the voltage divider network. This will result into gain error. Another point is that the power supply ripple and noise will directly reflect on the reference voltage and will appear at the output through the unity-gain output amplifier.

    Regards,

    Uttam

  • 0 in reply to Uttam Sahu
    Mastermind 6365 points

    Please continue to ask me a question

    Connect a resistor to the power supply and the VREFH terminal, and similarly connect a resistor to the GND and VREFL terminals,
    Is there a possibility of damage to the device?

    Even if both resistors are removed and VCC and VREFH terminals are connected directly,
    　and also the VREFL terminal is connected directly to GND,
    　code "0" will not output a voltage near GND,
    　Code "4095" will also output a voltage near VCC Will not be output.

    Does it cause damage to the device or performance deterioration?
    I think that it is not related to the absolute maximum rating in particular.

    best regards

  • 0 in reply to cafain
    TI__Genius 14220 points
    Hi,

    I don't think the device will get damaged if VDD-GND is connected across VREFH-VREFL. However, there will always be some non-linearity near the rails. Hence, it is advised to keep some headroom near the rails.

    However, we would recommend not to use the REF input impedance as a voltage divider.

    Regards,
    Uttam