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TLV5632: TLV5632 Vout calculation

Moshe Levy
Prodigy 30 points
Part Number: TLV5632
Other Parts Discussed in Thread: TLV5630, TLV5631

Tool/software:

Hi,

I am trying to figure out how the output voltage is calculated. 

- The  TLV5632 is a 8 bit DAC

- from the datasheet page 10 it is stated that "The output voltage (full scale determined by reference) for each channel is given by:  2*REF * { (CODE/0x1000)}   [V]

where:

   - REF is the reference voltage (2.048V from datasheet)

   - CODE is 0x000 to 0xFF0 for the TLV5632.

In page 12 it is stated that: "The TLV5630 decodes all 12 data bits. The TLV5631 decodes D11 to D2 (D1 and D0 are ignored). The TLV5632 decodes D11 to D4 (D3 to D0 are ignored).
               

I tried to calculate the range but can't figure out how the CODE is considered:

- If I reference to the fact that it is 8 bit DAC then the CODE should be 000 to 0x0FF...but then I get output voltage of 0V to 0.255V

- assuming 12bit register  (DATA format page 11) I get potential numbers from 0 to 4096....and taking the range of 0x00 to 0xFF0 (as written above) I get 0 to 4080? so....voltages of 0V to 4.08V?

so where does the (D3 to D0 are ignored) takes action? 

what is the correct output range? 0V to ...?

  • 0
    TI__Mastermind 42273 points

    Hi Moshe, 

    This is correct.

    Moshe Levy said:
    assuming 12bit register  (DATA format page 11) I get potential numbers from 0 to 4096....and taking the range of 0x00 to 0xFF0 (as written above) I get 0 to 4080? so....voltages of 0V to 4.08V?

    In this datasheet, CODE in the equation is referring to DB11 to DB0 for all devices. DB3:0 are ignored in TLV5632 like you said, meaning that only 8-bits are captured (because this is an 8-bit device).

    You could use the equation, VOUT = (CODE/0x100) * VREF, and in this case shift the data left by 4 before writing the data to the DAC. Many DACs use this format so the user does not have to realign the data if they are moving from the 12-bit to 8-bit device. Code 0xFFF will be full-scale on both devices. 

    Best,

    Katlynne Jones

  • 0 in reply to Katlynne Jones
    Prodigy 30 points

    Thank you Katlynne,

    so reading from your answer i see that in the equation you use 0x100 in the divider for the 8-bit DAC and not 0x1000 like the datasheet state for all devices. 

    now it makes sense.