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DAC53204: No voltage output

kurt labes
Prodigy 30 points

Part Number: DAC53204

set all 4 output as voltage output

i2C command sequence:

DAC_1,2,3,4_VOUT_CMP_CONFIG_REG = 0x1000
DAC_1,2,3,4_FUNC_CONFIG_REG = 0x0700
COMMON_CONFIG_REG = 0x0249
DAC_1_DATA = 0x3000
DAC_1_DATA = 0x1C00
DAC_1_DATA = 0xC000
DAC_1_DATA = 0x3C00

vref is connected to vdd
registers are read back -> as set per list above

voltage outputs are 0!

thanks for your help
best regards
kurt

 

 

  • 0
    TI__Mastermind 23425 points

    Hi Kurt,

    Can you share your schematic?

    Also, can you share some scope captures of the I2C commands? When you read the registers are you saying that all your data writes are sticking and coming back as the expected values?

    What value is read back from the GENERAL-STATUS and CMP-STATUS registers after you attempt this power up?

    Regards,

    James

  • 0 in reply to James Steenbock
    Prodigy 30 points

    Hi James,

    sorry for the delay.

    checking the sent data to register is the same as coming back. I changed the clock speed, no difference.

    only thing I think is a problem? pin 5 GPIO/SDO is not connected to anything, could that be a problem? 

    Datasheet:
    "If unused, connect the GPIO pin to VDD or AGND using an external resistor"

    the gap between wr/rd cycles ~13us (clock high -> clock low)

    best regards

    Kurt

  • 0 in reply to kurt labes
    Prodigy 30 points

    sorry forgot

    GENERAL-STATUS = 0x2008

    CMP-STATUS = 0x000F

  • 0 in reply to kurt labes
    Prodigy 30 points

    Vref connected to vdd connected to 5V

  • 0 in reply to kurt labes
    TI__Mastermind 23425 points

    Hi Kurt,

    I'm thinking the problem might be your first command DAC_1,2,3,4_VOUT_CMP_CONFIG_REG = 0x1000

    According to the data sheet, this is setting the VOUT-GAIN-X bit field to 100'b which causes your gain to be x3 and uses the internal reference voltage rather than your external 5V.

    This requires the internal reference voltage to be enabled and if we look at your later command COMMON_CONFIG_REG = 0x0249, we can see that the bit field for EN-INT-REF is being set to 0'b

    So a couple things you can try:

    • Change the first command to something like DAC_1,2,3,4_VOUT_CMP_CONFIG_REG = 0x0400 to see if that allows you to use VDD 5V for the reference with a Gain setting of x1

    • Keep DAC_1,2,3,4_VOUT_CMP_CONFIG_REG at the same value you originally shared but try using COMMON_CONFIG_REG = 0x1249 to see if enabling the internal reference allows for the outputs to engage (the internal reference generates a fixed 1.21-V voltage typically).

    If you haven't been using the GPIO or writing to the GPIO-CONFIG register, it shouldn't be affecting the outputs (default state is "unused"). The pin should be tied high or low according to the datasheet so I would implement that to be safe, but I'm not certain that's your issue since the pin shouldn't be affecting anything by default. Read back the GPIO-CONFIG register just to verify it's set to 0x0000.

    Regards,

    James