• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 46 subscribers
  • Views 767 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DAC81416: DAC81416 Maximal current capability

David DA SILVA
Prodigy 40 points
Part Number: DAC81416

Extract of datasheet : dac81416.pdf (SLASEO0A)

 

Dear,

Can you please confirm current capability of DAC81416 Icc pins (IC has 2x Icc pins), in datasheet we can see that Icc max current is : 25mA  (is it per pin so 50mA max or total so 25mA max) 

In power supply recommendation we can see that we should be able to source 12*25mA =300mA => I am confuse can we really have Icc close to 300mA ?

We target to supply Vcc with +22.4V and Vss with 0V or with +/-12V, we want to be able to generate in both x16 channels voltage between range 0-20V or +/-10V with for each channels 10mA source&sink capability.

We will add in bottom an heatsink with a 4°C/W thermal resistance and 12 via that will connect a thermal pads of IC to a thermal areal of 4cm² in bottom under the heatsink.

I have tried added an heatsink with about 4°C/W under the thermal pads of the demo boad

I have load on 4x channels output 20mA totally => 80 mA from Icc

With a thermal camera I have measure on the top surface of the DAC for 4x first channels output at :

First 4x channels at 20V with 20mA load : 37°C

First 4x channels at 10V with 20mA load : 47°C

First 4x channels at 3.3V with 20mA load  : 56°C

Until I have not seen a thermal flag status, but if I try to load 1x channel at 45mA the thermal flag is set.

Thanks in advance for your support and best regards,

David DA SILVA

  • 0
    TI__Mastermind 46290 points
    David,

    The datasheet is describing the total current on the VCC and VSS nets - not any individual pin - given the top-line conditions described in the Electrical Characteristics table. Any further loading, will increase the current drawn from these nets.

    As long as thermal provisions are provided on the board, like the heat-sink you're describing, to keep the mentioned thermal shutdown risks at bay there is no issue with larger-than-typical currents flowing into VCC or VSS.
  • 0 in reply to Kevin Duke
    Prodigy 40 points
    Thanks to your reply Duke,

    Ok my mistake, so If I understand well as long as thermal shutdown didn't occur we should be able to source or sink current.

    For example a load of 30mA on both channels will increase Icc about : 30mA*16=480mA.

    Best regards,

    David
  • 0 in reply to David DA SILVA
    TI__Mastermind 46290 points
    David,

    That is correct.

    In fact, the reason we add multiple supply pins for the same net in many cases is in order to facilitate exactly this issue of providing larger currents than a typical low-power DAC application.