DAC80508: Abs Max Current vs Output Current

Hi,

I don't think there is any issue with datasheet.

Specification says input current into any pin except power supplies ( Note specifically power supplies ).

Output current taken from supply pins, so this specification is valid.

Hope this clarifies.

Regards,

AK

Thanks AK,

So you would consider DAC sink current as output current? 

Don

Hi,

I agree on that point, DAC sink current is input current into output pin, that may be rectified in future revisions..

Thanks for pointing out.

Regards,

AK

Hey there,

My point is a little more involved.   Some bullet points:  

• TI specs abs max input current on every pin (except power) as -10mA (current flowing into of the pin - source) to +10mA (current flowing out of the pin - sink).    
• TI also specs the guaranteed DAC voltage headroom given DAC output current; specifically, -20mA (current flowing into the pin - sink) and +20mA (current flowing out of the pin - source).
• Note the inverted source/sink connotations given the input/output nature of each spec respectively.

Juxtaposing the first two bullet points would seem to indicate that the DAC80508 datasheet guarantees performance when operating beyond the abs max specifications.

Does that make sense?    

Don

Hi,

I think the first point is valid for both input and output pins, that's the reason it is written like that.

 For example SDO pin is output, -10mA is applicable for this, similarly for an input pin say SCLK, 10mA is an input current .

Anyway I will check with my design folks to clarify this. Even combining these two points, I am not convinced that TI guarantees performances when operating beyond max specifications.

For DAC Vout pin specifically, it can source and sink current up to +/-20mA with guaranteed headroom of 500mV.

Regards,

AK

Hey there,

Yes, I agree with you regarding the digital pins of the device.   Beyond +/-10mA is typically where ESD structures start popping.   Further, I agree with you that TI doesn't guarantee performance beyond the abs max ratings.   My statement was intended to illustrate the clear contradiction between the two separate statements in the datasheet.

I suspect that the abs max spec should probably read "Input into any pin except supply pins and OUTx pins".   If so, what's the abs-max current into the OUTx pins?

Don

Hi,

I agree with you Don.

It should be written as "Input into any pin except supply pins and OUTx pins ".

I will check with design docs, to get the abs max into OUTx pins. Likely it will be 35mA as the short circuit current when OUTx is shorted to VDD.

Regards,

AK