AD8556: Offset-Settings vs. output gain / gain bandwidth


I am interested in using the AD8556.
In the data sheet there is no specification regarding offset settings.
- Especially I want to know the step size of output offset in respect to second stage gain.
- Likewise, what is the factor of DAC-value to the summing of output of first gain stage?
- What is the formula to calculate output offset voltage (to ground) when supply is 5V?

- for acheiving high bandwidth is it advisable to use higher gain in first stage and use lower gain in second stage (we need approximately G= 400)?

Also I want to know, for how long approximately this huge programming current will flow to blow one fuse?

All this needed info is missing in the dataq sheet!
I suppose that you revise it with that information.

  • 0
    •  Analog Employees 
    on Jul 23, 2019 7:03 AM

    Hi Alex,

    Here is the reply from the product owner.

    • Referring to the datasheet, equation (3) shows the output (VOUT) consists of the gained input which is biased by a VDAC voltage. The VDAC voltage is the offset adjust value.
    • The datasheet states the offset adjustment values in equation (2) in the Theory of operation. Where VDAC (the offset) is set by the 8 bit DAC code value which spans from VSS to VDD.
    • Use the first gain to set gain close to target and use second gain for finer adjust the gain to target gain.
    • About 1mS should be allowed for each fuse to be programmed.