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AD5560 Current Clamps accuracy

Thread Summary

The user inquires about the AD5560 current clamp accuracy and range. Without using offset (CLH, CLL), the current range is symmetrical. The clamp circuit has an inherent inaccuracy, with measured values deviating by up to 10% of the full-scale current. To improve accuracy, the user can adjust the CLH DAC m, CLH DAC c, CLL DAC m, and CLL DAC c registers.
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Hello,

I have some quetions about current clamps AD5560.

1) If i do not use offset (CLH, CLL), it is  mean that current range is simmetrical (for example -500 mA to 500 mA)

2) I use current range -25...25 mA, then i set CLH 18,75 mA - measuring value is ~ 21 mA, CLL -18,75 mA -measuring value is ~ -20,6 mA. For other points i have the same offset current (for every current range). Is it correct?  How can I set current clamp more accuracy? By using register CLL DAC c, CLL DAC m, CLH DAC c, CLH DAC m?

3) What is the minimum current limit value? + 10% of full-scale current (according with datasheet  DUT current can never exceed the programmed clamp limit + 10% of full-scale current)?

Thank you.

Edit Notes

changed CLL, CLH values
[edited by: Vladimir ALEX at 11:05 AM (GMT 0) on 11 Feb 2020]

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  • Hi ,

    First of all, I would like to apologize for replying this late and thank you as well for showing interest in AD5560.

    Moving on to your first question, may I know what you meant by offset (CLH, CLL)?

    For your second question, I've added a screenshot from AD5560 datasheet as a reference.

    From here, we can say that the clamp circuit is not that accurate. Since you set CLH = 18.75mA and CLL = -18.75mA and current range to ±25mA, once the current is clamped it is expected to get a value from ±18.75mA (programmed clamp value) up to ±21.25mA (±18.75mA + 10% of FS which is ±2.5mA). You may refer to the table below.

    With this, we can conclude that AD5560 still meets what’s in the datasheet. Additionally, there’s a chance to improve the clamp accuracy by using the CLH DAC m, CLH DAC c, CLL DAC m, and CLL DAC c.

    Best Regards,

    DJ

  • Hi DJ

    How one set of CLH DAC m, CLH DAC c, CLL DAC m, and CLL DAC c mapping to all current ranges?

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