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accuracy of peak current control in UC2625

Muhammet Cosan
Prodigy 30 points
Other Parts Discussed in Thread: UC2625

I am interested in finding out about the accuracy of the 2.5V and 3.1 V references inside the UC2625 motor control chip. The block diagram of the chip shows that there is a 2X gain amplified, an absolute value block, a 2.5 V and 3.1 V reference voltages.  The "current amp" section of the data sheet (sheet 4) states that the accuracy of 2x gain amplifier, abs value block and reference voltages all together add up to 30%, which is very high.  I would like to use an external gain amplifier but have to rely on internal voltage references, in which case I need to know the accuracy of 2.5 V and 3.1 V reference voltages. I dont expect the accuracy of the reference voltages being that high, but I need to know this in advance.

Thank you,

Muhammet

  • 0
    TI__Prodigy 20 points

    Unfortunately  the accuracy is undeterminable as the 2.5V voltage is developed with PN junctions and are temperature dependent.  So the 30% accuracy is taken over the temperature range of the controller giving an aggregate tolerance, the only way we could quantify a tolerance.  The best thing to do is to try to use an external reference if possible. 

  • 0 in reply to James Aliberti
    Prodigy 30 points

    Thank you James,

    I dont mind using an external reference. However, referring to the block diagram on page 6 of the data sheet, I dont see how an external reference voltage can be used.