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Pin VGG function description on page 6 of the datasheet reads in part: "For VIN ± 4.75V, the internal VGG generator can be used. For VIN > 4.75 V, this pin should be driven from an external bias supply." I believe that this is supposed to say "For VIN > 4.75V, the internal VGG generator can be used. For VIN < 4.75 V, this pin should be driven from an external bias supply."
That is correct, this change is in process along with a change for the recommended resistor for the UCD7242 IMON pin which is currently specified at 10K ohms but should be 6.65K ohms to allow for the UCD92xx controller's default Fast OC Fault limit (150% rated current) to be set within the 2.0V upper limit of the DAC feeding the Fast OC comparator. A 9.53K ohm resistor can be used on IMON if the Fast OC Fault Limit of the controller is set to 0A, which disables the function and just rely on the HS current sense capability of the UCD7242 for fast OC limit protection, it will have a faster response than the controller in this case.
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In reply to Brad:
About the recomendation to replace the 10k resistor with 6.65k. For some reason we do not have a 6.65k in our system. Can I use a 6.81k or 6.19k instead?
In reply to Krister Lindstrom:
I would use the 6.19K this will allow the GUI generated default fault limit settings to fall within the operating range of the ADC and Fast OC comparator .
Just update the schematic section of the Fusion GUI Design page with the resistor value and make sure the check box for Current Sense in the Device Synchronization (also Design page), so that the correct values for the Current Sense Gain/Offset and the fault limits are updated when you perform a Write To Hardware (and Store To Flash if working with a live device).
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