NCP1246 ONSEMI [ON Semiconductor], NCP1246 Datasheet - Page 30

• Manufacturer Part Number: NCP1246
• Description: Fixed Frequency Current Mode Controller for Flyback Converters
• Manufacturer: ONSEMI [ON Semiconductor]

protection, an offset proportional to the input voltage is
added on the CS signal by turning on an internal current
source: by adding an external resistor in series between the
sense resistor and the CS pin, a voltage offset is created
across it by the current. The compensation can be adjusted
by changing the value of the resistor.
sense signal is small, i.e. in light load conditions, where it
To compensate this and have an accurate overpower
But this offset is unwanted to appear when the current
Figure 63. Needs for Line Compensation For True Overpower Protection
Figure 64. Overpower Protection Current Relation to Feedback Voltage
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NCP1246
30
would be in the same order of magnitude. Therefore the
compensation current is only added when the FB voltage is
higher than V
being connected to ac voltage, there is needed an additional
circuitry to read or at least closely estimate the actual voltage
on the bulk capacitor.
FB(OPCE)
. However, because the HV pin is