IRAC27951SR IRS27951 Evaluation Board User Guide

5.3 IRS27951 DC Supply Voltage

The board is self-supplied by startup circuit and auxiliary winding of transformer. The startup circuit starts to work once AC or DC input voltage applies to the board. However, the Vcc will be stable only when BUS voltage is 350Vdc or above. The VCC voltage is monitored at test points VCC and COM.

5.4 Disconnect the Board

It is recommended to discharge the bulk capacitor C4 every time after evaluation is finished:

- Disconnect the high voltage AC or DC source from CON1

- Apply an external 12V DC voltage to primary Vcc and COM test points for a while until bus voltage drops to 0V

Rev. 4.1 6/1/2011 International Rectifier Page 11 of 23

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