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Original question:

UCC256403: PMP40766 LLC based on UCC256403 constant output current mode

UCC256403: UCC256403 HV Function

Kami Huang60
Genius 3830 points
Part Number: UCC256403
Other Parts Discussed in Thread: UCC28019A

Dear Sir/Ms.

1. Integrated High Voltage Startup
Does it mean UCC256403 pin 1 (HV) be disconnected ? After disconnect, it starts to operate when VCC is supplied ?
Because of some past experience, the HV will start up periodically to affect standby power measurement (let me know if I am not correct ?).

2. External Bias Supply
What does it mean "requires external bias supply" to UCC256403 ?

Customer RD prone to design UCC256403 + UCC28019A in 120W x2 amplifier if the power supply proves quiet enough. Because customer have a 3V3/+-5V standby transformer, custmer can rectify a 15V to supply UCC256403 as customer want it work and connect the RVCC of UCC256403 to power up 28019A.

Best Regards,

Kami Huang

  • 0
    TI__Genius 9790 points

    Hi, Kami

    UCC256403 is one part of family of UCC25640X, The HV start up function is disabled in UCC256403, so HV pin of UCC256403 can be floating or short to GND. That is why UCC256403 need external bias supply to VCC of UCC256403.

    The RVCC of UCC256403 is 13V which is output of LDO from VCC to RVCC, so VCC should be connect to external bias supply of >13V.