UCC28951: SR output timing

Charles Zhang1

Expert 3430 points

Part Number: UCC28951
Other Parts Discussed in Thread: UCC28950

Hi Team,

What's the timing between OUTE/OUTF, CS and DCM as listed below? Thanks.

(1)SR output turn-off propagation delay when CS<DCM

(2)SR output turn-on propagation delay when CS>DCM

Regards,

Charles

over 4 years ago

0 David Huang33 over 4 years ago

TI__Genius 9140 points

Hi Charles,

the post has been reassigned a an PSFB expert, will reply to you ASAP.

0 Mike O' over 4 years ago

TI__Guru* 86286 points

Hello,

Figure 2 of the data sheet shows the timing of OUT E and OUT F.

When the CS is below the DCM threshold these outputs are not driven.

Regards,

0 Charles Zhang1 over 4 years ago in reply to Mike O'

TI__Expert 3430 points

Hi Mike,

What's the delay time between CS going below DCM threshold and shutting off OUTE/OUTF?

Regards,

0 Mike O' over 4 years ago in reply to Charles Zhang1

TI__Guru* 86286 points

Hello,

There is an application note that discusses the UCC28950 at the following link. The control scheme is the same as the UCC28951. Please refer to figure 2 this will give you the timing of the E and F FETs with the input current of the transformer. This is more detailed than the data sheet and should help.

Regards,

Power management

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UCC28951: SR output timing