UCC25630-1EVM-291: OVP Latch, overcurrent,power on

Hiroshi Doi35

Part Number: UCC25630-1EVM-291
Other Parts Discussed in Thread: PMP21098

Hi all,

My customer have some questions. please ans. below.

1. To latch stop the LLC by output over voltage protection signal,
Is it necessary to latch by pulling up from Vcc instead of RVCC?

2. Do you have next OVP Latch IC version plan?

3. During the over current protection operation, the burst operation is performed at intervals of about 1 second,
What is the condition that determines this cycle?

4. When AC is applied, the Vcc terminal voltage repeats charging and discharging at a cycle of about 5 seconds
Is this cycle dependent on the charging setting current value by the internal constant current circuit?

Thanks!

over 7 years ago

0 Bosheng Sun over 7 years ago

TI__Expert 7310 points

Hi,

1, you can latch LLC by pulling down BLK or FB pin to ground. Do not pull down VCC or RVCC, this will damage the chip.

2, yes, but not in the near future

3, the device will restart after 1s after fault shut down

4, yes, also depends on the capacitance on VCC pin. VCC will be charged to about 26V.

Regards,

Bosheng

0 Hiroshi Doi35 over 7 years ago in reply to Bosheng Sun

Expert 2845 points

for 1.

There seems no keep latch method to FB pin to GND without external signal.

Without no use signal outside, secondary voltage becomes to all 0V, how to keep FB pin to GND?

OVP Latch and should be keep before AC restart.

Please show me your cct. without no use secondary cct.

Thhank you,

0 Bosheng Sun over 7 years ago in reply to Hiroshi Doi35

TI__Expert 7310 points

Hi,

Please check the schematic of TI reference design PMP21098, it has an external latch circuit.

www.ti.com/.../PMP21098

Regards,
Bosheng

0 Hiroshi Doi35 over 7 years ago in reply to Bosheng Sun

Expert 2845 points

Hi,
No need external latch cct.
I do not need Latch cct. with using secondary anything.
Once ovp worked, no secondary voltage alive.
The cct. have to keep ovp latch by using only primary cct.

0 Bosheng Sun over 7 years ago in reply to Hiroshi Doi35

TI__Expert 7310 points

The latch circuit in PMP21098 is latched on primary side, secondary just provide a trigger once OVP occur, after that there is no need for secondary any more.

0 Hiroshi Doi35 over 7 years ago in reply to Bosheng Sun

Expert 2845 points

Bosheng-san,

Thank you for your advice.

But here is Japan not China. All valuation have to consider.

RVCC under voltage lock out voltage spec shows only typ. spec = 7V.

If you cannot show min. spec of this, no confidence of D206 6.2V zenner. value.

Please show me min. spec.

Many of your members know my mail.

Thank you,

Power management

Power management forum

UCC25630-1EVM-291: OVP Latch, overcurrent,power on