Auto-restart TNY 288 and TNY290PG
Hello!
I made 4 board with TNY288P, in 2 board TNY in auto-restart mode. How i can know what fault condition be ?
Pictures in appartment. Voltage: BP/M = 5.92V; EN/UV = 2.46V; D = 353V.
2 board work very nice, another 2 in auto-restart mode.
I tried TNY290PG in 2 board => the same thing auto-restart.
We want to launch these boards in a series of 3000 pcs. per month, so we need to understand this issue.
Files
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Comments
I made power source 24V 0.4A
Hi Raf329,
Thank you for your inquiry.
I'm not quite sure if I understand your problem. I assume that the parts on the 4 boards are all identical and the same? Which means they have the same schematic. 2 of the 4 boards are not working and in Auto-restart mode right?
What is the input voltage and the output load during the auto-restart?
Is it happening upon power up of the board? If you remove the load will it still auto-restart?
Regards,
PI-Picard
Hi, PI-Picard!
Yes, all board identical, 2 board in not work (TNY in auto-restart mode). Input voltage ~220V, 353V on D pin, output load ~ 0.1A. It is happening upon power up and always) - output voltage rise 4.8V and fall this period 2.5s If i remove load and keep on С6 - output voltage slow rise 21.62V and TNY auto-restart mode be.
Hi Raf329,
Can you first confirm that all values\parts are correct and the same between the working and failing boards? You need to do visual\physical check on the board.
If you are very sure nothing is wrong, including the transformer. Can you capture simultaneously in one screenshot the Drain waveform, BP, EN and Vout?
Regards,
PI-Picard
Hi, Pi-card!
Yes all the same. I dripped out with a working board transformer. => all the same auto-restar.
Picture in attachment V EN/UV = 2.42V. We see optocoupler not switch.
If i removed optocoupler => all the same auto-restart.
In datasheet write: "In the event of a fault condition such as output overload, output
short-circuit, or an open loop condition, TinySwitch-4 enters into
auto-restart operation." - If I shorted for 1 second output optocouper => all the same auto-restart. Output voltage slow rise until 21.52 with C6 and without load.
What reason auto-restart ?
1.Output Overload - no
2. Output short-circuit - no
3. Opne loop - no ?
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EN_UV.png | 948.8 KB |
Hi, Pi-card!
Yes all the same. I dripped out with a working board transformer. => all the same auto-restar.
Picture in attachment V EN/UV = 2.42V. We see optocoupler not switch.
If i removed optocoupler => all the same auto-restart.
In datasheet write: "In the event of a fault condition such as output overload, output
short-circuit, or an open loop condition, TinySwitch-4 enters into
auto-restart operation. If the ENABLE/UNDERVOLTAGE pin is not pulled low for 64 ms, the
power MOSFET switching is normally disabled for 2.5 seconds (except
in the case of line undervoltage condition, in which case it is disabled
until the condition is removed)." - If I shorted for 1 second output optocouper => all the same auto-restart. Output voltage slow rise until 21.52 with C6 and without load.
What reason auto-restart ?
1.Output Overload - no
2. Output short-circuit - no
3. Opne loop - no ?
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EN_UV.png | 948.8 KB |
Hi,
May I ask what do you want to know, the reason for the auto-restart as described in the datasheet or the faulty part on the board? Shorting the opto output will autorestart as it draws a large current from the EN pin.
Can you swap the optocoupler between the working and the faulty board?
Regards,
PI-Picard
Hi,PI-Picard!
I swap D4 P6KE200A between working and faulty board, and faulty board is excellent work)
But, i tested D4 from faulty board, with multimeter and he shows d4 correct?!
What can be? I hope in a series of boards this will not happen again.
Thanks you, for help)
Hi Raf329,
I don't quite seem to understand what you meant. Are you saying that the faulty part is the TVS diode D4?
1) Can you measure the drain voltage and drain current and compare between the faulty board and the working board? Look at the ringing and observe for any difference.
2) Can you insert a ferrite bead on the drain pin? - see if the autorestart is gone. Noise could getting coupled into the drain pin.
3) If after doing step 2 above, there is no more autorestart I would suggest that you need to modify the primary snubber clamp circuit.
Regards,
PI-Picard
Hi,PiCard!
2 faulty boards works 10 days and again entered in auto-restar mode.
In attachment schem and screenshot the Drain waveform.
Oscilloscope mode scan time 2us. Please help to understand this issue.
I have not ferrite beam for 600V.
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schem.png | 28.13 KB |
oscil Vd.png | 333.02 KB |
And in falling front Vd occurs before 0V???!!!!
In attachmentscreenshot the Drain waveform falling front.
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oscil Vd fall.png | 253.36 KB |
Hi,PiCard!
In attachment screenshot the Drain waveform working board.
Oscilloscope mode scan time 10us and 20us. Waveform Vdrain very difference.
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P_20171118_161918.jpg | 1.06 MB |
P_20171118_162005.jpg | 883.82 KB |
Hi Raf329,
Can you swap the Tinyswitch IC between the working and the faulty board? See what will happen.
Earlier, you mentioned that D4 was the one that caused the auto-restart? The problem could be in your primary snubber clamp. Please try inserting a ferrite bead on the Drain pin and see if it helps.
Let me know the result. Thanks.
Regards,
PI-Picard
my schem