Putting the 3255 in a case will hide it’s green LED. I’m thinking about relocating it to the front panel or leaving it alone and adding a new LED to the front panel. Any suggestions or warnings?
Got it from one of the sellers in Taobao. It was sold for $40 but the bummer was shipping cost at $37 which is fair enough for an item 12in D X 17in W X 4in H and weighing 6kgs 😀
😀😀😀 it does indeed 😀😀😀
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I would put the diode with the resistor to the power connectors. If an error occurs, you must open the box and check the FAULT and CLIP_OTW LEDs. Reason of fault is in table on datasheet. I think signal for FAULT and CLIP_OTW LEDs can use when you solder your LED with hole on board and Ground. They are located below Heat Sink. Please be careful, and first measure it!
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Can anybody give me a description how to implement PFFB - in easy/simple terms (best would be step by step guide) a not very well-informed member might grasp? Thx in advance.
You can place a 3 V LED across the # 4 (gnd) and # 8 hole (3.3 V supply) of the 28 hole double row interface socket (check the schematic on p 17).
Regards,
A Google search with "pffb tpa3255" gives you the TI document that describes what you need to do.
Thanks for the helpful suggestion - found the document in question, but I still have a question or two. I found those empty solder pads for most components needed to implemet PFFB but what about those parts which don't seem to have such a fixed spot (namely C_fb_in and _out and R_fb_gnd)? This is all pretty small below the board so I am a bit at a loss here. Any support will be greatly appreciated - thx in advance.
fault and clip leds
Hi,
Thanks to everyone here who inspired me to order a 3255EVM board, so far it sounds very good on the bench.
I am clear about how to wire up an external suspend/mute switch, and how to wire a power indicator led. I have a question about exporting some more functions of the J28 interface connector to an external panel.
If it's simple to do, I would also like to export the FAULT and CLIP_OTW active low pins to 2 more external leds. On the EVM board the 2 on board leds are driven from mosfets, the 12v and 3.3v rails and a bunch of resistors.
The clip and fault lines have internal pull-ups to 3.3v, apparently to reduce external component count - I don't know what that means or how many components are needed. I don't want to solder or desolder the EVM board directly.
I am wondering if there is a simpler circuit than the one implemented on the EVM. I wouldn't mind if the leds switched on, or switched off, to indicate fault conditions. My case has an auxiliary 12v supply available if it's any use.
I apologise that while I have some theoretical background in electronics I have a lot to learn, because I never got any practical experience until recently.
So if I can get away with (say) a simple resistor and led circuit it would be worth exporting these signals, but if it's going to involve transistors or a custom PCB I won't bother, I'll just have to squint inside the case.
Thanks.
Hi,
Thanks to everyone here who inspired me to order a 3255EVM board, so far it sounds very good on the bench.
I am clear about how to wire up an external suspend/mute switch, and how to wire a power indicator led. I have a question about exporting some more functions of the J28 interface connector to an external panel.
If it's simple to do, I would also like to export the FAULT and CLIP_OTW active low pins to 2 more external leds. On the EVM board the 2 on board leds are driven from mosfets, the 12v and 3.3v rails and a bunch of resistors.
The clip and fault lines have internal pull-ups to 3.3v, apparently to reduce external component count - I don't know what that means or how many components are needed. I don't want to solder or desolder the EVM board directly.
I am wondering if there is a simpler circuit than the one implemented on the EVM. I wouldn't mind if the leds switched on, or switched off, to indicate fault conditions. My case has an auxiliary 12v supply available if it's any use.
I apologise that while I have some theoretical background in electronics I have a lot to learn, because I never got any practical experience until recently.
So if I can get away with (say) a simple resistor and led circuit it would be worth exporting these signals, but if it's going to involve transistors or a custom PCB I won't bother, I'll just have to squint inside the case.
Thanks.
I too am interested in responses to the questions of Ytheleus above, but I’m also prepared to squint.
one method to bring the LED's out to the case would be a light pipe, i.e. small diameter acrylic or glass rod. Place it directly above the PCB mounted LED and route it to a viewing hole in the enclosure. No need to solder or add LED's, though affixing the light pipe brings about it's own issues.