• Resolved

LM48310SDBD_NOPB: LM48310 Breaking at high volumes

Prodigy 60 points

Replies: 7

Views: 106

Part Number: LM48310SDBD_NOPB

Hey guys,

I've been developing my own pcb that is a circuit comprising of the Teensy 3.2, Pjrc Prop shield, and Sparkfun 5v/1A boost converter (to power the Audio amplifier - LM48310).

I'm using the Teensy audio library to send audio to a single 4 Ohm speaker.

The problem I'm having is with my custom pcb, when i go over 0.7 gain with a saw wave at 160hz, the audio amplifier (or potentially the capacitors connected to it) shorts out and completely breaks. The circuit will only function again after i disconnect the broken amplifier , and until then the entire circuit is unresponsive. Everything works perfectly underneath a gain of 0.8, I have also tested full volume on the premade boards and it works without issue.

When the amp died after going up to 0.8 gain, I actually saw the board spark out of the corner of my eye , but I'm not sure exactly where the spark was, other that it was in the area of the audio amplifier.

The only thing I can think of is that my capacitors are placed incorrectly, and running high power through them is causing a short to happen through the air.

I'm attaching screenshots of my pcb design and schematic, if anyone can comment that would be an amazing help!
The board is 2 layers, with a ground pour on the bottom. The audio amplifier has a heat dissipating ground pour on the top layer too.

  • Hi, Ben,

    Welcome to E2E and thank you for your interest in our products!

    I will take a look at this and will answer as soon as possible.

    Best regards,
    Luis Fernando Rodríguez S.

  • In reply to Luis Fernando Rodriguez S.:

    Thank you Luis,

    I've been advised by the creator of the Pjrc prop shield that I should make my 4.7uf capacitor (c20) closer to the chip with small traces connecting it. Here's my updated design.

    Any other insight would be appreciated. :)

  • In reply to Ben Cooper1:

    Ben,

    Sorry for the delay on my response and thank you for your update.

    In addition, are C11, C12, C15 & C16 ceramic capacitors? We strongly recommend to avoid capacitors with polarity.

    The rest of the LM48310 schematic portion looks fine.

    Best regards,
    Luis Fernando Rodríguez S.

  • In reply to Luis Fernando Rodriguez S.:

    Hi, Ben,

    Do you have any update on this?

    Please, feel free to post your observations on this. We will be glad to assist you.

    Best regards,
    Luis Fernando Rodríguez S.

  • In reply to Luis Fernando Rodriguez S.:

    Hi Luis, sorry for the lack of reply.

    My capacitors are ceramic and without polarity.

    Ive ordered a new revison of my board with a better layout, which should arrive in the next few days.

    Ill test it and update you on the situation.

    Thanks again for your help!

  • In reply to Ben Cooper1:

    Hi, Ben,

    Thank you for your response. We will be waiting for your update.

    In the meantime, I will close this E2E thread. But please feel free to post your observations on this thread or in a new one in order to continue the support.

    Thank you.

    Best regards,
    Luis Fernando Rodríguez S.

  • In reply to Luis Fernando Rodriguez S.:

    Update:

    I found that the problem was the main capacitor, it was of low quality and only rated for 10v, which wasn't enough.

    Replaced with a higher quality capacitor and it works correctly now.

    I'm sure the layout change helped too.