hard wire lm3875 and heat on resistor

[imaginarytime]

Hey everybody.

I'm working on an lm3875 build that's held together by some protoboard, but basically hard wired (if that's what we call it.)

Anyway, I think I'm off to a cool start, but as I put it together, the resistor between pins 3 and 8 is going to be held to the chip. Seems that if the other side is going to be screwed to a heat sink, the resistor will be getting pretty hot.

This one's a carbon comp (those caddocks at ~$4.00 a pop might be worth it, but I need to hear the $0.50 alternative.) In particular an ohmite little demon. The data sheet doesn't mention anything about temperature tolerances in this context.

Are we worried about this?

[Robert Kesh]

Originally Posted by imaginarytime

Hey everybody.

I'm working on an lm3875 build that's held together by some protoboard, but basically hard wired (if that's what we call it.)

Anyway, I think I'm off to a cool start, but as I put it together, the resistor between pins 3 and 8 is going to be held to the chip. Seems that if the other side is going to be screwed to a heat sink, the resistor will be getting pretty hot.

This one's a carbon comp (those caddocks at ~$4.00 a pop might be worth it, but I need to hear the $0.50 alternative.) In particular an ohmite little demon. The data sheet doesn't mention anything about temperature tolerances in this context.

Are we worried about this?

Bake them, then measure their resistance. Or use something sensible. Or over rate the heat sink so it doesn't get hot.