Motorola MC68008P10 current draw

[janoc]

Hello,

I am building a little retrocomputer for fun and the educational experience using a classic MC68008P10  chip in the 48pin DIP package. However, I was a bit surprised to see that the CPU draws about 170mA doing nothing - with just power and 4MHz clock hooked up. I can see it cycling through the address space, though.

Is 170mA normal for this chip? It seems to run a bit warm too - about 50 degrees C.  What are the normal, ballpark figures for this CPU? The maximum power dissipation in the datasheet is 1.5W, so at 5V it could potentially go up to 300mA, but still it seems a bit excessive to me.

I am wondering about it, because I had some issues on the board with a mis-wired 74LS245 bus driver causing a short and I want to be sure that I didn't blow the pin drivers on the CPU.

Regards,

Jan

[SeanB]

They do run toasty. I have done a mod on some older CPU's that ran very warm by using some thermal epoxy to fit a small DIP heatsink ( or for some 286 chips I was overclocking a little as big a heatsink as I could fit) to the top of the unit to drop the surface temperature by about 20C, which cooled them down a lot.

[janoc]

Ah, thanks for the info. I guess I am too used to the modern CMOS parts that take a few milliamps tops and run cool. However, I haven't seen heatsinks on these CPUs in any of the Amigas or Atari STs that used them, so I guess it could be OK.

I have even the larger MC68000 cousin in the ginormous DIP64 package (the largest DIP chip I have ever seen), but I haven't tested that one yet.

J.