<div class="gmail_quote"><div>Long time lurker, first time poster...</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">Leo Bodnar brought a good point to my attention yesterday. While the<br>
UL2803 can indeed handle 500mA per channel max, that's not what the<br>
devices as a whole can sustain.<br>
<br>
I never thought to check, but the part has a max draw per channel of about<br>
150mA if you're driving all 8 at the same time. The Toshiba datasheet for<br>
the part I'm using states a max dissipation of 1.47W. At 5 volts, that's<br>
only 294mA. At the voltage I want to drive it at (24vDC), it's less than<br>
100mA.<br></blockquote><div><br></div><div>I've looked at the datasheet for ULN2803AP, because I assume that's the one you're using. 1.47W is stated in the 'Maximum ratings', what most manufacturers would call 'Absolute maximum'. I would not suggest using that figure for calculating normal operational conditions. It will fail if used at max rating, just not right away.</div>
<div><br></div><div>Also, I think you're using Vce when calculating power dissipation. Remember to use Vce(sat) instead.</div><div> </div><div>...</div><div><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Just about every<br>
single digital output board that I've ever seen has _never_ mentioned this<br>
limitation.<br></blockquote><div> </div><div>Same observation here...</div><div><br></div><div>Back to my hole!</div><div><br></div><div>BR,</div><div>Per E</div><div><br></div></div>