This means if we want 5.00 volts output then we have to make sure we have 3.75 volts at the ADJ pin. The second spec is the voltage at the "ADJUST" terminal has to be equal to the desired output voltage minus 1.25 volts (approximate). Then there is a second 'spec' that we have to ensure gets satisfied. Note we dont have to mention any resistor values to understand that spec. The output must see a load current of 5ma out of the output terminal, period. It's a specification independent of everything else. It has almost nothing to do with the 240 ohm resistor. This is the minimum load talked about on the data sheet. The output of the regulator MUST be LOADED to at least 5ma (10ma for some versions, but lets assume 5ma for this discussion). Let me try to explain a little better here. For one thing, designs can be made without using a 240 ohm resistor. To start with, just forget about the 240 ohm resistor, forget about it completely for now. Lets see if we can clear this mystery up once and for all Sometimes people are so stupid they can't comprehend how stupid they are.Īnd they handed the LP2951A over to a green designer with the orders to get the A grade yield up to 90%. you don't like a part that generates $200 MILLION a year in profit because it also creates a million in scarp?"Īffirmative. I was at a meeting where the manager howled about how the LP2951A generated so much scrap. And scrap is one of the metrics every manager hated. It just forced them to open limits wider.īut sometimes when real A grade yield was high, it generated scrap because you had to build so many parts to get enough of the A's, some "C" grades were left unwanted (scrap).
In the old days, A grades were the "cherry parts" with tight specs that were reaped out of the center of the distributions. As I pointed out, that means there is NO MORE "A" GRADE. the new EDICT FROM GOD was that no new product could release unless the "A" grade yield was over 90%. at NS in the last years when the lunatics were completely running the asylum.