So you're saying they're actually identical?
Yes, but he also said they were essentially the same. When I said "identical" I meant in specs, not internals.
Btw: 400 mA drop-out compared to 250 mA of drop-out means 60% higher power dissipation at a minimum.
A = .607 / (Vin - Vout)Vout = 3.3v, so:.607 / (5 - 3.3) = .357 (Piggybacking off my 5A 5v regulator).607 / (8.4 - 3.3) = .119 (7.2v NiMh -> 8.4v at full charge).606 / (12 - 3.3) = .070 (12v battery - probably more like 13v+ but whatever).606 / (16 - 3.3) = .048 (16v worst case)
PD = IOUT * (VIN - VOUT) + VIN*IQ where VIN = input voltage; VOUT = output voltage; IOUT = output current, A; and IQ = quiescent current, AI assume quiescent current is also known as ground current as that seems to match up with the minumum quiescent current listed in the absolute maximum ratings and there's no other quiescent current listed. In which case for both vregs, it's 850uA typical at 150mA output. Which means as far as the power dissipation equation goes, the two regulators are identical.
Let me toss in a few ideas here. These last calculations are the most pertinent. They showyou are quite limited in how much current the v.regs can "realistically" supply, without meltingyour pcb. Assuming the NiMH cells are the most likely to be used, you've got ~120 mA max.HOWEVER, and it's a BIG however, you're allowing 150degC temp on the v.reg. How hot is that?100degC is the temp of boiling water, and how long could you keep your hand in boiling waterfor? 0.5 sec, that's it. IOW, you're really pushing it here.
Thirdly, for my part [and I've designed a lot of pcbs], I wouldn't even think about using such a tinysmt part at all, unless I was sure PD would always be maybe < 50% of your 0.6W value. Then the v.regwould not overheat so much, and it would still be a 75degC = 167degF on the part. Still prettydarn hot.
Fourthly, I don't even like the SOT223 parts [160degC/W], let alone the tiny ones you're using. Igo for the NCP1117 DPAKs [67 degC/W].
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