low-cost opamps in sot-23

Aug 20, 2019 8 Replies
W

I have received a respectable 2SK3018 MOSFET, made by Jiangsu Changjiang, from LCSC, only $0.0133 each. Now I'm looking for a low-cost opamp to go with it. Found the TP09, a 6MHz dual, from 3Peak, Vos 400uV, $0.06 each, looks fine, but would like a single type in a SOT-23 package. Picky, picky, picky!



Ah, the LMV321 in SOT-23-5, in stock at LCSC: TI: $0.0735, Diodes: $0.077, 3Peak: $0.05, Gainsil: $0.03. Or in SC-70, 3Peak: $0.059. So slow, only 1MHz. LMV321TP 1.3MHz upgrade.



Hey, 4MHz TP2262 by 3Peak, $0.132, but dual in sop8. Wait, sot-23 TP2261, oops, no stock.



Thanks, - Win
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W

I'm impressed with 3Peak, cool designs, and low prices! Their TP1561A is a single version of the TP09 in sc70 $0.083 (sot-23 a bit more). That's only $0.096 for opamp and MOSFET pair.

Thanks, - Win
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J

The really cheap amps are basically 5 volt parts. Is that enough gate drive?

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M

Have you any experience of buying (small and multi reel quantities) from LCSC ?

Certainly the prices look nice.

Thanks.

MK

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T

I don't have direct experience yet but I haven't heard anything bad about it from others. AFAIK, they have some QC so it's not like buying crap off Ali or eBay.

The tariffs going on right now stink, but it's still priced well below DK/Mouser.

Tim

Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website: https://www.seventransistorlabs.com/
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M

I'm in the UK - free trade with USA and China, here we come ! (I hope)

MK

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W

Yes, middle-level quantities, and a full reel once. I've found them very well organized and easy to work with. Sort of a Chinese Digi-Key. Low-cost shipping. I've been using DHL.

Thanks, - Win
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W

Yes, for modest currents. The 2SK3018 spec is 7 ohms with 2.5-voltage gate drive, and for linear operation Vgs = 2 volts at 25mA. Ciss = 13pF at Vds = 5V. I was attracted to the low capacitance. For higher currents, one will need a bigger logic-level MOSFET, and have to spend more than 1.3 cents. One problem, I can't think of any applications that really need the low cost. :o)

Thanks, - Win
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R

I can't think of any applications that need high cost. 8-o

Rick C. - Get 1,000 miles of free Supercharging - Tesla referral code - https://ts.la/richard11209
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