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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 13th Apr 2019, 3:20 pm   #1
60 oldjohn
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Default SMD Voltage Regulator

I need three SMD voltage regulators 3v - 3.3v output 30ma min output, 20v min input. Anyone know what device number I need ?


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Old 13th Apr 2019, 3:24 pm   #2
paulsherwin
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Default Re: SMD Voltage Regulator

https://www.mouser.co.uk/Semiconduct...z0shyuZ1z0wd7g
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Old 13th Apr 2019, 3:55 pm   #3
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Default Re: SMD Voltage Regulator

Holtek 7550 are my go to. They have 24V max input. Don’t forget bypassing heavily according to the data sheet or they turn into oscillators.

LCSC sell cheap clone ones as well for virtually nothing.
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Old 13th Apr 2019, 4:39 pm   #4
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Default Re: SMD Voltage Regulator

Are there any 7550 devices that output 3-3.3v to keep component count down?
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Old 13th Apr 2019, 8:24 pm   #5
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Default Re: SMD Voltage Regulator

Yes they do fixed 3.3V version: HT7533-1
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Old 13th Apr 2019, 8:28 pm   #6
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Default Re: SMD Voltage Regulator

If you're inputting 20+ V and outputting 3(.3)V, remember to allow for the dissipation if the load is more than a few mA!
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Old 13th Apr 2019, 8:46 pm   #7
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Default Re: SMD Voltage Regulator

Good point. Based on facts here, over half a watt will need to be shifted. 7550 ruled out.
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Old 13th Apr 2019, 10:24 pm   #8
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Default Re: SMD Voltage Regulator

Exact values 14v (12v Car) to 3.3v @ 22ma. Original posting allowed a little head room. There are 12v max input versions of regulators that I would not expect to last very long in this application.


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Old 13th Apr 2019, 10:54 pm   #9
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Default Re: SMD Voltage Regulator

LM1117-3.3 a bit old hat but very widely available for trivial money in SMD. ISTR absolute max 20V, recomended max 15V, so may be on thin ice. An appropriate input dissipation burden resistor and quality decoupler will help to catch automotive spikes too, but I always feel that if you're not an exacting car industry bean-counter, then it's worth going OTT with all the spike-catching you can muster here- Rs, Ls, Cs diodes, MOVs etc, less than the cost of a pint will give peace of mind in this respect!
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Old 14th Apr 2019, 1:21 am   #10
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Default Re: SMD Voltage Regulator

TLV70233QDBVRQ1

Automotive voltage regulator 3.3v, not expensive - 59c US from Mouser
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Old 14th Apr 2019, 11:09 am   #11
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Default Re: SMD Voltage Regulator

If you add some series resistance in the protection/decoupling ahead of the regulator you can shift most of the dissipation to that, especially if load is fairly constant.

A bit questionable, but very handy in units operating in high magnetic fields before MHz switchers that could use air cored inductors came along.
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