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Date: Fri, 10 May 2024 18:20:39 -0400
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Subject: Re: Another design
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On 5/10/2024 5:06 PM, John Larkin wrote:
> On Fri, 10 May 2024 11:35:35 -0700, John Larkin
> <jjSNIPlarkin@highNONOlandtechnology.com> wrote:
> 
>> On Thu, 9 May 2024 23:11:03 -0400, "Edward Rawde"
>> <invalid@invalid.invalid> wrote:
>>
>>> "Edward Rawde" <invalid@invalid.invalid> wrote in message
>>> news:v1ho21$4ps$1@nnrp.usenet.blueworldhosting.com...
>>>> Now with 9V to 15V input range, direct gate drive and 500mA LED current.
>>>>
>>>> Startup behaviour is not ideal but maybe that can be fixed if it needs
>>>> fixing.
>>>>
>>>> What's the cheapest op amp I can use for U2 instead of OP07?
>>>>
>>>> Is there a cheaper comparator instead of LT1719 which will work?
>>>> Also the fet is bigger than it needs to ne.
>>>>
>>>> Is there a better device for D4? Particularly if R4 can be reduced.
>>>>
>>>> Will it work at all? Except in simulation.
>>>>
>>>
>>> I think I've answered my own question for the current controller but I don't
>>> think it's feasible to attempt a discrete comparator on cost grounds.
>>
>> I think the LED constant-current switcher can be done with a pfet and
>> two NPN transistors.
> 
> That's overkill. A pfet and one NPN might work.
> 

Speaking of overkill, wrt our previous discussion you might be 
interested in this mixed-signal array that has 8(!) LDOs on board:

<https://www.renesas.com/us/en/products/power-management/multi-channel-power-management-ics-pmics/slg51000-high-psrr-low-noise-multi-output-ldo-ic-advanced-camera-and-sensor-systems#overview>