Sujet : Re: Another design
De : invalid (at) *nospam* invalid.invalid (Edward Rawde)
Groupes : sci.electronics.designDate : 10. May 2024, 23:03:23
Autres entêtes
Organisation : BWH Usenet Archive (https://usenet.blueworldhosting.com)
Message-ID : <v1m22s$2qof$1@nnrp.usenet.blueworldhosting.com>
References : 1 2 3
User-Agent : Microsoft Outlook Express 6.00.2900.5931
"John Larkin" <
jjSNIPlarkin@highNONOlandtechnology.com> wrote in message
news:gnps3j99nl7t4dkdt22k7oe5tr0e6dh60i@4ax.com...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.
>
Ok here's the spec.
Input voltage range 10.5V to 12.6 V. Preferably 10V to 15V.
Minimum efficiency. 80%
Inductor not bigger than 68uH 1A. Preferably smaller.
One, two or three LEDs at 500mA +/- 50mA
Filtered LED feed referenced to ground.
Maximum total LED wiring length. 12 inches.
EMC compliant in all countries.
Cost. Minimum which will meet spec.