BS2SX regulator,LT1121

Archiver

The LT1121can take up to 30V DC in. Does anyone have experience
running the VIN on the BS2SX at 14V? Does the LT1121 over heat?
thanks
SMS

Archiver

Here is an explanation of the proper input voltage applied to vin.

NOTE: When using battery or wall-pack power supplies, it is
recommended to limit the voltage to 9 volts on the Stamp 1 and Stamp
2, and 7.5 volts on the Stamp 2e and Stamp
2sx.

I think if you apply 14 volts and draw the maximum current from the
regulator you will definately run into thermal issues (Smoke!). There
isn't enough thermal mass in the BS2SX to dissipate that amount of
heat, meaning not enough copper left on the board to help dissipate
the heat. If you could attach a finned heatsink maybe .5" square
by .25" thick with thermal epoxy to the LT1121 package you might
squeze by.

If you look at the data sheet for the LT1121 there are formulas for
calculating the temp rise with Vin applied and output current.

Jason

--- In basicstamps@y..., "sms043" <sms043@y...> wrote:
> The LT1121can take up to 30V DC in. Does anyone have experience
> running the VIN on the BS2SX at 14V? Does the LT1121 over heat?
> thanks
> SMS

Archiver

Thanks,
--- In basicstamps@y..., "jbirnsch" <jbirnsch@v...> wrote:
> Here is an explanation of the proper input voltage applied to vin.
>
> NOTE: When using battery or wall-pack power supplies, it is
> recommended to limit the voltage to 9 volts on the Stamp 1 and Stamp
> 2, and 7.5 volts on the Stamp 2e and Stamp
> 2sx.
>
> I think if you apply 14 volts and draw the maximum current from the
> regulator you will definately run into thermal issues (Smoke!). There
> isn't enough thermal mass in the BS2SX to dissipate that amount of
> heat, meaning not enough copper left on the board to help dissipate
> the heat. If you could attach a finned heatsink maybe .5" square
> by .25" thick with thermal epoxy to the LT1121 package you might
> squeze by.
>
> If you look at the data sheet for the LT1121 there are formulas for
> calculating the temp rise with Vin applied and output current.
>
> Jason
>
> --- In basicstamps@y..., "sms043" <sms043@y...> wrote:
> > The LT1121can take up to 30V DC in. Does anyone have experience
> > running the VIN on the BS2SX at 14V? Does the LT1121 over heat?
> > thanks
> > SMS