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From: Jamie Morken on 8 Nov 2007 05:35

Hi,

For the TL499A: http://focus.ti.com/docs/prod/folders/print/tl499a.html

Is it possible to use this IC from a 1V to 30V input if the two inputs
pin1 "series IN1" and pin3 "SW reg in2" are tied together?

I have a working boost circuit from 1V to 30V input using the
LT1073:

http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1003,C1042,C1031,C1060,P1272

that IC is about 3 times the cost of the TL499A so am looking for a
cheaper alternative that can handle 1V to 30V input.

cheers,
Jamie

From: Jamie Morken on 8 Nov 2007 05:39
Jamie Morken wrote:
>
> Hi,
>
> For the TL499A: http://focus.ti.com/docs/prod/folders/print/tl499a.html
>
> Is it possible to use this IC from a 1V to 30V input if the two inputs
> pin1 "series IN1" and pin3 "SW reg in2" are tied together?
>
> I have a working boost circuit from 1V to 30V input using the
> LT1073:
>
> http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1003,C1042,C1031,C1060,P1272
>
>
> that IC is about 3 times the cost of the TL499A so am looking for a
> cheaper alternative that can handle 1V to 30V input.

The output voltage is fixed at about 27V (22V to 27V is fine)

>
> cheers,
> Jamie
>
From: ehsjr on 10 Nov 2007 19:42
Jamie Morken wrote:
>
> Hi,
>
> For the TL499A: http://focus.ti.com/docs/prod/folders/print/tl499a.html
>
> Is it possible to use this IC from a 1V to 30V input if the two inputs
> pin1 "series IN1" and pin3 "SW reg in2" are tied together?

No. There's a couple of problems. You want ~ 27 volts output. That
means you need 6 to 9V input at the switcher. Below 6V and you
won't get your ~27V out. Also, stuff 30V into the switcher and the
magic grey smoke will likely escape.

Ed

>
> I have a working boost circuit from 1V to 30V input using the
> LT1073:
>
> http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1003,C1042,C1031,C1060,P1272
>
>
> that IC is about 3 times the cost of the TL499A so am looking for a
> cheaper alternative that can handle 1V to 30V input.
>
> cheers,
> Jamie
>
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