XTR111: Maximum Current Boost

Rodrigo Vernini

Part Number: XTR111

Hi,

i would like to know what's the maximum current boost using the schematic in the XTR111 datasheet.

At first i thought that it was limited just by the transistor gain and 5mA base, but i tested a 50mA power consuption with a MMBT3904 and the XTR111 burnt.

Now i'd like the confirmation that if it's ok to work with this current (the goal is 200mA), to make more tests.

Thanks

over 7 years ago

0 kai klaas69 over 7 years ago

Guru 140200 points

Hi Rodrigo,

see the absolute maximum ratings and footnote (4) of datasheet of XTR111:

"The IS pin current absolute maximum rating is +25mA and –50mA."

So, the absolute maximum current flowing out of the IS pin is 50mA.

Have you understood how the IS pin and the VG pin work together and what role plays Q2?

Kai

0 Rodrigo Vernini over 7 years ago in reply to kai klaas69

Intellectual 290 points

Hi Kai,

thanks for the reply.

See that my question is specifically about the current boost configuration Figure 49, and the maximum source current on the regulator voltage in that configuration. I think you're talking about the output. Sorry if i wasn't clear.

Rodrigo

0 kai klaas69 over 7 years ago in reply to Rodrigo Vernini

Guru 140200 points

Hi Rodrigo,

ah, sorry!

I would use the scheme in figure 45 (c) with the additional 1k base resistor.

Kai

0 Rodrigo Vernini over 7 years ago in reply to kai klaas69

Intellectual 290 points

The problem was the transistor. I tried with a TIP41 (TO-220) and it worked, but is getting very hot.

It was dissipating (34-3,3)*0,05 = 1,5W. My initial SOT-23 transistor couldn't deal with it.

0 Dennis Goeke over 7 years ago in reply to Rodrigo Vernini

TI__Genius 11135 points

Rodrigo

We haven't heard back from you so we assume you were able to resolve your issue. If you need additional help just post another reply below.

Thanks
Dennis

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XTR111: Maximum Current Boost