LM3448 Output power

Oleksiy Pazyuk

According to the Power Management guide (http://www.ti.com/litv/pdf/slvt145l) LM3448 is intend to use in application below 8W.

From another side in the datasheet (http://www.ti.com/litv/pdf/snosb51b) there is no direct parameter which prove this. Indeed we have integrated FET with breakdown voltage 600V and maximum peak current 1.2A thus even if we will use the FET at values equal 75% we obtain FET power capability 400W.

Thus I guess the main limited factor will be power dissipation of the package but this parameters is not mention in the datasheet.

Could somebody clarify what parameter exactly limit output power of the LM3448 for values below 8W?

best regards,

Oleksiy

over 12 years ago

0 Vikram Sundaram over 12 years ago

Prodigy 10 points

Hello,

Im a student trying to learn through a LM3448 230v.6W evaluation board.

It was indicated in the datasheet http://www.ti.com/lit/an/snoa555b/snoa555b.pdf that the implementation included a Retrofit TRIAC dimmer

The datasheet also displayed the circuit operation using a forward phase TRIAC dimmer.
It would be of great help if someone could post the Prototype circuit of the Forward Phase TRIAC dimmer used.

Thank you,

Best Regards,

Vikram

0 Mike Kosteva over 12 years ago in reply to Vikram Sundaram

TI__Intellectual 2590 points

I'm getting a part number for you

0 Mike Kosteva over 12 years ago in reply to Mike Kosteva

TI__Intellectual 2590 points

Try getting the Clipsal KB31RD400 dimmer to work with

0 Vikram Sundaram over 12 years ago in reply to Mike Kosteva

Prodigy 10 points

Thank you ever so much mike.

0 Oleksiy Pazyuk over 11 years ago

Expert 2585 points

Could somebody clarify the question with LM3448 output power? I don't see direct answer it the datasheet.

What we have in data sheet whichcould give as the draft answer is the maximum Junction Temperature (TJ-MAX)=125C and THERMAL RESISTANCE (RθJA Junction to Ambient) 95C/W.

According to this if we make assumtio that we have overheating 75C we obtain PD-MAX = (75C) / (95C/W) = 0.78W.

0.78W is far away from 8W application.

May be I miss something, than correct me please,

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LM3448 Output power