TPS92692-Q1: Maximum power dissipation

Ross Parlour

Part Number: TPS92692-Q1

Tool/software:

Hi,

My customer is making a mock-up of a lamp, and is trying to find the maximum power that could be dissipated on the driver. They are using 9 LEDs with a maximum Vf of 2.75 and If of 0.7A. I took an efficiency rating from the data sheet and calculated the power dissipated from that, but it appears to be too high.

Do you know what the maximum power that can be dissipated on the driver is?

BR, Ross

6 months ago

0 Daniel Louis 6 months ago

TI__Expert 5690 points

what are your input/output requirements

0 Ross Parlour 6 months ago in reply to Daniel Louis

TI__Intellectual 1825 points

The input voltage range is 7V-16V and the output range is 16V-24.75V

0 Daniel Louis 6 months ago in reply to Ross Parlour

TI__Expert 5690 points

Hi Ross,

Your question is kind of nuanced as we do not have a maximum power rating for this chip. Rather, our concerns lie predominately with input current at low-line voltage (lowest input voltage) as this pertains to the maximum current going through the device and how much heat the board and its components will have to endure. We have flexibility with the maximum power because this device does not have integrated switching FETs, so the main bottleneck is the external components. If you want a general recommendation, I will need the output power your customer is trying to achieve as well as the intended end application.

I look forward to assisting you further.

Best,
Daniel

0 Ross Parlour 6 months ago in reply to Daniel Louis

TI__Intellectual 1825 points

Hi Daniel,

Yes please to the recommendation. At a maximum, they are looking at 17.325W across the LEDs. The application is Headlamp.

BR, Ross

+1 Daniel Louis 6 months ago in reply to Ross Parlour

TI__Expert 5690 points

17.325W is fine

0 Ross Parlour 6 months ago in reply to Daniel Louis

TI__Intellectual 1825 points

Okay that’s great thanks. Do you know roughly how much power they can expect to be dissipated on the driver if that is the value across the LEDs?

0 Daniel Louis 6 months ago in reply to Ross Parlour

TI__Expert 5690 points

Hi Ross,

We typically are more concerned with the current at "low-line" voltage (the lowest voltage accounted for at the input) as this is the point at which the current is the highest. I really need the power at the input in order to answer your question.

Furthermore, we are less concerned about how much power can be dissipated across the IC because we really just need to prevent the IC from reaching the absolute maximum temperature. So proper heat sinking should be the focus here.

The power dissipated across the IC can be calculated by by subtracting the power at the output from the power at the input.

Best,
Daniel Louis

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TPS92692-Q1: Maximum power dissipation