Charger IC BQ24092 Getting Heated Up

TI are generally pretty good, but make sure you read carefully through all the application notes for any info about layout, stability issues and heatsinking.
Look out for any of their test circuits too, as you can try them to check your circuit is performing the same way.
Check your input voltage isn't exceeding the rated maximum, if in doubt put a diode or two in series. (Check it's reasonably smooth too)
Measure the difference between Iin and Iout and Vin and Vout to see how much wattage is being dissipated.
Basically be methodical and measure everything, build a 2nd one and see if they are the same, maybe just as a birds nest rather than on a board, sometimes there is a pcb error which is overlooked. Two boards are better than one as it gives you some sort of comparison.
Good luck
Del

Thanks for the suggestion,

I will surely check this and update you the same.

regards,

Rimpul.

Dear Del,

I have calculated the power desipation,

In power=4.32W

out power=2.82W

So the desipation will be 1.52W

Details of current and voltage are as follows:

Iin=800mA

Iout=800mA

Vin=5.4v

Vout=3.50v

Regards,

Rimpul

It sounds like the charger IC is limiting the charge current because the IC temperature is too high. How is your PCB constructed? Do you have multiple vias in the center pad, tied to a large, unbroken copper area on the bottom of the board? What is the copper weight of your PCB? The TI recommendation is 2oz copper, with multiple small vias tying the thermal pad to a large copper area on the opposite side. Can you give some details of your PCB? A picture would be even better.

Tom D.

Thanks for the suggestion ..

1)yes, we have multiple vias in the center pad of the charger ic.

2)Copper weight is not 2oz but its less than .5oz

i am attaching the image of pcb board, pls check at the bottom right of the pcb board

Are the vias in the center pad tied to a full copper ground on the bottom side of the board? Is the center pad of the device completely soldered to the pad?

The resolution of the picture isn't really good enough to see what the board is like in that area, and of course does not show what the bottom looks like. Heavier copper would certainly help in this case, though without some kind of modeling, it's hard to say how much.

Tom D.

Battery must be rated at about 4.2 v. From the data sheet- it appears that you are drawing 800 mA at about 3.5 v or so. There is a Kset in the data sheet Aohm parameter. At the beginning (summary) it says input current limit is 500mA though title is 1 amp. Pl check design/ Check with User's guide / application notes.

As a quick test you could glue a couple of square inches of aluminium of copper sheet to the IC (epoxy or super glue would do it) and see if the charge rate comes up to spec. If it does then you know it's simply a heatsink issue.
Del

Check the condition of the battery if it is correct or incorrect and if defective replace it with a new battery because the battery is defective when it usually comes to overheating of the battery charger. if it is not the case check the charger circuit with integrated circuit and replace it with new.

Greetings Stojan Mitevski graduate engineer in electrical engineering

As I read your post and the answers, I can only shake my head. It's very painful to dissipate more than 400mW or so right on a PCB, especially if you aren't willing to devote a square-inch or more of board area for a huge copper pad. This is a linear regulator IC, which uses "thermal regulation" to maintain a charging current, creating T_J = 125°C. I mean, yes, man, that'll burn your finger! Shouldn't this be relied upon only for low charge currents like 100 to 250mA? You would like 600mA or more charging current, so wouldn't you be better off with a switching-regulator cell-charging IC? TI has some good choices. Maybe something like their bq24150A?