BQ24192I: IC heating up

Nir Dvash1

Part Number: BQ24192I
Other Parts Discussed in Thread: BQ25892, BQ24192, BQ25731

Guys,

When using the BQ24192L to charge our battery with an input voltage of 15V and input current of 0.75A (that's about 12W of power), we measure about

80 degrees Celsius on the IC surface and about 70 degrees on the bottom side of the PCB where the chip is located.

This seems very high and I wanted to check this with you:

1. Is this normal?

2. Is there anything we can do to dissipate this heat beyond the PCB heat dissipation?

Please note that we wish to charge our large (50Ah) battery as fast as possible and so are looking to utilize the IC's current

I am attaching a paste from our PCB editing file so you can have a quick look at the layout of the IC.

Thank you,

Nir

over 4 years ago

0 Ning T over 4 years ago

TI__Guru 57861 points

Nir,

1.The IC power dissipation is related to the efficiency.
2.The IC temperature is heavily dependent on the PCB layout. A normal 4-layer PCB could have ~35Deg/W thermal resistance. Less than 4-layer board will be worse.
3. It is critical that the exposed power pad on the backside of the IC package be soldered to the PCB ground. Please nsure that there are sufficient thermal vias (9 vias) directly under the IC, connecting to the ground plane on the other layers. Please check if the exposed pad is soldered down correctly. Please refer to 12 Layout and Figure 52. Layout Example Diagram on the d/s for the details

Thanks,

Ning.

0 Nir Dvash1 over 4 years ago in reply to Ning T

Intellectual 470 points

Hey Ning,

Thank you. Assuming we have followed all of these recommendations, I am asking if 80 degrees Celsius is a normal temperature for the IC to be working in?

Nir.

0 Ning T over 4 years ago in reply to Nir Dvash1

TI__Guru 57861 points

Nir,

Please estimate the IC power dissipation (Pic) based on the efficiency measured. Assuming 35Deg/W thermal resistance, Tj=Ta + 35 x Pic. The calculation should give you a rough idea.

Thanks,

Ning.

0 Nir Dvash1 over 4 years ago in reply to Ning T

Intellectual 470 points

Hey Ning,

Since our charging current is at the high end of this IC capability, could you recommend another charging IC from your line that has similar properties as this one but can easily withstand a higher (double?) charging current and so will not heat up as this one does?

Thank you,

Nir.

0 Ning T over 4 years ago in reply to Nir Dvash1

TI__Guru 57861 points

Nir,

Please try BQ25892.

Thanks,

Ning.

0 Nir Dvash1 over 4 years ago in reply to Ning T

Intellectual 470 points

Hey Ning,

Thank you, but the BQ25892 is very close to the BQ24192 in terms of charging current (5A / 4.5A). I am looking for

a device which can charge a battery in 4A or 5A and will not get hot like the BQ24192 does.

Nir.

0 Ning T over 4 years ago in reply to Nir Dvash1

TI__Guru 57861 points

Nir,

The Rdson values for the BQ25892 internal MOSFETs are smaller than that of the BQ24192. So the efficiency of the BQ25892 has been improved. Please feel free to evaluate the BQ25892 and compare to the BQ24192.

Thanks,

Ning.

0 Nir Dvash1 over 4 years ago in reply to Ning T

Intellectual 470 points

Thank you Ning. I have looked into the D/S of both devices and found the following:

The typical Ron for BATFET has been reduced from 12mOhm to 11mOhm on the BQ25892.

The typical Ron for LSFET has been reduced from 32mOhm to 16mOhm on the BQ25892.

As I understand it, the BATFET is the one carrying the load while charging and if this is correct than the improvement you are referring to is of 1mOhm?

Please correct me if I'm wrong.

Nir.

0 Nir Dvash1 over 4 years ago in reply to Ning T

Intellectual 470 points

Also, what about the BQ25731?

Nir

0 Ning T over 4 years ago in reply to Nir Dvash1

TI__Guru 57861 points

Looping in Tiger to support BQ25731 questions. Thanks!

0 Ning T over 4 years ago in reply to Ning T

TI__Guru 57861 points

Nir,

BQ25731 is a different type of charger. Please submit a new e2e inquiry for BQ25731 questions. This thread is considered as resolved and closed.

Thanks,

Ning.

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BQ24192I: IC heating up