TLC5922: The Formula for Calculating Power Consumption

Hi Shinichi,

Nice to hear you.

For the power consumption, I guess they want to know how to calculate the temp rise of the device.

So, they can take bellow document as reference:

Semiconductor and IC Package Thermal Metrics (Rev. C) (ti.com)

Besides, this device is very old one, and we have many new devices also support 16 channels control, do they have some special requirement for TLC5922?

If not, I would like recommend you some new devices with better supply condition.

Thanks!

Ives Li

Hi Ives,

Thank you for your reply.

In this case, the customer'd like to calculate the power dissipation of the device.

The TLC5922 is a sink type LED driver.
Regarding the loss budget, I think as follows.

I'd like you to check and advise. 

・Pout 　Power of OUT pin　The value obtained by subtracting the VF of the LED from VLED is given to the OUT pin.
The value obtained by multiplying that value by the sink current is the loss.

(VLED-VF)×Isink
Multiply by the number of Ch.

Pout=(VLED-VF)×Isink x ch number

Apply duty according to usage conditions

・Consumption of the device itself
Supply voltage VCC multiplied by ICC.

Pdevice=VCCxICC

Ptotal＝Pout＋Pdevice

Please provide any application notes that illustrate power loss about sink type LED drivers.

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I appreciate your great help and cooperation.

Best regards,

Shinichi

Hi Shinichi,

Yes, your understand about power dissipation is correct.

But still need to pay attention on PCB layout, which plays an important role in temp rise.

Thanks!

Hi Ives,

Thank you for your reply.

You're right, I think the heat generation will change depending on the layout of the board.

I'll share the application note you attached and tell them to pay attention.

I appreciate your great help and cooperation.

Best regards,

Shinichi