LP8868V-Q1: Buck Boost

Mathanraj Pandian

Part Number: LP8868V-Q1

Tool/software:

Hi team,

My input voltage range is 9-16V, The typical voltage is13.5V,

If I drive the 1.5A LED 3 in series like I drive the 3 strings, how calculate the inductor value and you have tool to calculate the value. LED forward voltage drop is 3.5V

For LP8868Q1 the LT spice model is not available in your website,

Then How to calculate the power dissipation of IC ?

Can you provide the application notes of LP8868Q1 ..

2 days ago

+1 Suchen Dong 1 day ago

TI__Expert 3511 points

Hi Mathanraj,

7217.LP8868XY_encrypted.xlsx

For calculation, please refer to the datasheet. There are calculation examples in the datasheet (The calculation for LP8868V is the same as LP8868Y) .

You can also use this tool as a reference.

Best regards,

Suchen

0 Mathanraj Pandian 1 day ago in reply to Suchen Dong

Prodigy 30 points

Suchen Dong said:
r LP8868V is

But some issue with your calculation sheet

0 Suchen Dong 1 day ago in reply to Mathanraj Pandian

TI__Expert 3511 points

Hi Mathanraj,

Could you describe the issue?

Best regards,

Suchen

0 Mathanraj Pandian 1 day ago in reply to Suchen Dong

Prodigy 30 points

Hi Suchen Dong ,

Inductor calculation mismatching between application circuit and Calculation sheet...

0 Suchen Dong 1 day ago in reply to Mathanraj Pandian

TI__Expert 3511 points

Hi Mathanraj,

Could you explain more detailly?

The calculation sheet uses the estimated efficiency. The datasheet uses a fixed typical efficiency value.

0 Mathanraj Pandian 1 day ago in reply to Suchen Dong

Prodigy 30 points

If we calculate the inductor value through formula for same value is different from, I calculated through Calculation Tool, (I take the same value efficiency and Voltage, current

0 Suchen Dong 1 day ago in reply to Mathanraj Pandian

TI__Expert 3511 points

Is there any result could be shared? Is there a big different between them? Or they are just with errors?

Best regards

0 Mathanraj Pandian 9 hours ago in reply to Suchen Dong

Prodigy 30 points

Hi Suchen Dong,

In your calculation tools, I feed various input and output, inductor value still remains constant in 22 uH, For your reference I attached images.

Please check the calculation, inductor value change when the switching frequency changes, But in datasheet Formula, It depends on Input, output Voltages, Switching frequency.

Check and Clarify on this issue.........

0 Suchen Dong 24 minutes ago in reply to Mathanraj Pandian

TI__Expert 3511 points

Hi Mathanraj,

This is a normal design process. First you use all your design parameter to calculate a theoretical inductor value. However, actual inductor value options are limited in standard value. Hence, you should choose a near inductor value. The calculation sheet helps you do this. After selecting the actual inductor value. The other value (like inductor current) can be calculated then.

Best regards,

Suchen

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LP8868V-Q1: Buck Boost