TPS923652:Adjustable LED driver current changing problem

Hasan ASLAN

Part Number: TPS923652

Tool/software:

Hello,
We designed a maximum 63V LED driver circuit that can be adjusted in the 0-2A range using TPS923652 LED driver (We used 20 of this circuit and will adjust 20 different LEDs). We made the circuit the same as TPS923655DRRRREVM. As I shared in the link below, our hardware friend asked you questions. (We have been interested in this project for 2 weeks). How can you support us technically? Our customer is waiting for this product. We tried everything such as adjusting the coil, shunt resistor and voltage divider resistors connected to the OVP pin, we use STEP mode and we are very familiar with the working principle. At first, we made adjustments according to 100mA and it worked stably, then we could not adjust it at all for the maximum current of 700mA. As the first step, we want you to help us with the values of the 0-700mA 0-36V circuit passives and in which mode we will use them.

TPS923652:Boost LED Driver

11 months ago

0 Steven Li 11 months ago

TI__Mastermind 23190 points

Hi Hasan,

What is your input voltage / output voltage (LED voltage) specification? Are you going to use boost or buck-boost topology with this device?

Best Regards,

Steven

0 Hasan ASLAN 11 months ago in reply to Steven Li

Prodigy 10 points

Hi Steven,

For example, we are using the input 12v output 36V Boost topology. The adjustable current range is 0-700mA. This example I gave is only valid for 1 LED driver and we are considering 20 different systems. It would be great if we could provide this example first.

0 Steven Li 11 months ago in reply to Hasan ASLAN

TI__Mastermind 23190 points

Hi Hasan,

Section 9.2 Typical Application from the datasheet contains lots of information to help you understand how to design the circuit for TPS92365x.

Here is a calculation tool for your reference - [FAQ] List of FAQs for TPS923655 / TPS923654 / TPS923653 / TPS923652 LED driver - Power management forum - Power management - TI E2E support forums.

Best Regards,

Steven

0 Hasan ASLAN 11 months ago in reply to Steven Li

Prodigy 10 points

Hello Steven,

We have reviewed the reference and all data sheets. If you can look back at my first question. You will understand that we have been working on this project for 2 weeks. Let's go through these steps please. We need definitive results and can you help?

0 Steven Li 11 months ago in reply to Hasan ASLAN

TI__Mastermind 23190 points

Hi Hasan,

Understood.

What is the exact problem you met? Do you mean you want to output 2A current with Vin = 12V, V_LED = 36V in boost topology, but you can just output 700mA (which is out of your expectation) at this moment with the above circuit?

Best Regards,

Steven

0 Hasan ASLAN 11 months ago in reply to Steven Li

Prodigy 10 points

Hi,

I can't adjust or change the output current. What I want to do right now is 12V input, 36V output and 700mA maximum output current. For this, can you give me information about what I need to do with the values of the components in the circuit above, or which components I need to change?

0 Steven Li 11 months ago in reply to Hasan ASLAN

TI__Mastermind 23190 points

Hi Hasan,

If you are going to use the above circuit for Vin = 12V, Vout = 36V, Iout = 700mA, then please refer to my comments below:

You had better adjust the current sense resistor (R152) as per your maximum current (700mA).
The inductor current ripple is too large. Please use inductor with larger inductance or use higher switching frequency.
SOT package will become very hot if you want a constant 700mA output and may lead to thermal shutdown / unwanted thermal foldback. Please consider using VSON / WSON package. Please also check your TEMP resistor setting accordingly.
C224 is too large.
Please check the current rating of the inductor.
The OVP resistor divider is not designed correctly. Please refer to this E2E FAQ - [FAQ] How to design the OVP resistor divider for TPS923655 / TPS923654 / TPS923653 / TPS923652? - Power management forum - Power management - TI E2E support forums
The Schottky diode is a bit overspec. You can consider changing it to a more appropriate one.

Best Regards,

Steven