TPS923655: Can I use TPS923655 for following design

Tahrim Chowdhury

Prodigy 10 points

Part Number: TPS923655
Other Parts Discussed in Thread: TPS923622

Tool/software:

Vin: 48V

V-led: 60V

I-led: 2A and 4A

Can you please share part value calculator tools?
Is there way to modify the eval board to test out the LED panel(60V, 2A), beside the current sense resistor, what else I would need to change to get 60V output?
Can I also get design files for the eval board?

Do you have TI-TINA simulation file for the TPS923655?

Thank you.

over 1 year ago

0 Steven Li over 1 year ago

TI__Mastermind 23190 points

Hi Tahrim,

Here is the list of FAQs you can refer to - [FAQ] List of FAQs for TPS923655 / TPS923654 / TPS923653 / TPS923652 LED driver - Power management forum - Power management - TI E2E support forums.

TPS923655 may work in Vin = 48V, V_LED = 60V, I_OUT = 2A, but we do not recommend you do so for two reasons -

The 60V output voltage is too close to the Recommended Operating Conditions of the device.
You need to build additional external OVP circuitry to protect the IC in case of LED open failure. Please read this FAQ and see why the internal OVP circuitry cannot protect the IC in such a high-output-voltage condition - [FAQ] How to design the OVP resistor divider for TPS923655 / TPS923654 / TPS923653 / TPS923652? - Power management forum - Power management - TI E2E support forums

It is very hard and also not recommended for TPS923655 to work in Vin = 48V, V_LED = 60V, I_OUT = 4A mainly for three reasons -

Two reasons are the same as above.
Based on estimation, the temperature rise of the IC at this application condition is very high and may trigger thermal shutdown if no additional thermal relief methods are used.

You can find the preview version of the calculation tool (Excel spreadsheet) in this E2E FAQ - [FAQ] Is there a calculation tool for TPS923655 / TPS923654 / TPS923653 / TPS923652? - Power management forum - Power management - TI E2E support forums

We can send you the design files of the EVM through e-mail.

We do not have TI-TINA simulation file for this device. SIMPLIS model for this device is available upon request.

Best Regards,

Steven

0 Tahrim Chowdhury over 1 year ago in reply to Steven Li

Prodigy 10 points

Thank you Steven.
Can I use TPS923655 for
V_LED: 54V I_LED: 2.4A and
V_LED: 56V I_LED: 1.2A
Vin: 48V

0 Tahrim Chowdhury over 1 year ago in reply to Steven Li

Prodigy 10 points

If TPS923622 is not suitable, can you please recommend another TI part for this design.

0 Steven Li over 1 year ago in reply to Tahrim Chowdhury

TI__Mastermind 23190 points

Hi Tahrim,

It is possible for TPS923655 to work in those conditions. But you need to build additional external OVP circuitry to protect the IC in case of LED open failure.

Best Regards,

Steven

0 Tahrim Chowdhury 11 months ago in reply to Steven Li

Prodigy 10 points

Hello,

Do you mean circuitry to detect Open LED and set >1.45V at OVP pin?

What happens if the LED is open and OVP pin is at <1.1V?

Regards

Tahrim

0 Jared Zhou 11 months ago in reply to Tahrim Chowdhury

TI__Mastermind 20515 points

Hi Tahrim,

Our expert is OoO and he will reply to you once he is back to office, thanks for your patience.

BR, Jared

0 Steven Li 11 months ago in reply to Tahrim Chowdhury

TI__Mastermind 23190 points

Hi Tahrim,

Let me clarify with an example.

Let's assume you are going to work with Vin = 48V and V_LED = 56V, ILED = 1.2A. If you set the 1.1V threshold at output voltage = 57V (which is 1V larger than 56V), then when LED open load happens, in the worst case the circuit may stop switching when V_OVP = 1.45V, which means your output voltage goes up to 57 / 1.1 * 1.45V = 75.1V. This is beyond the absolute maximum ratings of the device and may cause permanent damage to the chip. Therefore, you need to build additional external OVP circuitry to protect the IC in case of LED open failure.

Best Regards,

Steven