TPS61169: Number of "LED strings" can this part drive in parallel

Mike Sprauve

Part Number: TPS61169
Other Parts Discussed in Thread: TPS61500, LM3410, TPS61500EVM-369

I have an application that requires drive upto 200 LEDs in a constant current mode, the voltage source is a single cell rechargeable LiPo battery. The "LED string" has the following parameters

LED Voltage drop ~1.67V to 2V

LED string current 15mA

Total number of LEDs 200

My questions are the following:

1. Is this part suitable or is there a more suitable part

2. What is the optimal number of LEDs per string

over 5 years ago

0 Charles-Chen over 5 years ago

TI__Genius 11836 points

Hi,

Proper engineer has been assigned to look at this and will reply to you soon.

0 Mike Sprauve over 5 years ago in reply to Charles-Chen

Intellectual 390 points

Hi Charles,

Do you know when this person is going to reach out to me... I need to move forward on my design

0 Sean Zhou over 5 years ago in reply to Mike Sprauve

TI__Mastermind 22745 points

Hi Mike,

What's your input voltage range? I can help to estimate the power level based on the application specs. The maximum output power is about 6W(10s20p), for low input voltage, it may trigger internal current limit.

Regards

Sean

0 Mike Sprauve over 5 years ago in reply to Sean Zhou

Intellectual 390 points

Hi Sean,

We are hoping to drive it off a single cell LiPo so the voltage range will the standard 3.7V - 3V. I hope that helps

0 Sean Zhou over 5 years ago in reply to Mike Sprauve

TI__Mastermind 22745 points

Hi Mike,

TPS61500 or LM3410 may be a good solution.

Regards

Sean

0 Mike Sprauve over 5 years ago in reply to Sean Zhou

Intellectual 390 points

Hi Sean,

I want to make sure my calculations/assumptions are correct

Circuit will have 20 parallel strings of 10 LEDs in series - Based on this configuration, Vout is ~20V
Current draw per string will be 15-20mA - This is based on the current draw requirements of one LED
Total current draw for the LED circuit will be 400mA (max) - This is based on 20 strings x 20mA per string
Total power for the circuit is ~8W - 400mA x 20V

My follow up question(s) are 1) Are my calculations/assumptions correct and 2) It seems that either device can handle the Vout (20V), Iout (400 mA) with an input voltage range of a single cell LiPo battery.

0 Sean Zhou over 5 years ago in reply to Mike Sprauve

TI__Mastermind 22745 points

Hi Mike,

Yes, your calculation is right, but for 20V with 0.4A, TPS61500 can support this kind of power. Or you can try with LM3410.

Regards

Sean

0 Mike Sprauve over 5 years ago in reply to Sean Zhou

Intellectual 390 points

Hi Sean,

Thank you very much and I have one more request, can you provide the altium design files for the TPS61500EVM-369 board that would be very helpful

0 Sean Zhou over 5 years ago in reply to Mike Sprauve

TI__Mastermind 22745 points

Hi Mike,

I'm sorry that we usually don't provide the altium files. Since this is simple, you can refer to EVM schematic, BOM and user guide for more detail layout information.

Regards

Sean

0 Mike Sprauve over 5 years ago in reply to Sean Zhou

Intellectual 390 points

Sean,

Thanks for all your help

Power management

Power management forum

TPS61169: Number of "LED strings" can this part drive in parallel