TPS61169: TPS61169 IR LED Driver

jvasanthan

Intellectual 385 points

Part Number: TPS61169
Other Parts Discussed in Thread: TPS61166

Hi Team,

We are planning to use TPS61169 for driving 4 high power IR LEDS. The configuration is as below,

1. 4 IR LED will be connected in series - 1 String

2. VIN is 4.2V. TPS61169 will be programmed for 6.5V/400mA.

3. The Vf for the LED @ 400mA is 1.5V

As per datasheet, When TPS61169 is in shutdown mode there will be current flow through the inductor and diode.

1. With the above mentioned LED setup will TPS61169 enter into complete shutdown mode?

2. Does TPS61169 current control even in shutdown mode?

over 3 years ago

0 Yuting Shao over 3 years ago

TI__Genius 13001 points

Hi,

When device goes into shutdown mode, there will be about 4V output voltage which may cause current flowing through series LEDs. But, we can't make sure that there is current or how much it is due to LED characteristics variation.

When in shutdown state, the output current is only depends on the series LEDs and device can't control this.

Robin

0 jvasanthan over 3 years ago in reply to Yuting Shao

Intellectual 385 points

Our application is battery powered. The total LED Vf is 6V and the VIN is max 4.2V. Do you expect current flow in shutdown state? If so what driver do you recommend for battery powered applications?

0 Yuting Shao over 3 years ago in reply to jvasanthan

TI__Genius 13001 points

Hi,

Can you please provide the LED datasheet? Then we can be clear to the impact.

Robin

0 jvasanthan over 3 years ago in reply to Yuting Shao

Intellectual 385 points

Hi Robin,

How can I share the datasheet privately to you?

0 Yuting Shao over 3 years ago in reply to jvasanthan

TI__Genius 13001 points

Hi,

I'll request friendship from you on this forum.

BR,

Robin

0 jvasanthan over 3 years ago in reply to Yuting Shao

Intellectual 385 points

Hi Robin,

Yes I received the request and I have shared the datasheet as well

0 Yuting Shao over 3 years ago in reply to jvasanthan

TI__Genius 13001 points

Hi,

Got it.

Robin

0 Yuting Shao over 3 years ago in reply to jvasanthan

TI__Genius 13001 points

Hi,

According to the I/V curve of this IR LED, there is still current while TPS61169is shut-down.

TPS61166 has high side switch which provides input-to-output isolation during IC shutdown. Please refer to it.

BR,

Robin

0 jvasanthan over 3 years ago in reply to Yuting Shao

Intellectual 385 points

Hi Robin,

Few questions on TPS61166,

1. The datasheet says "IC Supply Range: 2.5-V to 6-V & Power Stage Input Range: 4.5-V to 10-V". What is the difference between IC supply range & Power Stage input range?

2. Does TPS61166 sets VOUT based on the led Vf and voltage drop across the current limiting resistor? we don't have to set it right?

3. What is the max LED drive current of TPS61166? can I set current to 700mA?

0 Yuting Shao over 3 years ago in reply to jvasanthan

TI__Genius 13001 points

Hi,

For your questions:

1.VIN pin is the IC supply and VBAT is the power stage supply. If you use one cell LI-ion battery, you can tie these two pins together and the input voltage range should be 2.5V-6V. If you use two cell Li-ion batteries, then you must separate these two pins, batteries are connected to VBAT and another power line is connected to VIN, because VIN range is 2.5V-6V while VBAT range is 4.5V-10V.

2.Yes, you're right.

3.You can calculate the average MOSFET current based on IIN=VOUTxIOUT/VIN, then add half of current ripple to IIN to get peak current IPEAK. The internal MOSFET current limit is 1.1A, so IPEAK must be lower than 1A.

BR,

Robin

0 jvasanthan over 3 years ago in reply to Yuting Shao

Intellectual 385 points

Thank you Robin

0 jvasanthan over 3 years ago in reply to jvasanthan

Intellectual 385 points

Hi Robin,

I coudn't find TPS61166 model in TI-Pspice. Could you please share TPS61166 TI-Pspice project files. I would like to simulate before freezing the design.

0 Yuting Shao over 3 years ago in reply to jvasanthan

TI__Genius 13001 points

Hi,

I'm sorry that I don't have its simulation model either. You can request an EVM to verify your design.

Robin

0 jvasanthan over 3 years ago in reply to Yuting Shao

Intellectual 385 points

Hi Robin,

TPS61166 is an old chip. is it active and recommended for new designs.

Just to confirm, driving 4 leds in series with 6V combined Vf @ 400mA is workable with TPS61166 right?

0 jvasanthan over 3 years ago in reply to jvasanthan

Intellectual 385 points

Hi Robin,

Just to add to my above question. Are there any other chip you think will be more suitable to our use case? Please recommend.

0 Yuting Shao over 3 years ago in reply to jvasanthan

TI__Genius 13001 points

Hi,

There are lots of devices with a history of many years and they all get well maintenance. So you needn't worry about this.

I think this device is a proper device and many customers still use it.

Robin

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TPS61169: TPS61169 IR LED Driver