Question of TPS61196

Hi,
Yes, TPS61196 can meet your application. And LP8860-Q1 also meets those condition and LP8860-Q1 is the four channel devices,
Regards
Sean

Thank you for your answer!

In datasheet, LP8860-Q1 can change the current limit by resister.
Please tell us the current limit of TPS61196.

Best regards,


Takahiro Nishizawa

Hi,
TPS61196 is the controller, the current limit was determined by the "ISENS" pin. I_limmit=V_ISET/R_ISET. R_ISER is the resistor connected to the "ISENS" pin.
Regards
Sean

Thank you for your answer!

We have new questions about TPS61196 and LP8860-Q1.

Question 1.
We want to make VF variation between channels ±2% or less.
Can these IC meet this condition?

Question 2.
We need the error detection when LED lights go out.
Do these IC have both of LED short detection and LED open detection?

Question 3.
We want to keep the LED on continuously when this detects LED errors.
Can these IC meet this condition?

Question 4.
We need PWM dimming 1kHz.
Can these IC meet this condition?

Best regards,


Takahiro Nishizawa

Hi Takahiro,

     Question1: what's your meaning about VF? is that mean the voltage on each channel? Because all the channels were connected to the output of the boost stage. They have the same voltage. Due to the different forward voltage of LED, our backlight driver will adjust the current sink voltage to meet the voltage drop.

    Question 2:Yes, both TPS61196 and LP8860 has the LED short and LED open detection function;

    Question 3:You can refer to the datasheet for detail description. usually when it detects open or short, it will remove the correspond channel from the system;

    Question 4:Yes, both can support 1kHz dimming frequency.

Regards

Sean

Thank you for your answer!


VF means output voltage.
We need accuracy ±2% about output voltage per ch.
Can this IC meet this condition?

About Question 3,
We find datasheet p.18 Table 2.
Plase tell us your answers.


Please tell us the difference about OPEN protections.

- Diode open
- LED string open(Result : LED string off = LEDs go out when is open condition? )
- All LED strings open during start-up


Please tell us the difference about SHORT protections.
- Diode shot
- LED string short during start-up
- LED short(Result : LED string off = LEDs go out when is open condition? )
- IFB short to GND
- ISET short to GND(Result : All LED string off = LEDs go out when is open condition? )


Please tell us the recover operation from latched off.


Best regards,


Takahiro Nishizawa

Hi
The voltage for each channel is keep same, the accuracy is meanless. For LED driver, we mainly care about the current accuracy and match.
Table2 has list the result when each error occurs, I think it's very clear to understand. Latch off means it will stop working, retry means it will retry to work again. And there is detail description on the datasheet. I suggests you to read carefully.
Regards
Sean

Thank you for your answer!

We have a new question about short and open protection.
Please tell us the operation about TPS61196.

Example 1.
One channel : operating open or short protection
Other channel : Lighting LED as usual

Example 2.
One channel : operating open or short protection
Other channel : Stop LED lighting
(All channels stop LED lighting)


which one is correct?


Best regards,


Takahiro Nishizawa

Hi Takahiro,

    Example 1 is correct. TPS61196 will remove open or short channel and other channels is not affected.

Regards

Sean

Thank you for your answer!

For example,

Ch1 : open or short protection
Ch2 : operating as usual(keep lighting LED)
Ch3 : operating as usual(keep lighting LED)
Ch4 : operating as usual(keep lighting LED)
Ch5 : operating as usual(keep lighting LED)
Ch6 : operating as usual(keep lighting LED)


Is this understanding correct?
And are the above operations listed in the datasheet?


Best regards,


Takahiro Nishizawa