TPS61196: Is it possible to use TPS61196 under the condition that LED current per one IFB pin is less than 50mA?

Hi Shinsuke,
Yes, you can use TPS61196 with less than 50mA per channel. The What's your detail application? I think TPS6196 is the suitable device for your description about your application?
Regards
Sean

Dear Mr.Zhou

I appreciate your rapid response.

The reason why I asked this question is that the datasheet says
"Each string has an independent current regulator providing a LED current
adjustable from 50 mA to 400 mA within ±1.5% matching accuracy.".
From this description I guessed that this IC can NOT be used at ILED<50mA.

Please examine what "from 50 mA to 400 mA" actually means.

Best regards,
Shinsuke Tanaka

Hi Shinsuke,
For TPS61196, we recommend to adjust the maximum current pre channel from 50mA to 400mA. Because we can confirm very good accuracy and match within this range. For your application, I suggest you to set the maximum current to 50mA per channel. Because when you set to 50mA per channel and you can refer to Figure 5 and Equation 3 to choose suitable resistors. BTW, TPS61196 is designed for large size panel. Can you tell me how many leds per string? How about use 6 channel with less leds per channel. In this way, LP8556 is more suitable for your device(but the maximum output voltage is less than 45V).
Regards
Sean

Dear Mr.Zhou,

I appreciate your rapid and detailed response.

Please let me have one question and one comment regarding your responses.

Q3.
>For TPS61196, we recommend to adjust the maximum current pre channel from 50mA to 400mA.
>Because we can confirm very good accuracy and match within this range. For your application,
>I suggest you to set the maximum current to 50mA per channel. Because when you set to 50mA per channel
>and you can refer to Figure 5 and Equation 3 to choose suitable resistors.
In the past I asked how the value of ILED on this IC should be set on this community.
And at that time, the response was that ILED of this IC should be set slightly lower
than the LED current spec shown on LCD Panel datasheet.
It seems for me that this response is correct because I now understand that
the current which flows LED string must be smaller than the maximum current value
shown on the LCD panel datasheet and otherwise LED string may be damaged.
For details, please see below;
e2e.ti.com/.../678787
So, from the above viewpoint, I guess we can NOT set ILED to 50mA on our circuit,
which controls the LCD panel whose LED current per string is 30mA-40mA.
If ILED is set to 50mA, TPS61196 tries to sink 50mA on the LED string
and 50mA, which exceeds the maximum current value shown on LCD panel datasheet,
actually flows LED strings, which will cause damages on LCD panel.
Could you please let me know if my understanding is correct?


>BTW, TPS61196 is designed for large size panel. Can you tell me how many leds per string? How about use 6 channel
>with less leds per channel. In this way, LP8556 is more suitable for your device(but the maximum output voltage is less than 45V).
The characteristics of the LCD panel we want to use are as follows;
-The LDC panel has two connectors to which 4 LED strings are connected respectively.
-LED current is 30mA-40mA per one string.
-The required anode voltage to LED strings is about 70V at maximum.
Unfortunately, it seems that LP8556 cannot be used because
the required anode voltage to LED strings is about 70V at maximum,
which is much bigger than 45V.
If there are any other IC which is suitable to the above characteristics, please let me know.

Best regards,
Shinsuke Tanaka

Dear Mr.Zhou,

I'm sorry to bother you repeatedly, but could you please respond to my question Q3 posted on Nov.28?
The points are,
-When TPS61196 is used for the LCD panel whose LED current range per one LED string is less than 50mA,
how should we set ILED value?
For example, if the LCD panel's datasheet says that LED current per one LED string is
Typ 30mA Max 40mA, what value is appropriate for ILED?
You mentioned that under such condition ILED should be set to 50mA.
But I'm afraid that if ILED is set to 50mA, TPS61196 sinks 50mA then 50mA flows on LED string
and this may damage LCD panel because 50mA is bigger than the maximum value of LED current per string
shown on the LCD panel's datasheet.

Best regards,
Shinsuke Tanaka