TLC6C5712-Q1: External shunt resistor to regulate the current

Shinji Tsuji

Part Number: TLC6C5712-Q1
Other Parts Discussed in Thread: TLC6C5912

Hi team,

I know this device is constant current regulator, but is it possible to use it as TLC6C5912 by using external resistor to set the LED current?

If I select the external resistor to limit the current lower than the current set by Riset of TLC6C5712, then I think the low side transistor will saturate and

the LED current will be set only by the external resistor.

Is my understanding correct?

Is there any concern if I use this device like this?

regards.

over 4 years ago

0 Frank Qiu over 4 years ago

TI__Genius 15776 points

Hi ,the resistor is used to set a max current for this device and customer could also use register to config the current with "8-Bit, 256-Step" for each channel.

You can find it in the first page of datasheet.

0 Shinji Tsuji over 4 years ago in reply to Frank Qiu

TI__Genius 14099 points

Hi Frank,

Yes I know the each channel current can be configured by the register.

What I would like to do is to control more than 12 LEDs. For example, 11 OUT(1 to 11) channels are used as constant current regulation

as specified in the datasheet, and use OUT0 to control 3 more LEDs in parallel.

I would like to control that 3 LED's current independently.

If I put external resistors on top of each 3 LEDs and limit the total current flow to OUT0 smaller than the current set by Riref,

I believe the low side FET will fully on and the total current is set only by the external resistors on top of LEDs.

I checked the behavior in my lab and it worked as I expected (OUT0 pin voltage = 0.1V).

Is there any side effect or any concern?

regards,

0 Frank Qiu over 4 years ago in reply to Shinji Tsuji

TI__Genius 15776 points

Our device is constant current source, I don't know whether it can control the current accuarcy? Because you are use resistor to divide the current.

It looks good, since it's not a typical application, so I also can't comfirm whether there is any risk in your application.

0 Shinji Tsuji over 4 years ago in reply to Frank Qiu

TI__Genius 14099 points

Hi Frank,

Yes it is not a typical application, but it is good if it can be used as such to save some cost.

regards,

0 Frank Qiu over 4 years ago in reply to Shinji Tsuji

TI__Genius 15776 points

Get it.

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TLC6C5712-Q1: External shunt resistor to regulate the current