TLC5943: TLC5943 Vneg LED drive

Hi Venkat,

The pictures are broken. Can you post it again?

Best Regards,

Steven

Note -8V is wired to the IR LED and +8V to the VIS LED (maybe hard to tell based on resolution of picture)

Hi Venkat,

I am not sure about my understanding of your schematic. Is the below one right?  If not, please clarify.

Also, what lighting effect would you like to get?

Best Regards,

Steven

Yes you have drawn correctly. 

We will either have IR or VIS output but not both

Venkat

Hi Venkat,

Why do you put a -8V there?

Best Regards,

Steven

-8V is required because we need neg voltage to drive the IR LED (it is placed in reverese)

Hi Venkat,

Steven is out of office for business trip and will reply you before 11th Aug. Thanks.

Thanks, Hardy.

Hi Venkat,

Sorry. But I am still confused about your application.

But one thing is for sure - The below schematic is wrong, because ideally the VIS LEDs will be on all the time and the IR LEDS will be off all the time due to the presence of power rails +8V and -8V.

Steven Li said:

I am not sure about my understanding of your schematic. Is the below one right?  If not, please clarify.

Also, what lighting effect would you like to get?

I am trying to understand your application. Please let me know if my understanding is correct or not.

1. You are going to use a two-terminal component that is called BLADE TIP LIGHT. One BLADE TIP LIGHT contains three VIS LEDs, three IR LEDs and two resistors, which is connect as is shown below.
2. Sometimes you may need to apply forward current (marked green below) to the BLADE TIP LIGHT to only light up the VIS LEDs. Sometimes you may need to apply backward current (marked purple below) to the BLADE TIP LIGHT to only light up the IR LEDs. Sometimes you do not apply any current to the BLADE TIP LIGHT to let all LEDs off.
3. You need to control the current value to provide some dimming effects for both VIS LEDs and IR LEDs.
4. You have two power rails +8V and -8V, which you want to power the LEDs.
5. Sometimes you want to apply a positive voltage (<=8V) across the BLADE TIP LIGHT to generate the forward current. Sometimes you want to apply a negative voltage (|voltage| <= 8V) across the BLADE TIP LIGHT to generate the backward current.
6. You need to control seven BLADE TIP LIGHTs at the same time.

I am currently out of office for business trip. I will try my best to reply to you in my free time.

Best Regards,

Steven

This is correct

Hi Venkat,

Got it. Thanks for replying. 

A possible solution is shown below. It is quite like the "H" bridge that drives a motor. I choose to current source because in that way you can have NMOS as the low-side switch. The current paths are marked green and red.

Best Regards,

Steven