TLC6C5748-Q1: current setting for one of the ICs

Hi 

I am looking into this

BR, Gracie

Hi Cherry

Why are there 2 same threads? 

https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1239875/tlc6c5748-q1-tlc6c5748-q1

Are you raising for 1 problem? If so, I will only ask one.

BR, Gracie

Hi Gracie,

I believe this one is raised by the customer and we could close the thread here. Thank you for the support.

Thanks and regards,

Cherry

Hi Cherry,

This slides could answer all your questions.

TLC6C5748-Q1 program procedure.pptx

2. It can be 0 or anything. Not important. Invalid 

BR, Gracie

Hi Gracie,

Indeed this thread(https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1239875/tlc6c5748-q1-tlc6c5748-q1) is raised by the end customer but you have replied here, I will ask the customer discuss the issue with you here. Thank you.

Thanks and regards,

Cherry

Hi Cherry,

OK. Pls tell the customer to see my reply before and avoid same threads next time. Thanks.

BR, Gracie

Sorry, my colleague and I asked this question at the same time, so it seems to be a duplicate. We hope to hear from you within this week

I have already replied above.

Gracie

Hi,Gracie,

There are 4 ICs on our LED light board, so I sent four times of GS data (768bit4) and four times of common shift register (769bit4), but when I changed the current value (MC), I found the brightness of the light board no change.

Hi,Gracie,please help us as soon as possible

Hi Chao,

We have holidays off. 

You need to send control data and then GS data as attached above. And MC data for different ICs should be different. Also, it's possible you didn't latch correct data. You may check the SOUT to see if you have sent the correct control data. When MSB=1, the SOUT should be the same as SIN.

BR, Gracie

Hi,Gracie,

Sorry to bother you, but I want to know why the MC data is different for different ICs? What should I do if I want the area controlled by different ICs to have the same current?

Hi Chao,

I just mean Control data could be different for different ICs, not necessarily to be different. If you want the same value, then just send the same MC value for every IC. That's OK.

BR, Gracie

Hi,Gracie,

Do GS data and control data only need to be sent once? What is the reason why the waveforms of SIN and SOUT are different?

Hi Chao,

Control data, not GS data.

chao.xu said:

Do GS data and control data only need to be sent once?

Could you pls compare SIN control data and SOUT with logic analyzer or waveform? GS data SIN should be different from SOUT because there is SID information.

BR, Gracie

Hi,Gracie,

The control data only needs to be sent once, but does the GS data need to be sent multiple times?

Sorry we only have an oscilloscope to see their waveforms are different.

If you send GS data once and GSCLK is sending at a certain frequency, let's say 10MHz, it should be on. But usually GS data latch is sent at a certain frame rate.

BR, Gracie

Hi,Gracie,

The frequency of GSCLK I set is 10MHZ. There are 4 ICs on our light board. How many times do we need to send GS data and control data?

Hi Chao,

You may not understand the control data and GS data, The  slides are quite clear: 

Control data is initialization for LED driver including MC, DC, BC, FC;

GS data is brightness data from  video and passed from TCON. This data update rate is called frame rate. Usually 60Hz.

Hi,Gracie,

My understanding is that GSCLK is generated by PWM and its frequency is 60HZ, right?

No.

PWM frequency needs to be >=20KHz to avoid audible noise.

https://www.ti.com/lit/pdf/slvafi8

BR, Gracie

Hi,Gracie,

Thank you very much, I just set the PWM frequency to 60HZ, and then successfully lit the light board, it seems a little different from what you said.