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ISO7820LL: isolation between graphic processor and TFT LCD

seo hyeoksu
Prodigy 120 points
Part Number: ISO7820LL
Other Parts Discussed in Thread: ISO1640, ISO7730, ISO7760

Hello, 

design it to insulate between the graphic processor and TFT LCD as follows.

There are various Isolation ICs in the power, but I cannot find Isolation ICs for Rgb666.

1. Is there a isolation IC for RGB666?

2. If I don't have an isolation IC, should I convert RGB to LVDS in RGB -> LVDS -> LVDS Isolation IC -> RGB order and isolate?

Best regards

  • 0
    TI__Mastermind 25060 points

    Hello Seo, 

    Thank you for reaching out. I am assuming the RGB signals you mention are CMOS, logic-level signals, based on your description. If the RGB signals are logic level signals, then you could use either a digital isolator (ISO7730) or an I2C isolator (ISO1640) to isolate these signals. The I2C isolator would be recommended if the signals are going to an external PCB over a short distance of wire.

    You would not need to use a differential protocol for these signals (like LVDS) unless the signal needed to travel longer cable lengths. 

    Best,
    Andrew 

  • 0 in reply to Andrew J
    Prodigy 120 points

    Hello, The product requires 18 bit data lines(R[5:0], G[5:0], and B[5:0]), CLK, H sync, V sync, and DE pin (22 channels in total)

    Will 22 signals be properly recognized if they are isolated through 8 ICs?

  • 0 in reply to seo hyeoksu
    TI__Mastermind 25060 points

    Hello Seo, 

    There will be no issues in transmitting signals across 8 IC's as long as all the devices are powered. Please note that data sheet specifications are characterized across process, voltage and temperature (unless otherwise noted in the table). This means the datasheet specs account for part-to-part variation. 

    In general, it is up to the MCU to handle the protocol and timing of the communication. 

    Best,
    Andrew

  • 0 in reply to Andrew J
    Prodigy 120 points

    Hello Andrew

    According to my understanding, does it mean that it will be designed by changing it as shown in the picture below?

  • +1 in reply to seo hyeoksu
    TI__Mastermind 25060 points

    Yes, your understanding is correct. You can also use a higher channel count isolator to save some board space, like ISO7760. 

    Best,
    Andrew

  • 0 in reply to Andrew J
    Prodigy 120 points

    Thank you Andrew