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MSP430FR6820 LCD Bias internally

Hidetaka
Expert 1080 points
Other Parts Discussed in Thread: MSP430FR6820, MSP430FR4133

Hello,

My customer is going to adopt MSP430FR4820. 

I have received the inquiry from the customer. 

721 pages of "www.ti.com/.../slau367 f/slau367f.pdf"  have the next description. 

"When the internal charge pump is used, a 4.7uF or larger capacitor must be connected between theLCDCAP pin and ground. "

Here, 4.7uF is is connected LCDCAP/R33. 

However, I do not find the description about R23, R13, and R03

What should you do with each pin of R23, R13, and R03? 

Is it necessary to connect a capacitor outside? 

If it is recommendation to connect a capacitor, is the capacity good how?

Regards, Hidetaka.

  • 0
    TI__Guru 69106 points

    Hi Hidetaka-san,

    This is for the MSP430FR6820 device with the LCD_C module, correct? The 4.7uF cap is only needed for the charge pump. For R03/13/23, these pins are for setting up an external bias resistor network. So you would only connect resistors here (if you are using an external bias resistor network instead of an internal bias resistor network) - see Figure 27-4 Bias Generation and section 27.2.5.2. You are not required to put caps on these pins.

    Now, if you were using the MSP430FR4133 device, that device family has the LCD_E module and on that family there are caps required on R03/13/23. Perhaps that was why you were asking?

    You can find the information for required caps (for either device mentioned above) in the device datasheet under Specifications > Timing and Switching Characteristics > LCD Controller, and there you will see listed what caps are required. For FR68xx, the only listed one is CLCDCAP. For FR41xx, there are listed required caps for CLCDCAP, CR33, CR23, and CR13.

    You can also find more LCD guidance in this app note: http://www.ti.com/lit/pdf/slaa654 Designing with MSP430 and Segmented LCDs

    Regards,

    Katie

  • 0 in reply to Katie Pier
    Expert 1080 points
    Hello, Katie-san.

    I looked at the data sheet of MSP430FR4133, in MSP430FR4820, thought how I was and asked.

    A capacitor is required only for LCD_E.

    Thank you.

    Regards, Hidetaka.
  • 0 in reply to Hidetaka
    TI__Guru 69106 points
    Hidetaka-san,

    I'm not aware of a part called MSP430FR4820 - do you mean MSP430FR6820?
    -Katie
  • 0 in reply to Katie Pier
    Expert 1080 points
    Hello, Katie-san.
    I was mistaken in the device name.

    MSP430FR6820 is correct.

    Regards, Hidetaka.

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