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TLC5952: Is the TLC5952 suitable for my Appication

Neil Kurzman13
Prodigy 100 points
Part Number: TLC5952
Other Parts Discussed in Thread: TLC59281

I have an application where I want to use a 3 digit seven segment display.

Each segment will be driven at 10-15 milliamps, with Vcc = 5VDC.

The TLC5952 looks suitable. Is this an acceptable choice for this?  Is there a better choice?

Does this Chip likely have a 10 year remaining Buy Life?]

  • 0
    TI__Genius 13700 points
    Hello Neil,

    In general TI has a policy that avoids obsolescence if the part is still well received and actively being purchased. That said we do not plan out a obsoleting analog parts on a time horizon of 10 years.

    That said the TLC5952 is a possible part that should work fine.

    The other option is to use BCD to discrete segment LED drivers like those in the filtered search below:
    www.ti.com/.../led-driver-products.page Segment
  • 0 in reply to Ryan May
    Prodigy 100 points

    That is Good to know on the obsolescence 

    The TLC5952 turns out not to be a great choice since the Blue channel has a different current setting than the Red and Green ones.  I was hoping to use each color for a Digit.

    I found the TLC59281 that has good channel to channel and device to device matching so I should be OK with  3 digit 7 segment displays.  

    It also appears to have a common footprint, and is cheap

    Agree?

    Is there a rule of thumb for what percent is OK for segment to segment and digit to digit matching on a 7 segment display?

    Note: you link is poor for searching Signage/Linear chips. The Power management Guide is better, but can't be filtered since it is a PDF.

    The BCD stuff would require a lot of series resistors.

  • 0 in reply to Neil Kurzman13
    TI__Genius 13700 points
    Hello Neil,

    Here is a link to more information on TI's Obsolescence Policy:
    www.ti.com/.../product_change_notification.page


    Regarding the current limits on the TPS5952. Yes, the value for Iref sets the current limit differently for the Red/Green channels versus the Blue Channels. The way that you can work around this is that you set you current limit based on the Blue channel. Then you can drive the blue channel values across their entire range. Then when driving the Red/Green channels you simply scale the value slightly. Looking at figure 10 and 11 particularly at the current limits that result from using a 2400 ohm Iref. Blue has a limit of 15mA and Red/Green have a limit of 20mA. Using this information if you set the blue channels to full scale on the current you would set the Red/Green channels to 75% of full scale which should give you a pretty close match. ou would set this using the Global Brightness Control setting (BC)

    Let me know what you think about using the Global Brightness Control register to match the current for all three banks of 8 channels.

    I do not know of any rule of thumb for matching brightness across segments and digits. I would guess something less than +-5% would a good place to start.

    I apologize about the link. I have noticed sometimes I am able to copy and share a filtered parametric search on the forums and other times I am not. It seems that this time around it is not working very well.