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TLC5928: 24V plus with TLC5928 - can bigger LED strings be driven?

Part Number: TLC5928

Hi,

I want to use the 5928 for 7 segment drive in some large LED numbers - These have 10 series LEDs in and need 24V minimum as an Anode voltage. The data sheet ( indeed nearly all data sheets for these type parts) have a lower max value. - Is there a reason or can I implement a Zener or emitter follower type circuit with each chain to limit the (leakage) voltage at these pins as the normal voltage drop across the LEDs would bring the voltage to a lower value - I do not understand this max value? what am I missing? - Thank you. 

  • Hi, Dave,

         If the anode voltage exceeds the max value mentioned in the datasheet, the voltage on out_x pin will rise to a value close to anode voltage over a sufficient long time. The device has a risk to be broken on this occasion. Hence, it is not recommended to use anode voltage exceeding the max value. However, it's ok that you use 17V(or lower voltage) Zener to clamp the voltage of out_x pin, which will be helpful for protecting the device from breaking down by the high voltage.

  • Hi Charles,

    Thank you so much! I did expect this but appreciate you answering the question and for your comments. Fully understand.

    Capacitance across the LEDs has alway been an issue as well so I will put a shunt resistor (5-10K) across the LED string to a 15V zener - this I am sure will improve transient ( as I have with my own discrete designs) and be within the limits of the device.

    Many thanks for this.