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Inquiry regarding supply voltage on TLC59281

Atsushi Okui
Genius 4015 points
Other Parts Discussed in Thread: TLC59281, TLC59282

Hello, all

Now we are considering to have new design with TLC59281, then would like to know the detail of supply voltage on this device.

Please refer to the item below, and feedback us with your comment.

We have some system restrictions when using this device.

1. Power supply for LED (OUT0 to OUT15) is fixed to 5V

2. Serial communication line from MCU is fixed to 3.3V

On this situation, we assume that we need to supply 3.3V into VCC on TLC59281.

Please let us clarify whether above configuration could be acceptable for this device.

We thank you in advance for your information.

Best regards,

  • 0
    TI__Intellectual 955 points

     Hello Atsushi,

     Yes, if input signal voltage range is 0-3.3V, then the VCC voltage should be set to 3.3V.

     Best regards,

     Kazuya Nakai.

  • 0 in reply to Kazuya Nakai
    Genius 4015 points

    Nakai-san,

    Thank you for your reply on this inquiry.

    Please let me confirm whether enclosed configuration is possible for this device.

    I assume that the voltage gap between OUT0-15 and external 5V causes some power consumption, which needed to care for heat influence on system.

    Thank you once again for your confirmation. 

    Best regards, 

  • 0 in reply to Atsushi Okui
    TI__Intellectual 955 points

     Hello Atsushi-san,

     Your circuit will work correctly.

     But TLC59281 doesn't have switching time delay circuit of noise reduction because this device was designed for LED video pannel and LED video panel needs smaller Ton_err which is a parameter of switching characteristics. Total current changes from zero to 560mA (Max) or 560mA to zero with 10ns~30ns. So big noise may be generated on GND line or LED power line if the routing impedance is not small. If you don't need such high acurate Ton_err, it is better to replace TLC59281 with TLC59282. TLC59282 has switching time delay circuit for noise reduction.

     For your refference, the device power dissipation can be caluculated by the following equation.

     TLC59281 Pd (W) = VCC * ICC + VOUTn * IOUTn * N * ONduty

      where: VCC: Device VCC voltage (V), ICC: Device VCC current (A), VOUTn: TLC59281 OUTn voltage when driving LED current (VOUTn = LED anode side voltage - LED forward voltage at the current),  IOUTn: LED current which adjusted by IREF - GND resistor, N: number of OUTn drivint LED at same time, ONduty: dutu ration controlled by BLANK.

     Also the following power is dissipated on LED lamp.

    LED Pd (W) = forward voltage * forward current.

    Best regards,

    Kazuya Nakai.