SLVAFP4 October   2023 TLC59283

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction of Time-Multiplexing With TLC59283
  5. 2TLC59283 Ringing Simulation Assessment
    1. 2.1 Small Parasitic Inductance of Vin and GND On-Board Without C_sink
      1. 2.1.1 Only Add L_LED1
      2. 2.1.2 Only Add L_LED2
    2. 2.2 Parasitic Inductance of Vin and GND On-Board With 4.7nF C_sink
      1. 2.2.1 L_LED1 Reach 3uH
      2. 2.2.2 L_LED2 Reach 3uH
    3. 2.3 Parasitic Inductance of Vin and GND on Customer’s Board Without C_sink
      1. 2.3.1 Only Add L_LED1
      2. 2.3.2 Only Add L_LED2
      3. 2.3.3 Add L_LED1 and L_LED2
    4. 2.4 Parasitic Inductance of Vin and GND on Customer’s Board With 4.7nF C_sink
  6. 3TLC59283 Ringing Bench Assessment
    1. 3.1 Bench Test Without R_sink and C_sink
    2. 3.2 Bench Test With 1nF C_sink
    3. 3.3 Bench Test With 10nF C_sink
    4. 3.4 Bench Test With 150 Ω R_sink
      1. 3.4.1 Bench Test With 10nF C_sink and 150 Ω R_sink
  7. 4Calculation of Resistor Value in RC Circuit
  8. 5Summary
  9. 6References

4 Calculation of Resistor Value in RC Circuit

Usually, the value of the series resistor is determined by the setting current. The voltage dropped on the output pin needs to satisfy the requirement minimum headroom voltage.

We assume the minimum headroom voltage of output is 0.5 V. Therefore, the calculation needs to

Equation 1. V o = V L E D   -   V d   -   V f   -   I s e t * R   >   0.5 V
V o The output voltage
V L E D The voltage of VLED
V d The voltage dropped on the BJT
V f The forward voltage of LED
I s e t The setting current
R The value of series resistor