TLC5954 Datasheet, PDF (36/45 Pages) Texas Instruments – TLC5954 48-Channel, Constant-Current LED Driver with Global Brightness Control, LED Open-Short Detection, and Power-Save Mode

TLC5954
SBVS241 – APRIL 2014
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10 Power Supply Recommendations
The V_CC power-supply voltage should be well regulated. An electrolytic capacitor must be used to reduce the
voltage ripple to less than 5% of the input voltage. Furthermore, the V_LED voltage should be set to the voltage
calculated by Equation 2:
V_LED ≥ LED Maximum V_F × Number of LED Lamps Connected in Series + 0.4 V (5 mA for MC Data Example)
where:
• V_F = Forward voltage
(2)
Because the total current of the constant-current output is large, some electrolytic capacitors must be used to
prevent the OUTXn pin voltage from dropping lower than the calculated voltage from Equation 2.
11 Layout
11.1 Layout Guidelines
1. The decoupling capacitor should be placed near the VCC and GND pin.
2. The GND pattern should be routed as widely as possible for large GND currents. Maximum GND current is
approximately 1.52 A.
3. The routing between the LED cathode side and the device OUTXn should be routed to be as short and
straight as possible to reduce wire inductance.
4. The PowerPAD should be connected to the GND layer because the pad is connected to GND internally. The
PowerPAD also should be connected to the heat sink layer to reduce device temperature.
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