POWER SUPPLY DATA
For the standard evaluation board (4x20mA series white LEDs application), in which the output
voltage is around 15V and output current is 20mA, the power supply data is provided in Fig 1. to
Fig. 4. The white LEDs used here were from LUMEX (Part Number: SML-LX2832UWC-TR).
90
85
80
75
70
65
60
55
50
2.7
3
3.3
3.6
3.9
4.2
Input Voltage (V)
Fig. 1 Efficiency vs Input Voltage
20
16
12
8
4
0
0
20
40
60
80
100
PWM Duty Cycle (%)
Fig. 2 Average Io vs SHDN duty cycle
Vsw
IL
(0.5A/DIV)
Vout
(AC)
Fig. 3 Typical Switching Waveform
(Vin=3.3V)
.
Vout
(AC)
Fig. 4 Output Ripple (Vin=2.7V)
4