EUP2539
Light Load Switching Waveform
Typical Operating Characteristics (continued)
Open LED Supply Current vs. VIN
6LED,VIN=5.5V,ILED<1mA,L=47µH
5
SW
4
3
2
1
0
10V/div
Inductor
Current
50mA/div
VOUT
AC Coupled
20mV/div
500ns/div
3
3.5
4
4.5
5
5.5
Input Voltage (V)
Power-up With 10 LEDs at 20mA
Typical Switching Waveforms
SW
VEN
20V/div
2V/div
Inductor
Current
VOUT
20V/div
50mA/div
Input
Current
VOUT
AC Coupled
50mV/div
100mA/div
100µs/div
1.00µs/div
Enable to Open LED Waveforms
Enable to Open LED Waveforms
VEN
VEN
2V/div
2V/div
VOUT
VOUT
20V/div
20V/div
SW
SW
20V/div
20V/div
25.0ms/div
50.0µs/div
DS2539 Ver1.1 Apr. 2009
7