AL5802EV1
Issue 1 – October 2011
www.diodes.com
© Diodes Incorporated
3
Parts List
Designator
Description
Package
Part Number
Manufacturer
U1
Linear mode constant sink LED driver
SOT23-6
AL5802
Diodes Inc.
R1
Resistor, 6K49 +/- 1% 250ppm 250mW
1206
-
Generic
R2
Resistor, 13R +/- 1% 250ppm 125mW
0805
-
Generic
R3
Resistor, 33R +/- 1% 250ppm 125mW
0805
-
Generic
Table 1. Parts list
Performance
Figure 3 shows the performance of the AL5802 when used to regulate LED current. With
jumper 1 fitted, a load of 5 series connected low current LEDs and a supply voltage of
20VDC, the LED current is measured around 100mA at 25°C PCB temperature. Over the
typical lighting board temperature range, the LED current changes from 106mA at 0°C PCB
temperature to 85mA at 85°C.
Figure 3. LED current vs. PCB board temperature
PWM dimming can be achieved by driving the on-board ENABLE input. An external open-
collector NPN transistor or open-drain N-channel MOSFET can be used to drive the EN pin.
The PWM frequency can be around 100Hz to 1KHz. Figures 4 to 6 show the LED current
variation as the duty cycle of a 400Hz PWM dimming signal changes.
