STEVAL-ILL013V1 Datasheet, PDF (5/43 Pages) STMicroelectronics – 80 W offline LED driver with PFC

Getting started
2
Getting started
UM0670
Note:
This section is intended to help designers begin evaluating the board quickly, describing
how the board should be connected with the load and how the jumpers adjust the output
LED current.
As mentioned in the introduction, the board has a nominal output power of 80 W and the
output LED current can be set to 350 mA, 700 mA or 1 A. The LEDs are connected to one
string. Basically, this means if the LED current is set to 350 mA, then the LED voltage should
be approximately 228 V in order to provide output power of 80 W. If the LED current is set to
700 mA, then the LED voltage should be around 114 V. Finally, if the LED current is set
to 1 A, then the LED voltage should be about 80 V. Assuming that a high brightness LED
has (typically) a 3.5 V forward voltage drop, the number of LEDs for the 350 mA output
current is 65, for the 700 mA output current it is 32 and for the output current of 1 A it is 23
(see Table 1). Of course, designers must recalculate the number of LEDs in cases where
the LED has a forward voltage drop other than 3.5 V. If the output LED voltage is different
than that given in Table 1, output LED current precision will be influenced so is
recommended that the total forward voltage drop across all the LEDs is as close as possible
to the calculated output voltages shown in Table 1.
Connect the LED string to the board using connector J2 or J3, being careful to observe the
correct LED polarity (anode + and cathode –). Set the output LED current to 350 mA, 700
mA or 1 A, based on how many LEDs are connected to the output. The output LED current
is set using jumpers JP1, JP2, JP3 and JP4, in accordance with the connection settings
specified in Table 2. It is not necessary to connect a dimming module with a PWM signal,
because if the module is not used the LED brightness is set to maximum level (100%
brightness). Finally, connect an input voltage to the demonstration board between 88 VAC
and 265 VAC, and the LEDs begin illuminating.
The LEDs cannot be connected during operation, when the input voltage is connected to the
demonstration board. This is because in this case the output capacitor C208 = 0.47 µF is
charged to 400 V and can cause uncontrolled peak LED current.
Table 1. LED values for different output currents
Output LED current [mA]
Output LED voltage [V]
350
228
700
114
1000
80
Number of LEDs for forward
voltage drop 3.5 V
65
32
23
Table 2. Output LED current adjustment on the demonstration board
Jumper
350 mA
700 mA
1000 mA
JP1
Not connected
Connected
Not connected
JP2
Not connected
Connected
Not connected
JP3
Not connected
Not connected
Connected
JP4
Not connected
Not connected
Connected
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Doc ID 15327 Rev 2