2
USING THE EVALUATION BOARD
1) Powering Up the SP6137LED Circuit
The SP6137LED Evaluation Board can be powered from a 12V power supply or from 8 alkaline
cells. Connect with short leads directly to the “VIN” and “GND” posts. Plug the 1W/3W/5W
Luxeon LumiLED between the “VOUT” and “VFB” posts. Refer to section 2 for Jumper (J1)
setup for different LumiLED applications.
2) Using the J1 Jumper for different LumiLED Applications
The SP6137LED Evaluation Board can be used to drive 1W, 3W or 5W LumiLED respectively,
this can be done by using the J1 Jumper. When no hat was used for the J1, it is setup for 1W
application. When the hat is put on 1 & 2 position, it is used for 5W application. When the hat is
put on 2 & 3 position, it is used for 3W application.
3) Selecting the Bias Resistor
The feedback voltage was programmed to be 200mV by using two divider resistors (R
2
and R
4
)
at the soft start pin. (The internal 0.8V reference was overwritten by the programmed 0.2V to
reduce the sense voltage and increase the efficiency). The bias resistor is used to set the
operating current of the LumiLED as equation
F
FB
b
I
V
R =
where V
FB
is set as 200mV, I
F
is the operating current of the LumiLED.
For 1W application, I
F
=350mA, R
b
=R
1
=0.56Ohm
For 5W application, I
F
=700mA, R
b
=R
1
//R
5
=0.28Ohm
For 3W application, I
F
=1000mA, R
b
=R
1
//R
3
=0.2Ohm
POWER SUPPLY DATA
For the standard evaluation board, the following chart shows the efficiency data for different
applications.
78
80
82
84
86
88
90
92
94
96
98
100
Single Two Three
Efficiency (%)
1W
3W
5W
Fig. 1 Efficiency data of the SP6137LED evaluation board
