Application Note 32

Doc. No. 6050 Rev. A

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The board is powered from an external voltage

with no LEDs soldered on board. The user can solder

his white LEDs on the W-6238 board (8 to 10 LED

string pads layout provided) or he can choose to

(T7) and LED (T10) test points.

The LED current is set through the external resistors

connected to the FB pin (R1, R2). Using the variable

resistor R2, the LED current can be set from 3mA to

40mA. Most white LEDs are driven at a maximum

current between 15mA and 20mA to ensure a pure

“white” light.

The board also demonstrates the W-6238 shutdown

mode and LED brightness control by using an external

PWM signal or a DC voltage. Resistors R3 and R5

(R5 – soldered on board by the user) are used to

adjust the LED current using the dimming control with

an external applied DC voltage on the FB pin. The

ON/OFF operation and dimming control can be

selected

using

the

jumper

options

for

the

J1

connector.

Test points T1 to T10 are available to apply the

external voltages/signal generator or to measure the

output voltages / signals provided by W-6238.

The component placement is shown in Figure 2.

Table 1 presents the component list for this evaluation

board.

Figure 2. W-6238EVAL1 Board

W-6238 White LED Driver

W-6238EVAL1

Rev.1.0

W-6238

COPAL ELECTRONICS

www.nidec-copal-electronics.com +81-3-3364-7055