APPLICATION NOTE AN26

© 2005 by NIDEC COPAL ELECTRONICS CORP.

Characteristics subject to change without notice

1

Document No. 6043, Rev. A

W-6137EVAL1 EVALUATION BOARD FOR W-6137

WHITE LED DRIVER

Denisa Stefan, Applications Engineer

INTRODUCTION

This document describes the W-6137EVAL1 Evaluation Board for the COPAL ELECTRONICS W-6137 white LED

driver. The functionality and major parameters of the W-6137 can be evaluated with the W-6137EVAL1 board.

The W-6137 is a CMOS constant-current DC/DC converter that has been designed to drive with high efficiency white or

other high brightness LEDs. The device drives up to 5 white LEDs in series. A single external resistor sets the LED current

between 5mA and 40 mA. LED current can be adjusted using either a pulse width modulated (PWM) signal or a DC

voltage. Detailed descriptions and electrical characteristics are in the W-6137 data sheet.

W-6137EVAL1 BOARD HARDWARE

The evaluation board contains a W-6137 DC-DC boost converter and an array of white LEDs. As configured, the board

circuit is set to drive up to 5 white LEDs in series. The user can chose to connect the W-6137 output to the on board

LEDs string or to an external LEDs string from an application. The boards are populated with 3 white LEDs in series

connected to the W-6137 output by J3 jumper shunt connector.

The board layout provides also the option to connect a different number of LEDs, 2, 4 or 5, using a jumper shunt for one of

the J2, J4 or J5 connectors. The board schematic is shown in Figure 1.

Figure 1. W-6137EVAL1 Board Schematic

The board is powered from an external voltage applied to the VIN (T1) pad or optional from an attached 3V battery (2 x

1.5V AA). The circuit is delivered with the jumper shunt on the J3 connector, which connects the 3 LEDs string available

on board to the W-6137 output.

W-6137