SP7601 Evaluation Board Manual Ideal for 24V or 12V Bus Application Single Board for 0.35A, 0.7A, 1A and 1.2A Applications PWM Dimming and power cycling Small 6-Pin TSOT Package 1.2MHz Switching Frequency Enables Small Components Integrated Design with Minimal Components. Low 0.2V Reference Voltage DESCRIPTION AND BOARD SCHEMATIC The SP7601 Evaluation Board is designed to help the user evaluate the performance of the SP7601 in driving LEDs. The board can accommodate any of four different types of LEDs that should be provided by the user. Evaluation Board Schematic M1, ANPEC, APM9435K 30V, 80mOhm L1, Coiltronics LD2-390-R 39uH, 1.85A, 0.16 Ohm VIN C1, 4.7uF 50V 1 1 1 1 Supply 2 2 2 2 J1 J2 J3 J4 2 PTC PTC PTC PTC 1 Gate GND Vin LED1 LED2 LED3 LED4 RS 3k LX LUXEON K2 SEOUL EVERLIGHT LUXEON REBEL C2, 0.1uF 50V U1 TSOT-6pin 6 SP7601 D1, SMA 9V+ 3 MBRA340T3G VDR battery VFB SW1 9V- 1 2 GND 4 Rf b 60.4k 1 1 1 DIG-1 2 2 2 J5 J6 J7 5 PTC PTC PTC D2 (SOD323) 1N4148 RS1 RS2 RS3 RS4 Dimming 0.56Ohm 0.56Ohm 0.56Ohm 0.22 Ohm Rev 9/18/07 SP7601 Evaluation Board Manual Copyright 2007 EXAR Corporation USING THE EVALUATION BOARD 1) Powering Up the SP7601 LED Circuit The SP7601 LED Evaluation Board can be powered from either a 9V battery or from a power supply. To operate with a battery, plug in a 9V battery in its corresponding socket under the board. Toggle the switch SW1 to apply battery power to LED. To operate from a power supply connect leads from the supply to VIN and GND posts at the left side of the board and apply power. The board is optimized to operate from input voltage ranging from 9V to 24V. 2) Using different LEDs The SP7601 Evaluation Board has footprints for four different LEDs. Populate desired LED in the appropriate foot print and set corresponding jumper as shown in table 1. Footprint Recommended LED Jumper setting designator LED 1 LUXEON K2 J1 LED 2 EVERLIGHT ELECTRONICS J2 EHP-AX08L/DT01-P01 LED 3 SEOUL SEMICONDUCTOR J3 W42180 LED 4 LUXEON REBEL J4 Table 1- LED Jumper setting 3) Setting the LED current SP7601 has a 0.2V reference and output current can be set from Io=0.2V/Rset. Evaluation board comes equipped with Rset resistors for selecting 0.35A, 0.7A, 1A and 1.2A. Use jumper settings shown in table 2 for setting the output current to desired value. Output Jumper current(A) setting 0.35 none 0.7 J5 1 J5 and J6 1.2 J7 Table 2- Jumper setting for output current 4) PWM dimming signal For LED dimming apply a logic-level signal to the pin marked Dimming (connect the signal ground to the pin marked GND). Frequency of the dimming signal can be up to 1kHz with duty cycle ranging from 10% to 90%. As the duty cycle of dimming signal is increased, average current delivered to LED and light emitted by the LED is decreased. Rev 9/18/07 SP7601 Evaluation Board Manual Copyright 2007 EXAR Corporation 2