CAT4238AEVB CAT4238 10-LED Boost Converter Evaluation Board User s Manual CAT4238AEVB The board is powered from an external voltage applied to PWM signal or a DC voltage. Resistors R3 and R5 the V (T1) pad. The circuit is delivered with no LEDs (R5 soldered on board by the user) are used to adjust the IN soldered on board. The user can solder his white LEDs on the LED current using the dimming control with an external CAT4138 board (8 to 10 LED string pads layout provided) applied DC voltage on the FB pin. The ON/OFF operation or he can choose to connect the LEDs from his application and dimming control can be selected using the jumper between V (T7) and LED (T10) test points. options for the J1 connector. OUT The LED current is set through the external resistors Test points T1 to T10 are available to apply the external connected to the FB pin (R1, R2). Using the variable resistor voltages/signal generator or to measure the output R2, the LED current can be set from 3 mA to 40 mA. Most voltages/signals provided by CAT4238. white LEDs are driven at a maximum current between The component placement is shown in Figure 2. Table 1 15 mA and 20 mA to ensure a pure white light. presents the component list for this evaluation board. The board also demonstrates the CAT4238 shutdown mode and LED brightness control by using an external Figure 2. CAT4238AEVB Board Table 1. CAT4238AGEVB BOARD LIST OF COMPONENTS Name Manufacturer Description Part Number Units U1 ON Semiconductor CMOS White LED Driver, TSOT23 - 5pin CAT4238TD-G 1 C1 Taiyo Yuden Ceramic Capacitor 4.7 F/6.3 V, X5R, Size 0805 JMK212BJ475 1 (or Digi-Key PCC2315CT-ND) (or Panasonic) C2 Taiyo Yuden Ceramic Capacitor 0.22 F/50 V, X5R(X7R) UMK212BJ224KG 1 (or Kemet) (Digi-Key 587-1287-1-ND) L1 Sumida Inductor 47 H, Low DCR, High Current CDC5D23B-470 1 (or CDR6D23MN-470) D1 Central Semi Schottky Diode, Low VF, 40 V, 500 mA, SOD-323 CMDSH05-4 1 R1 Yageo SMT Resistor 1/16 W, 6.81 , 0603 Digi-Key 311-6.81HCT-ND 1 R2 Bourns Trimmer Pot, 1/4, 100 3329W-101-ND (or equiv) 1 R3 Yageo Digi-Key 311-1.0KHCT-ND 1 SMT Resistor 1/16 W, 1.0 k , 0603 R4 Yageo SMT Resistor 1/16 W, 200 k , 0603 Digi-Key 311-200KHCT-ND 1 R5 Yageo Metal Film Resistor 1/16W, 10k Digi-Key 10.0KXBK-ND (Not Soldered on Board) L1 to L10 Nichia White LED, SMT (Optional) NSCW100 or NSCW335 10 J1 6-pin Header Connector, 0.1, Single Strip Digi Key S1012-06-ND (or equiv) 1 J2 to J4 2-pin Header Connector, 0.1, Single Strip Digi Key S1012-02-ND (or equiv) 3 (optional) T1 to T10 Mil-Max Pin Receptacle (Test Points) 0149-0-15-01-30-14-04-0 (or equiv) 10