CAT4237BGEVB

CAT4237EVAL2EVB CAT4237 High Voltage White LED Driver Evaluation Board User's Manual http://onsemi.com EVAL BOARD USER’S MANUAL Introduction string available on board or to an external LEDs string from an application. The board provides also the option to connect a different number of LEDs available on board, 6, 7 or 8, using a jumper shunt for one of the J2 to J4 connectors. The board schematic is shown in Figure 1. The board is powered from an external voltage applied to the VIN (T1) pad. The circuit is delivered with the jumper shunt on the J4 connector, which connects the 8 LEDs string available on board to the CAT4237 output. The user can move the jumper to other connector, J2 or J3, if they desire to connect a different number of LEDs (6 or 7 LEDs). The user can connect their own white LEDs between VOUT (T7) and LED (T10) test points, with no jumper shunt set to any of J2 to J4 connectors. 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 3 mA to 30 mA. Most white LEDs are driven at a nominal current between 15 mA and 20 mA to ensure a pure “white” light. This document describes the CAT4237EVAL2 Evaluation Board for the Catalyst Semiconductor CAT4237 white LED driver. The functionality and major parameters of the CAT4237 can be evaluated with the CAT4237EVAL2 board. The CAT4237 is a high voltage CMOS constant−current DC/DC converter that has been designed to drive with high efficiency white or other high brightness LEDs. The high−voltage output stage allows driving up to 8 white LEDs in series. A single external resistor sets the LED current between 5 mA and 30 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 CAT4237 data sheet. CAT4237EVAL2 Board Hardware The evaluation board contains a CAT4237 DC−DC boost converter and an array of white LEDs. As configured, the board circuit is set to drive up to 8 white LEDs in series. The user can chose to connect the CAT4237 output to the LEDs VIN GND GEN/DC GND FB SGND LQ1 T1 T2 T3 J1 GND R4 200 kW T4 T5 GND R5 10 kW T9 33 mH C1 4.7 mF GND 1 SW GND 5 1 VIN SW CAT4237 SHDN 3 4 FB GND 2 U1 C2 0.22 mF GND L1 LED T10 GND GND L2 L3 R3 1 kW R2 100 W L4 L5 R1 6.81 W GND T8 VOUT T7 D1 T6 GND GND J2 J3 J4 L6 L7 L8 Figure 1. CAT4237EVAL2 Board Schematic © Semiconductor Components Industries, LLC, 2011 August, 2011 − Rev. 5 1 Publication Order Number: EVBUM2017/D CAT4237EVAL2EVB Test points T1 to T10 are available to apply the external voltages/signal generator or to measure the output voltages/signals provided by CAT4237. The component placement and the board picture are shown in Figure 2. Table 1 presents the component list for this evaluation board. The board also demonstrates the CAT4237 shutdown mode and LED brightness control by using an external PWM signal or 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. Figure 2. CAT4237EVAL2 Board Table 1. CAT4237EVAL2 EVAL BOARD LIST OF COMPONENTS Name Manufacturer U1 Catalyst C1 Taiyo Yuden (or Panasonic) C2 Taiyo Yuden (or Kemet) L1 D1 Description Part Number Units CMOS White LED Driver, TSOT23 − 5−pin CAT4237TSI 1 Ceramic Capacitor 4.7 mF/6.3 V, X5R, Size 0805 JMK212BJ475 (or Digi−Key PCC2315CT−ND) 1 Ceramic Capacitor 0.22 mF/50 V, X5R(X7R) (C1206C224K5RACTU) 1 Sumida (or TDK) Inductor 33 mH, Low DCR, High Current CDRH3D16−330 or VLCF4018T−330MR42−2 1 Central Schottky Diode, Low VF, High Current, SOD−323 CMDSH05−4 1 R1 Yageo SMT Resistor 1/16 W, 6.81 W, 0603 Digi−Key 311−6.81HCT−ND 1 R2 Bourns Trimmer Pot, 1/4”, 100 W 3329W−101−ND (or equiv) 1 R3 Yageo SMT Resistor 1/16 W, 1.0 kW, 0603 Digi−Key 311−1.0KHCT−ND 1 R4 Yageo SMT Resistor 1/16 W, 200 W, 0603 Digi−Key 311−200KHCT−ND 1 R5 Yageo Metal Film Resistor 1/16 W, 10 kW (Not Soldered on Board) Digi−Key 10.0KXBK−ND 1 L1 to L8 Nichia White LED, SMT NSCW100 or NSCW335 8 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 Pin Receptacle (Test Points) #0149−0−15−01−30−14−04−0 (or equiv) 10 T1 to T10 http://onsemi.com 2 CAT4237EVAL2EVB CAT4237 EVALUATION The CAT4237EVAL2 gives the user a way to evaluate the CAT4237 in a typical application of driving multiple LEDs. The user can connect 6 to 8 LEDs in series to the CAT4237 output, using the jumper options for J2, J3 or J4 header−pin connectors. The following steps are an example of how the user can evaluate the CAT4237 white LED driver: Driving 8 LEDs in Series and Shutdown Mode 1. Connect the 8−LEDs string to the CAT4237 output using a jumper shunt on J4 header−pin connector (J2 , J3 not jumpered) 2. Set the R2 potentiometer to the middle position 3. Apply the external voltage supply, VEXT (3.0 V < VIN < 5 V) between VIN (T1) and GND (T2) 4. The CAT4237 is in the shutdown mode (SHDN pin is connected to GND) if the J1 connector is not jumpered • Connect a current meter between VEXT and VIN pad to measure the shutdown current: ISD