CAT37TDI-T3 ON Semiconductor

CAT37 CMOS White LED Driver Boost Converter Description The CAT37 is a DC/DC step up converter that delivers a regulated output current. Operation at a constant switching frequency of CAT37 Typical Application Circuit L1 D1 6.8 H VIN 3 V to 5 V C2 C1 1 F 1 F 1 5 VIN SW C1: Taiyo Yuden JMK212BJ475 CAT37 15 mA C2: Taiyo Yuden EMK212BJ105 4 3 ON SHDN FB OFF L1: Panasonic ELJEA6R8 or equivalent GND R 1 2 6.34 Figure 1. Driver for Four HighBrightness White LEDs Table 1. PIN DESCRIPTION Pin Number Name Function 1 SW Switch pin. This is the drain of the internal power switch. For minimum EMI, minimize the trace area connected to this pin. 2 GND Ground pin. Connect pin 2 to ground. 3 FB LED (cathode) connection pin. 4 SHDN Shutdown pin. 5 VIN Input supply pin. This pin should be bypassed with a capacitor to ground. A 1 F capacitor mounted close to the pin is recommended. Table 2. ABSOLUTE MAXIMUM RATINGS Parameter Rating Unit V , FB, SHDN voltage 8 V IN SW voltage 20 V Storage Temperature Range 65 to +160 C Junction Temperature 125 C Lead Soldering Temperature (10 secs) 300 C ESD Rating Human Body Model 2000 V Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect device reliability. Table 3. RECOMMENDED OPERATING CONDITIONS Parameter Range Unit V 2.5 to 7 V IN Ambient Temperature Range 40 to +85 C Inductor L1 6.8 20% typical H Input Capacitor C1 1.0 20% typical F Output Capacitor C2 1.0 20% typical F I with 1 to 4 LEDs in series 0 to 20 mA LED NOTE: Typical application circuit with external components is shown above.