LD7268

Photoflash Capacitor Charger LD7268 3/21/2005 REV: 01 General Description The LD7268 is an ideal charge control IC for flash units with internal soft start, adjustable charging current and output voltage. It provides a proprietary constant current charging algorithm which charges photoflash capacitor quickly and efficiently. Besides, the built-in totem pole IGBT driver can drive IGBT quickly and save board space. For phone flash applications, the input current is usually limited at 500mA or 300mA. The LD7268 could easily meet either 500mA or 300mA applications. The LD7268 is available in a space-saving MSOP-10 package and is ideal for phone flash or DSC flash unit. Features z Adjustable charging current z Adjustable output voltage z Supports auto refresh z 2.8V~5V Lithium battery voltage range z Internal soft start z Tiny transformer z Totem pole IGBT driver Applications z DSC Flash Unit z Phone Flash Unit g Patented Typical Application VOUT D1 T1 C2 47µF ZD1 300V VCC C3 1µF VDD R1 100K READY C4 R2 0.1µF 1M VCC OUT1 FB RS 5.1Ω SEC CS LD7268 ISET READY CHARGE IGBT GATE Q1: AOS / AO3402, RG OUT2 TRIGGER GND T1: LP=10/16.5µH, for input current =500/300mA ZD1:Origin /FC0300M RI =250K~450K CS=4.7~10nF Fig. 1 Phone Flash Application Q1 CHARGE TRIGGER C1 22µF VIN RI Leadtrend Technology Corporation LD7268-DS-01 March, 2005 1 LD7268 VOUT D1 T1 C2 160µF ZD1 300V Vcc C3 1µF VDD R1 100K READY C4 R2 0.1µF 1M VCC OUT1 FB RS 3.9Ω SEC CS LD72...