LT3750 Capacitor Charger Controller UFEATURESDESCRIPTIO ■ Charges Any Size Capacitor The LT®3750 is a flyback converter designed to rapidly ■ Easily Adjustable Output Voltage charge large capacitors to a user-adjustable target volt- ■ Drives High Current NMOS FETs age. A patented boundary mode control scheme* mini- ■ Primary-Side Sense—No Output Voltage Divider mizes transition losses and reduces transformer size. The Necessary transformer turns ratio and two external resistors easily ■ Wide Input Range: 3V to 24V adjust the output voltage.* A low 78mV current sense ■ Drives Gate to VCC – 2V accurately limits peak switch current and also helps to ■ Available in 10-Lead MS Package maximize efficiency. With a wide input voltage range, the U LT3750 can operate from a variety of power sources. A APPLICATIO S typical application can charge a 100µF capacitor to 300V ■ Emergency Warning Beacons in less than 300ms. ■ Professional Photoflash Systems The CHARGE pin gives full control of the LT3750 to the ■ Security/Inventory Control Systems user. The DONE pin indicates when the capacitor has ■ High Voltage Power Supply reached its programmed value and the part has stopped ■ Electric Fences charging. ■ Detonators , LTC and LT are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. *Protected by U.S. Patents, including 6518733, 6636021. UTYPICAL APPLICATIO300V, 6A Capacitor Charger T1 D1 V 1:10 V TRANS OUT 300V 56µF 6A Charge Time 10µF • ×2 + 300 100µF VTRANS = 18V • VTRANS 60.4k 250 VCC VCC RVOUT V 12V TRANS = 6V 100k 10µF 200 43k VTRANS = 12V DONE RDCM (V) LT3750 150 OUTV OFF ON CHARGE GATE M1 100 SOURCE 50 GND RBG 12mΩ 0 2.49k 100pF 0 0.1 0.2 0.3 0.4 0.5 TIME (SECONDS) 3750 TA01a 3750 TA03c 3750fa 1
