Capacitor Charger uses current-limited flyback topology.
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Press Release Summary:
Stand-alone Model LT3468, intended for digital and film cameras, can charge 100 µF capacitor to 320 V in 4.6 sec from 3.6 V battery. With controlled peak current of 1.4 A, charger, in conjunction with flyback transformer, can charge any size photoflash capacitor with efficiencies greater than 80%. Model LT3468-1 is identical to LT3468, except that current limit is 0.7 A. Both utilize primary side output voltage detection internal to device and come in ThinSOT(TM) package.
Original Press Release:
High Efficiency Photoflash Capacitor Charger in ThinSOT
MILPITAS, CA - November 12, 2003 - Linear Technology announces the LT3468, a high efficiency, fast photoflash capacitor charger. The LT3468 is a standalone solution, for photoflash capacitor charging, requiring minimum board area and no software development.
The LT3468 charges high voltage (typically 320V) photoflash capacitors quickly and efficiently. Intended for use in both digital and film cameras, the device uses a current-limited flyback topology. It can charge a 100uF capacitor to 320V in 4.6 seconds from a 3.6V battery. With a controlled peak current of 1.4A, the LT3468 in conjunction with a standard flyback transformer, can charge any size photoflash capacitor with efficiencies greater than 80%. A unique switching control circuit has low loss through the entire charge cycle and eliminates the high inrush current typically found in flash modules.
The LT3468-1 is identical to the LT3468 except that current limit has been reduced to 0.7A from 1.4A. This reduced input current is needed for smaller batteries in applications such as cellular phone cameras.
Both the LT3468 and LT3468-1 utilize primary side output voltage detection internal to the device. This eliminates the need for a resistor divider or discrete zener diodes and their power losses. Both are packaged in ThinSOT(TM) packages to ensure the minimal footprint/profile required in space constrained camera applications.
The LT3468 and LT3468-1 are available from stock and are priced at $1.95 each in 1,000-piece quantities.
Summary of Features: LT3468 & LT3468-1
Charges 100 µ F Capacitor to 320V in 4.6 seconds (LT3468)
Charges 50 µ F Capacitor to 320V in 5.5 seconds (LT3468-1)
VIN: 2.5V to 16V
Charges Any Size Photoflash Capacitor
Controlled Peak Current: 1.4A (LT3468), 0.7A (LT3468-1)
Uses Tiny (5.8 X 5.8 X 3mm) Transformers
Efficient Flyback Operation (>80%)
No Voltage Divider Required
ThinSOT Package
Company Background
Linear Technology Corporation was founded in 1981 as a manufacturer of high performance linear integrated circuits. Linear Technology products include operational, instrumentation and audio amplifiers; voltage regulators,power management devices, DC-DC converters and voltage references; comparators; monolithic filters; communications interface circuits; one-chip data acquisition sub-systems; pulse-width modulators and sample-and-hold devices; and high frequencydevices. Applications for Linear Technology's high performance circuits include wireless and broadband telecommunications infrastructure, cellular telephones, networking products and satellite systems, notebook and desk top computers, computer peripherals, video/multimedia, industrial and medical instrumentation, automotive electronics, factory automation, process control, military and space systems, and high-end consumer products including digital cameras, MP3 players and other electronic products.
READER SERVICE: Call toll-free 1-800-4-LINEAR (for literature only), or go to the company's web site: www.linear.com
Note: LT, AND LTC are registered trademarks of Linear Technology Corp.
