Emergency Laptop Charger means a true-portable circuit to charge Laptop computer from a commonly available power supply source.Described here is a simple circuit to charge laptop computer from any 12V car battery.This circuit can be connected to the cigar-lighter socket of the car to produce clean and stable DC supply of near 19V/5A,from the 12V battery supply.Enough and more for many laptops!
The circuit,from Elektor Electronics (UK), is built around the ubiquitous IC UC 3843 (IC1),from Fairchild (http://www.fairchildsemi.com/). The UC3843 is a fixed frequency current-mode PWM controller,specially designed for Off-Line and DC to DC converter applications with minimum external components. This IC features a trimmed oscillator for precise duty cycle control, a temperature compensated reference, high gain error amplifier, current sensing comparator and a high current totempole output for driving a Power MOSFET.
Features of UC3843
• Low Start up Current
• Maximum Duty Clamp
• UVLO With Hysteresis
• Operating Frequency up to 500KHz
In this circuit IRL2505 (T1) power mosfet is used as the inductor driver.IRL 2505,the Fifth Generation HEXFET from International Rectifier (http://www.irf.com/) utilize advanced processing techniques to achieve extremely low on-resistance per silicon area.
Features of IRL2505
- Advanced Process Technology
- Ultra Low On-Resistance
- Dynamic dv/dt Rating
- 175°C Operating Temperature
- Fast Switching
- Fully Avalanche Rated
- Logic-Level Gate Drive
Another major component is the 56uH power inductor.A preset-pot (P1) is added here to "fine tune" the output volatge level.After construction on a suitable piece of veroboard,enclose the whole circuit in an attractive and convenient plastic/metal box of your choice.
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