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Article: Two cores marry, make swinging choke.(Design Ideas Annual Supplement 1995)
- Article from:
- EDN
- Article date:
- February 15, 1996
- Author:
CopyrightCOPYRIGHT 1996 Reed Business Information, Inc. (US). This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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Designing an output choke for a switch-mode power supply that must operate over large load variations can be problematic. If you design the inductor for the maximum load the power converter will see, the inductance will be below the critical inductance required at light load. This inadequate inductance will cause the voltage on the output capacitor to peak up, resulting in increased ripple on the output.
If, on the other hand, you design for the much larger value of inductance required at light load, your inductor will be overspecified for the nominal load and will be too large physically.
One solution is to add a bleeder resistor on the output of the ...