LOW POWER BLOCKING DIODE FOR BATTERY CHARGERS
Original Publication Date: 1998-Jun-01
Included in the Prior Art Database: 2002-Jul-09
In charging devices for secondary batteries, there is generally a need for a means to prevent the battery from supplying power to the charger and to keep the heat dissipated by the circuit elements to a minimum. The first issue is typically accomplished by placing a diode (Dl) between the power source (Vs) and the battery to allow current to flow in only one direction, i.e. from the power source to the battery (Figure I). The latter issue is typically addressed with some combination of natural convection elements and/or forced convection elements. Because the blocking diode must also dissipate the power from the charger (this can be :as high as 3 watts or more) careful attention to thermal issues is required, typically necessitating a heat sink on the diode. However, in some applications the size and appropriateness of heat sinks, fans, etc. are either severely restricted or completely undesirable. Moreover, simply paralleling 2 or more diodes together is often neither an attractive nor reasonable alternative.