Scheme Keeps Current Drain Constant:  04/12/01 EDN-Design Ideas / (Schematic / circuit added 10/05)

Simple Current Source and Sink Circuits Have Low Tc:  07/04/96 EDN-Design Ideas / (Electronic Circuit diagram added 03/03)

Simple Scheme Keeps Current Drain Constant:  04/12/01 EDN-Design Ideas / (Schematic / circuit added 10/05)

Simple Variable Voltage Source:  The high current regulator below uses an additional winding or a separate transformer to supply power for the LM317 regulator so that the pass transistors can operate closer to saturation and improve efficiency. For good efficiency the voltage at the collectors of the two parallel 2N3055 pass transistors should be close to the output voltage. The LM317 requires a couple extra volts on the input side, plus the emitter/base drop of the 3055s, plus whatever is lost across the (0.1 ohm) equalizing resistors (1volt at 10 amps), so a separate transformer and rectifier/filter circuit is used that is a few volts higher than the output voltage..... (Electronic circuit added 4/05)

Step Up/Step Down Current Source Charges Batteries:  06/06/96 EDN Design Ideas  / (Schematic / circuit added 10/05)  For battery charging, the highly efficient step-down (buck) configuration is usually the topology of choice. However, a different approach is necessary if the following conditions prevail: The supply voltage is less than the battery voltage, or, even worse, the supply voltage ranges above and below the battery voltage.

Step-Up/Step-Down Converter Takes 2 to 16V Inputs:  07/16/98 EDN Design Ideas / (Schematic / circuit added 10/05) The circuit in Figure 1 is a low-cost step-up/step-down dc/dc converter. By definition, its input can range above and below the regulated voltage. The circuit includes a simple switchmode boost converter (IC1) that contains a comparator normally used to detect low battery voltage. In this case, the comparator controls an external pnp transistor that operates as a linear regulator. IC1 steps up VIN (2V minimum) to the level of VX, as determined by the jumper block, J1.....

Switching Regulator Forms Constant Current Source:  05/30/02 EDN Design Ideas  /  (added 1/05)  Many applications require current sources rather than voltage sources. When you need a high-current source, using a linear regulator is inadvisable, because of the high power dissipation in the series resistor. To solve the wasted-power problem, you can use a switch-mode regulator. The circuit of Figure 1 uses IC1, an LM2576 adjustable regulator....

TSM108 Evaluatin Board 12V to 6V DC/DC Converter:  The TSM108 is a step down controller that features constant voltage and constant current regulation.The Evaluation Board was designed to allow different converter configurations. Several options for power semiconductor footprints are available on the PCB in order to make it adaptable to a wide range of converter output power. In a first step, this application note will describe the typical application. Then the various options available on the Evaluation Board PCB will be explained.  (circuit design added 3/05)

Variable Voltage Source:  The high current regulator below uses an additional winding or a separate transformer to supply power for the LM317 regulator so that the pass transistors can operate closer to saturation and improve efficiency. For good efficiency the voltage at the collectors of the two parallel 2N3055 pass transistors should be close to the output voltage. The LM317 requires a couple extra volts on the input side, plus the emitter/base drop of the 3055s, plus whatever is lost across the (0.1 ohm) equalizing resistors (1volt at 10 amps), so a separate transformer and rectifier/filter circuit is used that is a few volts higher than the output voltage..... (Electronic circuit added 4/05)

Voltage to Current Converter Drives White LEDs:  06/27/02 EDN Design Ideas  /  (added 1/05)  You sometimes need to drive a white LED from one 1.5V battery. Unfortunately, the forward voltage of a white LED is 3 to 4V. So, you would need a dc/dc converter to drive the LED from one battery. Using the simple circuit in Figure 1, you can drive one white LED or two series-connected green LEDs, using only a few components....

Wide-Range Current-To-Frequency Converters:  National Semiconductor - Application Note   (added 2/06)