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…

http://www.powerguru.org/changing-the-output-voltage-of-a-switching-regulator-on-the-fly/ There are many different ways to change the output voltage Applications that require the output voltage of a power supply to change dynamically come from a wide…

Engineering labs are usually equipped with various power supplies, voltmeters, function generators, and oscilloscopes. One piece of equipment missing from many such labs, however, is a current source. This omission is unfortunate, because a current s…

Transistor Tutorial Summary Transistor Tutorial Summary Bipolar Junction Transistor Tutorial We can summarise this transistors tutorial section as follows: The Bipolar Junction Transistor (BJT) is a three layer device constructed form two semiconduct…

Figure 1 shows a simple, stand-alone overvoltage detector. The intent of the circuit is to monitor a voltage, VMONITOR, and set the output, VOUT, high when the monitored voltage exceeds a preset threshold. The minimum allowable threshold for this cir…

LDO Regulator High accuracy voltage regulator Vout = 2.5V * (1 + ( 5.6 / 6.8 ) ) = 4.55V Recently the author had to adapt  a standard circuit configuration  (which often uses an npn bipolar) so as to operate as a low-dropout (LDO) regulator. The circ…

The circuit in Figure 1 delivers programming voltages to an EEPROM under the control of an external DAC (not shown). You can replace the DAC with a potentiometer to create a general-purpose power supply operating from 12V and able to deliver a variab…

Cs5171: Tracking Boost Regulator Adding a current mirror circuit to a typical boost circuit allows the user to select the amount of boost voltage and ensure a constant difference between input and output voltage.   This is useful for high side drive…

Most engineers know that they can use an inexpensive, three-terminal adjustable regulator, such as Fairchild Semiconductor’s LM317, as an adjustable regulator to only some necessary value of voltage, such as 36 or 3V. This value cannot be less than 1…

A previous Design Idea describes a programmable current source that used a three-terminal National Semiconductor LM317 adjustable regulator (Reference 1). Although that circuit lets you program the output current, the load current flowed through the…