Design Analysis of Several Constant Current Source Circuits

Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

The constant current source is a power source capable of supplying a constant current to the load, so the application range of the constant current source is very wide and is indispensable in many cases. For example, when the battery is charged by a normal charger, as the battery terminal voltage is gradually increased, the charging current is correspondingly reduced. In order to ensure constant current charging, the output voltage of the charger must be increased at any time. However, after charging with a constant current source, it is not necessary to adjust the output voltage, thereby reducing labor intensity and improving production efficiency. Constant current sources are also widely used in measurement circuits, such as resistance measurement and classification of resistors, measurement of cable resistance, etc., and the more stable the current, the more accurate the measurement.

There are many ways to design a constant current source. The simplest constant current circuit is a FET or a constant current diode, but its current value is limited and its stability is poor. Based on my own experience over the years, this paper discusses the structural principles and characteristics of linear constant current source, switching constant current source and integrated regulator constant current source circuit.

Linear constant current source with integrated op amp

Switching constant current source using switching power supply

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