Efficient BJT Constant Current Source for Precise Current Regulation

In summary, the conversation discusses the need for a constant current source circuit with specific requirements such as a range of 0.1 to 1mA, +/-1% tolerance, and Vcc of 3.3v. Suggestions are made to use a single transistor with a load in the collector circuit and an inverting opamp with a rail-to-rail amplifier. The idea of using a low voltage voltage reference using a constant current source is also mentioned. Additional resources are provided for further information on creating a bigger current source and using a voltage reference chip.
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  • #2
A good starting point would be a single transistor with you load in the collector circuit.
The current would be set with the bias voltage at the base (eg 1.7V) and the value of the emitter resistance (eg 1k).
This would give an emitter and collector current of more or less I = 1V/1k...1mA
 
  • #3
  • #4
I should have mentioned before. My load is connected to ground.
I am trying to make a low voltage(0.2v or 0.3v), voltage reference using constant current source.
I could use a standard voltage ref and divide it using resistors. But I thought using current source would be cool.
There are a few voltage ref chips available with low voltage. But I am more interested in the current source.
 

Related to Efficient BJT Constant Current Source for Precise Current Regulation

1. What is a constant current source?

A constant current source is an electronic circuit that is designed to provide a steady and consistent output current, regardless of changes in load resistance or input voltage. It is commonly used in various applications, such as LED lighting, battery charging, and precision measurement devices.

2. How does a constant current source work?

A constant current source works by using a negative feedback loop, where a sensing resistor is used to measure the output current and adjust the circuit accordingly to maintain a constant current. This can be achieved through various circuit configurations, such as using operational amplifiers or transistors.

3. What are the benefits of using a constant current source?

Using a constant current source can provide several benefits, such as ensuring the stability and accuracy of the output current, protecting the load from overcurrent, and improving the overall efficiency of the circuit. It also allows for better control and regulation of the current, making it ideal for powering sensitive devices.

4. What are the differences between a constant current source and a constant voltage source?

A constant current source provides a steady current output, while a constant voltage source provides a steady voltage output. In a constant current source, the voltage varies depending on the load resistance, while in a constant voltage source, the current varies. Additionally, a constant current source is used to power devices that require a specific current, while a constant voltage source is used for devices that require a specific voltage.

5. What are some common applications of a constant current source?

A constant current source is commonly used in LED lighting to ensure a consistent and efficient current flow to the LEDs. It is also used in battery charging circuits to prevent overcharging and in precision measurement devices to provide accurate current for testing and calibration. Other applications include powering lasers, electromagnets, and various electronic devices that require a steady and regulated current.

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