Constant current source, constant voltage source, voltage drop after MOS is turned on

QWE4562009

Constant current source, constant voltage source, voltage drop after MOS is turned on [Copy link]

Constant current source, constant voltage source, voltage drop after MOS is turned on

1. This is a very classic constant current circuit. The load current is only controlled by the op amp's in-phase input terminal VIN. To determine how much constant current is needed, you only need to control the value of VIN.

If you want the voltage at the load end to be constant (output the desired value), what methods can you use to achieve this?

1. Voltage sampling, closed-loop control, this is one method

2. Although the voltage can be kept constant by using a voltage zener diode, the desired output voltage value cannot be flexibly controlled.

3.

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2. What is the voltage drop between VDS after MOS is saturated and turned on?

Gen_X

According to your requirements, "constant voltage" output is generally adopted, but the current is "limited" to the maximum value.

lkh747566933

I have never made a constant current source. I have always used DCDC and LDO devices. Constant current sources are not suitable for use in analog circuits.

QWE4562009

lkh747566933 posted on 2022-10-29 18:47 I have never made a constant current source. I have always used DCDC and LDO devices. Constant current sources are not suitable for use in analog circuits.

Constant current sources are not suitable for use in analog circuits. How can I say this? Constant current sources are more commonly used in analog circuits, and are even less common in digital circuits.

lkh747566933

QWE4562009 Published on 2022-11-2 15:58 Constant current source is not suitable for use in analog circuits------How to say this, constant current source is still used more in analog circuits, and it is even less seen in digital circuits...

I made a typo. Constant current sources are usually used in analog circuits. I am making digital circuits, and simulation is too difficult.

jiafei2020

Good, very useful reference