1N4148 is a small high-speed switching diode, which switches quickly. It is widely used for unidirectional isolation of circuits with higher signal frequencies, such as communications, computer boards, television circuits, and industrial control circuits.

Features

A very versatile high-frequency switching diode. Including DO35, LL34, SOD323, SOT23, 0805 packages are available.

With 75V reverse withstand voltage and 150mA average forward current, it is very suitable for general rectification in general occasions.

The junction capacitance of 4pF and the reverse recovery time of 4nS are sufficient for most occasions.

A small signal high-frequency diode that is very easy to obtain, inexpensive, and has a wide range of versatility.

What is the purpose of 1N4148 reversed connection with 3.3V, voltage regulation, reverse conduction?

Effect

Another: If I want to make the 5V output voltage more stable, can I connect a 5V Schottky diode in parallel to the output phase?

Answer 1. After the reverse connection is connected to the power supply output through the current limiting resistor (please describe it clearly), it will increase the voltage regulation value. Generally, there will be a voltage drop of 0.45-0.55V after 1N4148 is turned on. After the zener diode is reversed, it can replace some zener diodes that are not in the series, so the circuit should be a power supply circuit with a regulated voltage between 3.7-3.8V; if you want to get a more stable regulated power supply, it is best to use the 7805 series The three-terminal model is fast,

Answer 2. If it is connected in reverse with 3.3V in series, it may be to prevent 3.3V from flowing back into other circuits.

Answer 3. 1N4148 is an ordinary diode, mainly used for unidirectional conduction. 1N4148 is reversely connected to 3.3V, depending on what line it is on. It may be rectified to 3.3V by another voltage; or signal clamp protection. When the signal voltage exceeds 3.3V, the diode is turned on. In the switching power supply, it is useless to increase the Schottky diode in antiphase and parallel connection, and the output can be stabilized by increasing the capacitance.

Answer 4. Generally, it is anti-static. In addition to preventing clean electricity, it can also protect other circuits (such as MCU) when the power supply is reversed.

Answer 5. What I have seen is generally in the reset (resistance-capacitance) circuit. Does it play a protective role when it is powered on?

Answer 6. The diode in the Reset circuit speeds up the discharge of the capacitor.

Answer 7. 1N4148 is a general diode with unidirectional conductivity. In addition to the functions mentioned above, it can also be used for rectification.

Answer 8. Are the two in series or in parallel? If it is connected in series, it will improve thermal stability, so that the voltage regulation value will not change due to changes in operating current and temperature. If it is connected in reverse and parallel connection, it seems that it has not been used in this way. It can only be used as a 0.5~0.7V voltage regulator tube. It is not necessary.

Answer 9. Ordinary diodes can be used for voltage stabilization, clamping and unidirectional conduction, and can be used as an anti-backflow protection circuit for inductive devices.

Answer 10. Increase the stabilized voltage, the stabilizer tube 3.7V+4148 can be used as a 4.3 stabilized tube.

Answer 11. 1N4148 is a fast recovery diode for protection. Such as level inversion or induced electromotive force. If it is a high-frequency induced electromotive force, a Schottky diode is required.