1N4148 is a small signal high speed switching diode, also known as a fast recovery diode. It has extremely short recovery time and low reverse leakage current. In electronic circuits, 1N4148 diodes are often used in digital logic circuits, low-frequency amplifiers and other electronic equipment to play rectifier, switch, protection and other functions.

A diode is an electronic device that allows electrical current to flow in only one direction, such as a one-way road where traffic can only travel in one direction or direction. The same goes for the 1N4148 diode, which has been the most popular and best-known silicon diode for many years. The main reasons for its heavy use in electronic products are its interesting specifications and features, small package and low cost. It is available in many different types of packages such as DO-35 glass and many other SMD packages, it is also a fast switching diode with a speed of 4 nanoseconds, 100V reverse, and a maximum power dissipation of 0.5W.

1N4148 diode is mainly used for fast switching purposes, so it is called a switching diode. Its main function is the same as an ordinary switch. The 1N4148 diode has high resistance at a fixed voltage and low resistance above a fixed voltage.

Ⅰ.Specification parameters of 1N4148

•Configuration:Single
•Recovery time:4 ns
•Height:1.91 mm
•Length:4.56 mm
•Width:1.91 mm
•Package/Box:DO-35
•Maximum surge current:4 A
•Vf-forward voltage:1 V
•Ir-reverse current:5 uA
•Vr-reverse voltage:100 V
•Minimum operating temperature:-55℃
•Maximum operating temperature:+175℃
•Peak reverse voltage:100 V
•If-forward current:300 mA
•Thermal resistance:300℃/W (RθJA)
•Installation style:Through Hole
•Current-average rectification (Io):200mA
•Product:General Purpose Diodes
•Product Category:Diodes-General Purpose, Power, Switching
•Voltage-DC reverse (Vr) (maximum):100V
•Voltage at different If - Forward (Vf):1 V @ 10 mA

 

Ⅱ.The role of 1N4148

1.If the reverse connection is connected to the power supply output through the current limiting resistor, the voltage regulation value will be increased. Generally, there will be a voltage drop of 0.45-0.55V after the 1N4148 is turned on. It can be replaced by the common voltage stabilizing diode in reverse series. There are some zener diodes that are not in the series, so the circuit should be a power supply circuit with a voltage between 3.7-3.8V: In addition, if you want to get a more stable voltage regulator, it is best to use the 7805 series of three-terminal modules.

2.In the amplifier circuit, the 1N4148 diode can be used as a current stabilizing diode to ensure stable output of current.

31N4148 is a high-speed switching diode with fast switching speed. When a forward voltage is applied to the P terminal of the diode, it will be in a conductive state, allowing current to pass; and when a reverse voltage is applied to the N terminal of the diode, it will be in a cut-off state, preventing current from passing through. This characteristic allows 1N4148 to be used as a switch in the circuit to control the on and off of the circuit.

4.When converting AC power to DC power, 1N4148 can be used as a rectifier to convert AC signals into unidirectional DC signals.

5.In the circuit, when excessive voltage occurs in the circuit connected to the power supply or other devices, the 1N4148 diode can play a protective role and limit the voltage to a safe range. It responds quickly and cuts off large voltages, protecting electronic equipment from damage.

Ⅲ.Pin configuration of 1N4148

•Pin1 (Anode): This pin allows current to flow
•Pin2 (cathode): current comes from this pin

IV.1N4148 working mode

Diodes work similarly to signal diodes, allowing current to flow in a single direction, from the anode to the cathode. Depending on how it is connected across the voltage source, the 1N414 diode has two modes of operation: forward biased and reverse biased.

•Forward biased mode: In forward biased mode, it operates like a closed switch and allows current to flow through it.

•Reverse bias mode: In reverse bias mode, it operates as an open switch and does not allow current to flow.

Below a specified voltage (cutoff voltage), the diode shows high resistance, above that specific voltage, it shows low resistance.

Ⅴ.Absolute Maximum Ratings of 1N4148
(Values are at TA=25°C unless otherwise noted)

 

Ⅵ.Electrical Characteristics of 1N4148
(Values are at TA=25°C unless otherwise noted)

 

Ⅶ.1N4148 application circuit

1.High frequency amplifier
1N4148 fast recovery diode can be used as an inverter or limiter in high frequency amplifier circuits. In the inverter, the reverse response characteristics of 1N4148 can be amplified and distorted through the inverter circuit; in the limiter, 1N4148 can limit the amplitude range of the input signal to ensure output stability.

2.Inverter
In inverter circuits, 1N4148 can be used as a fast switching element in the drive circuit to help achieve DC to AC conversion. During the operation of the inverter, the 1N4148 diode rapidly switches its on and off states at a high frequency, thus converting DC voltage into AC voltage. When the diode is in the conducting state, current can flow from its anode to the cathode; when the diode is in the off state, the current is blocked. With this fast switching, an AC voltage can be generated at the output.

3.Pulse circuit
1N4148 can be used in pulse circuits, such as pulse generators, pulse modulation, etc. In a pulse generator, the 1N4148 diode uses its fast switching characteristics to generate short pulse signals in the circuit. These pulse signals can be used to trigger other circuit elements, such as transistors or integrated circuits, to achieve specific functions such as timing, control, or communication. In pulse modulation circuits, 1N4148 diodes can also be used to modulate the amplitude, frequency or width of pulse signals. By changing the bias condition of the diode or an external control signal, precise control of the pulse signal can be achieved to meet the needs of a specific application.

4.Detector
The 1N4148 fast recovery diode can be used as a fast-response switch in the detector circuit to achieve sampling and rectification of the input signal. Due to its fast response time, it converts signals efficiently and has low crosstalk and noise.

5.Switch circuit
Since 1N4148 has fast switching characteristics, it can be used as a fast switching component in switching circuits, such as digital logic circuits, power switches, etc. In digital logic circuits, 1N4148 can be used as part of a logic gate (such as AND gate, OR gate, NOT gate, etc.) to implement logic operations by quickly switching its on and off states. For example, in TTL (transistor-transistor logic) circuits, 1N4148 diodes are often used as switching elements in the input and output stages.

6.Sine oscillator
The 1N4148 fast recovery diode can be used as a small signal diode in sinusoidal oscillator circuits. When the signal passes through the capacitor, the 1N4148 suppresses voltage changes within a short period of time, thereby maintaining the stability of the sinusoidal waveform.

7.Protection circuit
1N4148 can be used for over-voltage protection of circuits to prevent over-voltage from damaging other components in the circuit. In protection circuits, 1N4148 diodes are often used as clamping diodes or TVS diodes. When an overvoltage occurs in a circuit, such as due to lightning, electrostatic discharge, or power fluctuations, the 1N4148 diode will quickly conduct and guide the excessive voltage to the ground wire or other safe path. This protects other sensitive components in the circuit from excessive voltage.

8.Rectifier circuit
The 1N4148 can be used as a rectifier element in half-wave or full-wave rectification circuits to convert alternating current to direct current. The rectifier element in the rectifier circuit uses specialized rectifier diodes, such as the 1N4001 to 1N4007 series, which have greater current handling capabilities and are designed specifically for rectification applications. These rectifier diodes conduct when forward biased, allowing current to pass, and cut off when reverse biased, preventing current from passing through.

9.Voltage regulation
The 1N4148 can be used as a voltage regulator component in a circuit to help stabilize the circuit's output voltage. 1N4148 diodes are not typically used for traditional voltage regulation tasks such as voltage regulators. It is mainly a fast switching diode, suitable for high frequency circuits, pulse circuits and switching circuits. However, in some special applications, the diode characteristics of the 1N4148 can be used to implement some simple voltage regulation functions.

10.Mixers and Modems
In some RF circuits, the 1N4148 can be used as a rectifier element in a mixer or modem. 1N4148 diodes can be used as rectifier elements in mixers or modems in radio frequency (RF) circuits, especially when higher frequencies are involved. In a mixer circuit, the 1N4148 diode is used to mix two signals of different frequencies to generate their sum or difference frequency signal. This capability enables it to combine an RF signal with a local oscillator signal to produce the required intermediate frequency (IF) signal.

11.Signal detection
In some circuits, the 1N4148 can be used to detect the presence or absence of a signal, such as a signal detector in some sensor circuits. Due to its fast response and low power consumption, the 1N4148 diode can be used as a signal detector in some circuits, especially in scenarios where it is necessary to quickly determine the presence or absence of a signal. These scenarios typically involve sensor circuits, digital logic interfaces, or any application that requires the detection of changes in voltage or current.

Ⅷ.Advantages of N4148 diodes in switching applications

1.Low conduction voltage drop: The conduction voltage drop of 1N4148 is relatively low, usually between 0.6 and 0.7 volts, which means there will be less power loss in the conduction state.

2.Small size: 1N4148 diodes usually have smaller size and lightweight characteristics, making them suitable for flexible application in various circuit board layouts.

3.Fast switching characteristics: 1N4148 has the characteristics of fast recovery time and short response time, and can quickly transition from on to off state, thereby achieving fast switching operation.

4.High reverse breakdown voltage: 1N4148 has a high reverse breakdown voltage and can withstand large reverse voltages while ensuring safe operation, which enhances its stability and reliability in switching circuits.

5.High cost-effectiveness: 1N4148 is a common and widely used diode. Its low cost and easy availability make it cost-effective in various switching circuits.

 

Frequently Asked Questions

1.Why is 1N4148 commonly used in fast switching applications?
1N4148 is commonly used in fast switching applications due to its fast recovery time and low forward voltage drop, which enables quick switching between conducting and non-conducting states.

2.What type of diode is 1N4148?
1N4148 is a fast switching diode.

3.What is the use of 1N4148?
One-way conduction, replacing Zener diodes, rectifiers, etc.