MMBT4126

The MMBT4126 is a common type of bipolar junction transistor (BJT) known as a single-pole, processed transistor. It is commonly used in applications such as amplifier circuits, switching circuits, analog circuits, and digital circuits. Its operation is based on the principle of controlling current flow between two terminals by varying a voltage applied to control elements within the device.

Background

Bipolar transistors are made of three semiconductor junctions or layers. These are the emitter, collector, and base layers. The primary action of a bipolar junction transistor is to amplify small signals present at the base. By varying the current within the emitter junction, the collector voltage will either increase or decrease, thereby effectively amplifying the collector voltage. The base voltage is usually kept constant.

MMBT4126 Features

The MMBT4126 has a Vce(MAX) of 40 Volts, a Pd of 2 Watts, and an hFE of 40. It is available in both through-hole and surface mount formats, and its operating temperature range is from -65°C to +150°C. It is designed for low frequency applications, and as an NPN transistor it can be used as an amplifier or switch in many applications. Additionally, it is RoHS compliant and lead free.

Application Fields

The MMBT4126 transistor is well suited for a variety of applications. These include audio amplifiers, amplifiers for radio receivers and transmitters, low-noise amplifier stages, small-signal amplifiers, power amplifiers, switching circuits, and digital logic. Other potential applications include high-speed circuits, low-frequency circuits, low-distortion circuits, and linear amplifiers.

Working Principle

The MMBT4126 transistor works by controlling the current flow between two terminals (the collector and the emitter) when a voltage is applied to the base. This means that by varying the voltage applied to the base, the collector current can be varied accordingly. This behavior is referred to as “current gain” or the “transistor function”. The current gain is the ratio of the collector current to the base current and is expressed as hFE (short for common emitter current gain).

The transistor can also work as a switch, which will either allow or prevent current flow between the collector and emitter. This is referred to as saturation, and when the switch is open, this is known as cutoff. To turn the switch “on”, a base current is applied, and to turn the switch off, the base current is removed. Thus, the transistor can be used as an amplifier, a switch, and even as a time delay element.

Conclusion

The MMBT4126 is a bipolar junction transistor (BJT) and can be used in a variety of applications such as amplifiers, switches, and even digital logic. Its operation is based on controlling current flow between two terminals by varying a voltage applied to its base. It is well suited for low-frequency circuits and is RoHS compliant, lead free, and available in both through-hole and surface mount formats.