MMBT3904 Detailed explanation of pin function specifications and circuit principle instructions

The MMBT3904 is a NPN Bipolar Junction transistor (BJT), commonly used in switching and amplification applications. It is manufactured by various semiconductor companies such as ON Semiconductor, Fairchild, STMicroelectronics, etc. It belongs to a series of small-signal transistors.

Packaging Details for MMBT3904:

The MMBT3904 typically comes in the SOT-23 package (a small outline transistor package with three leads), but variations in packaging may occur depending on the manufacturer. The SOT-23 package has three leads or pins:

Collector (C) Base (B) Emitter (E)

This is a three-pin device, so all functions will correspond to these three pins.

Detailed Pin Function Specification:

Pin Number Pin Name Function Explanation 1 Collector (C) Main current carrier from collector to base This pin is where the main current flows out of the transistor. The collector is connected to the load. 2 Base (B) Control current to trigger transistor action This pin controls the current that flows between the collector and the emitter. It is typically connected to a signal source. 3 Emitter (E) Current outflow for the emitter side The emitter is where current flows out of the transistor. It’s connected to ground or a reference voltage in typical setups.

Circuit Principle:

The MMBT3904 operates as an NPN transistor, which means that when a small current is applied to the Base (B), it allows a larger current to flow between the Collector (C) and Emitter (E). This is the basis of transistor amplification and switching.

The Collector is typically connected to a positive voltage source through a load (like a resistor), and the Emitter is connected to ground (or a negative voltage in certain configurations). The Base is driven by a control signal that determines whether the transistor is in an active state or not.

20 Frequently Asked Questions (FAQ) About MMBT3904

Q: What type of transistor is the MMBT3904? A: The MMBT3904 is an NPN Bipolar Junction Transistor (BJT) used for switching and amplification purposes. Q: How many pins does the MMBT3904 have? A: The MMBT3904 has three pins: Collector (C), Base (B), and Emitter (E). Q: What is the maximum current rating for the MMBT3904? A: The MMBT3904 can handle a maximum collector current (Ic) of 200mA. Q: What is the maximum voltage rating for the MMBT3904? A: The maximum collector-emitter voltage (Vce) for the MMBT3904 is 40V. Q: What is the maximum power dissipation of the MMBT3904? A: The maximum power dissipation is 500mW. Q: Can the MMBT3904 be used for high-frequency applications? A: Yes, the MMBT3904 is suitable for high-frequency applications, with a transition frequency (ft) of 250MHz. Q: What is the purpose of the Base pin in the MMBT3904? A: The Base pin controls the transistor's switching action and current flow between the Collector and Emitter. Q: Can the MMBT3904 be used for digital logic circuits? A: Yes, the MMBT3904 can be used for switching and logic circuits, often in low-power digital applications. Q: What is the typical gain of the MMBT3904? A: The DC current gain (hFE) of the MMBT3904 typically ranges from 100 to 300 depending on the operating conditions.

**Q: What is the significance of the *Collector* pin?**

A: The Collector pin is where the larger current flows out of the transistor, and it is connected to the load in most applications.

Q: How do you turn on the MMBT3904 transistor?

A: To turn on the MMBT3904, a small current must be applied to the Base pin, which allows current to flow between the Collector and Emitter.

Q: Can the MMBT3904 be used in high-power circuits?

A: The MMBT3904 is typically used for low-power applications, and it is not suitable for high-power circuits due to its low current and voltage ratings.

**Q: What is the maximum *Base-Emitter voltage (Vbe)* for the MMBT3904?**

A: The maximum Vbe for the MMBT3904 is 5V.

Q: Is the MMBT3904 an analog or digital component?

A: The MMBT3904 is primarily an analog component, often used in amplification and switching applications.

Q: How does the MMBT3904 behave when used as a switch?

A: When used as a switch, the Base is supplied with a control current to switch the transistor on (allowing current to flow between the Collector and Emitter). When the base current is removed, the transistor switches off.

Q: Can I use the MMBT3904 for audio applications?

A: Yes, the MMBT3904 can be used for low-power audio amplification or as part of an audio signal processing circuit.

Q: What is the typical saturation voltage of the MMBT3904 when in the on-state?

A: The typical saturation voltage (Vce(sat)) is about 0.2V when the transistor is fully on.

Q: How should the MMBT3904 be mounted in a circuit?

A: The MMBT3904 is typically mounted in a SOT-23 package with the pins arranged in the following order: Emitter (E), Base (B), and Collector (C), from left to right.

Q: What is the typical frequency response of the MMBT3904?

A: The MMBT3904 has a transition frequency (ft) of 250 MHz, making it suitable for medium-frequency applications.

Q: What are some common applications of the MMBT3904?

A: The MMBT3904 is commonly used in amplifiers, switching circuits, low-power signal amplification, and digital circuits.

Let me know if you need further clarification on any of these points!