Manufactured by ON Semiconductor, the MMBT2222ALT1G is an NPN bipolar transistor that allows circuits to manage high levels of voltage. It is specifically intended for switching, as well as for linear lower power surface mount applications. MMBT2222ALT1G is BFR and Halogen-free, RoHS-compliant, and Pb-free. 

MMBT2222ALT1G Diagram

What is a Transistor?

If our brains have neurons that help us remember things and think, computers have small “brain cells” that help them function well. These brain cells are known as transistors, which are mini electronic devices invented more than 50 years ago.

A transistor can function as a switch and an amplifier.

  • Transistor as a switch – If the transistor base has a positive signal, it acts as a closed switch and turns ON. If there is no signal applied to the base, the transistor functions as an open switch and turns OFF. As such, there is zero flow of current.
  • Transistor as an amplifier – As an amplifier, the transistor works like a current booster. In one end, it receives small electric currents (input currents) and on the other end, it gives out larger electric currents (output currents). This transistor function is an essential factor for certain products, particularly for hearing aids, which has tiny microphones and loudspeakers.

A transistor is created using the chemical element silicon, which is found in sand. Although it is normally not capable of conducting electricity, there are certain elements (such as phosphorous and arsenic) that may be added to treat its impurities. 

Transistor” came from the words “trans” and “istor”. Trans is short for transfer property while istor refers to the resistance property that’s offered to junctions. Put together, transistor means a device for switching that amplifies and regulates electrical signals, such as current and voltage.

Transistors like the MMBT2222ALT1G are semiconductors.  ON Semiconductor’s transistor is also an NPN transistor, which means the emitter and collector are reverse-biased (open when base is at ground) and forward-biased (closed when base pin has signal). You can read more about how transistors work on explain that stuff. 

The MMBT2222ALT1G transistor, like the 2N2222A transistor, is intended for controlling low current loads through various switching circuits. 

MMBT2222ALT1G Applications, Specifications, and Features

The MMBT2222ALT1G is essential for the following applications:

  • Controlling motor speed
  • Rectifier and inverter circuits
  • LED driver, Relay driver, and other driver modules
  • Darlington Pair Designs
  • Load switching to up to 600mA

Technical specifications:

  • -55°C to 150°C operating temperature
  • 100@150mA, 10V DC current gain
  • 1V@50mA, 500mA maximum Vce Saturation
  • 600mA maximum current-collector
  • Maximum power = 225mW
  • Maximum voltage-collector emitter breakdown = 40V
  • Surface mount


  • NPN bipolar transistor (small signal)
  • IC or continuous collector current
  • hFE or DC current gain (100-300)
  • VCE collector emitter voltage
  • VBE emitter base voltage
  • 25ns rise time and 60ns fall time
  • Lead-free
  • BFR and Halogen-free
  • Compliant with Restriction of Hazardous Substances Directive (RoHS)

As mentioned earlier, the MMBT2222ALT1G is manufactured by ON Semiconductor, a Fortune 1000 company that supplies semiconductors to various industries. Some of their products are power applications, signal and power management, LED lighting, automotive custom devices, and medical devices, among others. The MMBT2222ALT1G is under the company’s lineup of Discrete products.