Onsemi TIP29CG Bipolar Power Transistor: Datasheet, Application Circuits, and Replacement Guide
The Onsemi TIP29CG is a robust NPN bipolar power transistor designed for a wide array of general-purpose amplification and switching applications. As part of the venerable TIP series, it has established itself as a reliable workhorse in power supply circuits, audio amplifiers, and linear regulators. This article provides a detailed overview of its key specifications, practical application circuits, and suitable replacement options.
Datasheet Overview and Key Specifications
The TIP29CG is housed in a TO-220 package, which offers an excellent balance of size and power-handling capability, facilitated by an integral metal tab for easy mounting to a heatsink. Its electrical characteristics define its role in electronic design.
Key absolute maximum ratings from the datasheet include:
Collector-Emitter Voltage (VCEO): 100 V
Collector Current (IC): 1 A (continuous)
Collector Power Dissipation (PD): 30 W at a case temperature (Tc) of 25°C. This value decreases with rising ambient temperature.
DC Current Gain (hFE): Typically 40 to 75 at a collector current of 0.5 A, making it a medium-gain power transistor.
These specifications make it suitable for medium-power tasks where voltages remain below 100V and currents are under 1A.
Application Circuits
1. Linear Voltage Regulator: The TIP29CG is an excellent choice as a pass transistor in linear regulator circuits. In this configuration, a low-current regulator IC (like a 78xx series) controls the base of the TIP29CG, which then handles the high output current required by the load. This dramatically offloads power dissipation from the IC to the more robust transistor and its heatsink.
2. Audio Power Amplifier Output Stage: While not for high-fidelity applications, the TIP29CG is commonly used in the output stage of Class AB amplifiers for small speakers, intercoms, or other audio projects. It is often paired with its PNP complement, the TIP30CG, in a push-pull configuration to efficiently drive the output.
3. General-Purpose Switching: The transistor can be used to switch inductive or resistive loads such as relays, solenoids, or lamps. A crucial design consideration is the use of a flyback diode when switching inductive loads to protect the transistor from voltage spikes generated when the current is suddenly interrupted.
Replacement and Equivalent Guide
Finding a direct replacement for the TIP29CG is generally straightforward due to its common characteristics.
Direct Equivalents: The TIP29C (without the 'G') from other manufacturers is functionally identical. Parts like the NTE181 or MJE3055 are also often listed as suitable substitutes, though a quick cross-reference of the VCEO and current ratings is always advised.
Important Considerations: When replacing, ensure the replacement transistor has a similar or higher VCEO and current rating. Pay close attention to the pinout (Emitter, Base, Collector), as some alternative packages or manufacturers may have a different configuration. The DC current gain (hFE) is another critical parameter to match for linear applications to ensure circuit stability and expected performance.
The Onsemi TIP29CG remains a fundamental component for electronics enthusiasts and professionals alike. Its well-balanced specifications for voltage, current, and power, combined with its versatility in both linear and switching applications, secure its place as a go-to transistor for a multitude of medium-power design challenges.
Keywords:
Bipolar Transistor
Power Transistor
TO-220
Linear Regulator
Switching Circuit
