onsemi PN5138

Overview

PN5138 from Fairchild Semiconductor is a PNP general-purpose bipolar junction transistor (BJT) designed for amplification and switching applications with continuous collector current up to 500 mA and V_CEO = 30 V. It operates across –55°C to +150°C, features h_FE ≥ 50 at I_C = 10 mA, V_CE = 10 V, and is housed in a TO-92 plastic package. It is commonly used in low-voltage DC switching circuits and signal amplification stages.

For engineers reviewing the PN5138 datasheet, pinout, applications, or equivalent options, key selection considerations include its PNP polarity, 30 V breakdown rating, 500 mA I_C capability, thermal resistance of 200°C/W (J-A), and saturation voltage of 0.3 V at I_C = 10 mA / I_B = 0.5 mA - all critical for discrete power and signal control designs.

Technical Context

The PN5138 is a silicon planar epitaxial PNP BJT fabricated using Fairchild's Process 68. Its structure supports linear amplification and saturated switching, with verified DC current gain (h_FE) ranging from 50 to 800 depending on operating point, and guaranteed V_(BR)CEO ≥ 30 V at I_C = 10 mA.

Small-signal parameters include h_fe = 40 at 1 kHz (I_C = 1 mA, V_CE = 10 V) and input/output capacitances of C_ib = 30 pF and C_ob = 7.0 pF, confirming suitability for audio-frequency and low-speed digital switching applications.

Key Specifications

Pinout & Package

PN5138 is packaged in a standard through-hole TO-92 case with three leads. Pin identification follows JEDEC TO-92 outline: flat side facing viewer, leads down, left-to-right = Emitter (E), Base (B), Collector (C). Mechanical dimensions conform to Fairchild's TO-92 specification (Rev. B, Jan 2000).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP general-purpose amplifier applications.

Compared with MPSA92 and PN2907, PN5138 offers superior h_FE consistency above 500 mA and lower V_CE(sat), making it optimal for precision current-controlled switching and medium-gain amplification where thermal headroom and gain stability are prioritized.

Availability

PN5138 is available at Aetrix Electronics and suitable for industrial control systems, automotive body electronics, and consumer audio equipment requiring stable component supply and long-term manufacturability.

Supply support for PN5138 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and discrete devices before its acquisition by ON Semiconductor in 2016.

The PN5138 belongs to Fairchild's general-purpose bipolar transistor product line, engineered for cost-effective, reliable amplification and switching in non-critical industrial and consumer applications.

FAQ

What is the maximum continuous collector current rating for PN5138?

The PN5138 has a maximum continuous collector current (I_C) rating of 500 mA at T_A = 25°C. This value decreases with rising ambient temperature due to thermal derating - at 100°C, the usable I_C drops to approximately 312 mA based on its 5.0 mW/°C derating factor. Always verify thermal design margins when operating near this limit in the final PN5138 application.

Is PN5138 a PNP or NPN transistor?

PN5138 is a PNP bipolar junction transistor. Its absolute maximum ratings, electrical characteristics table, and pinout configuration (Emitter-Base-Collector order in TO-92) all confirm PNP polarity. This means it conducts when the base is driven negative relative to the emitter, and current flows from emitter to collector - a key distinction from NPN types like the PN2222. The PN5138 datasheet explicitly states "PNP General Purpose Amplifier" in its title.

What is the typical V_CE(sat) for PN5138 under standard test conditions?

The typical collector-emitter saturation voltage (V_CE(sat)) for PN5138 is 0.3 V when tested at I_C = 10 mA and I_B = 0.5 mA. This low saturation voltage minimizes power dissipation during switching operation and improves efficiency in DC load control circuits. The PN5138 datasheet lists this value as a maximum, confirming consistent performance across production lots.

Does PN5138 have a specified junction-to-case thermal resistance?

Yes, PN5138 specifies R_θJC = 83.3°C/W in its Thermal Characteristics table. This parameter reflects the thermal resistance between the silicon die junction and the TO-92 package case surface, and is essential for estimating temperature rise when using a heatsink or metal mounting tab. For PCB-only mounting, R_θJA = 200°C/W is the more relevant metric for PN5138 thermal design.

Can PN5138 be used as a direct replacement for PN2907 in existing designs?

PN5138 can serve as a functional alternative to PN2907 in many applications, but it is not a drop-in replacement due to differences in h_FE distribution and V_CE(sat). While both are TO-92 PNP transistors rated for 30 V and 500–600 mA, PN5138 offers higher minimum h_FE (50 vs. 100 for PN2907) and lower saturation voltage (0.3 V vs. 0.4–1.0 V). Verify bias network compatibility and thermal margin before substituting PN5138 in a PN2907-based design.