onsemi TN6727A

Overview

TN6727A from Fairchild Semiconductor is a PNP general-purpose bipolar junction transistor designed for medium-power amplification and switching applications, with 1 A continuous collector current capability, 40 V collector-emitter breakdown voltage (BV_CEO), and 50 °C/W junction-to-case thermal resistance - deployed in motor drive stages and DC-DC converter control circuits.

For engineers reviewing the TN6727A datasheet, pinout, applications, or equivalent options, key selection criteria include verified DC current gain (h_FE = 55–250 at I_C = 10 mA–1 A), saturation voltage (V_CE(sat) = 0.5 V @ I_C = 1 A, I_B = 100 mA), and TO-226 package compatibility with through-hole PCB layouts.

Technical Context

The TN6727A operates as a silicon PNP BJT with fixed emitter-base and collector-base junction structures optimized for linear amplification and hard-switching duty. Its h_FE spans 55 to 250 across I_C = 10 mA–1 A, and V_BE(on) is specified at 1.2 V under I_C = 1 A, V_CE = 1 V conditions.

Thermal design is constrained by R_θJC = 50 °C/W and R_θJA = 125 °C/W, requiring heatsinking for sustained >500 mW dissipation. Absolute maximum ratings include T_J = 150 °C, V_CBO = 50 V, and V_EBO = 5 V - limiting use in high-voltage bias networks or reverse-biased emitter configurations.

Key Specifications

Pinout & Package

Package: TO-226 (also known as TO-92), plastic through-hole package with 3 leads, standardized lead spacing (0.1 inch), and epoxy body rated for 150 °C junction temperature operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MJD2955 and BC557, the TN6727A uniquely balances 1 A switching capability, TO-226 mechanical compatibility, and 0.5 V saturation voltage - making it optimal for space-constrained, medium-power applications where neither low-signal nor high-power alternatives meet all requirements.

Availability

TN6727A is available at Aetrix Electronics and suitable for motor control stages, DC-DC converter feedback loops, relay driver circuits, and power supply sequencing applications requiring stable component supply and long-term industrial availability.

Supply support for TN6727A 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 manufacturer specializing in power management, analog, and discrete components before its acquisition by ON Semiconductor in 2016.

The TN6727A belongs to Fairchild's legacy general-purpose bipolar transistor family, engineered for cost-sensitive, medium-power linear and switching applications in industrial controls and power supplies.

FAQ

What is the maximum continuous collector current rating for the TN6727A?

The TN6727A has a maximum continuous collector current (I_C) rating of 1.5 A at T_A = 25°C. However, its recommended operating limit is 1 A under typical conditions to maintain reliability and thermal stability. Derating applies above 25°C ambient - 8 mW/°C - and actual usable current depends on PCB copper area, airflow, and heatsinking. The TN6727A datasheet specifies V_CE(sat) and h_FE performance up to 1 A, confirming its design intent for that load level.

Is the TN6727A pin-compatible with other TO-226 PNP transistors like the BC557 or 2N3906?

The TN6727A uses the standard TO-226 (TO-92) package with E-B-C lead order (viewed from flat side, leads down), matching BC557 and 2N3906 mechanical pinout. However, electrical characteristics differ significantly: TN6727A supports 1 A I_C versus 100 mA for BC557, and its h_FE range (55–250) is narrower than 2N3906 (100–300). So while footprint-compatible, TN6727A is not a direct electrical substitute without circuit validation.

What is the typical V_CE(sat) of the TN6727A and under what conditions is it specified?

The TN6727A exhibits a typical collector-emitter saturation voltage (V_CE(sat)) of 0.5 V when operated at I_C = 1 A and I_B = 100 mA, with V_CE = 1 V. This value is measured under pulsed test conditions (≤300 µs pulse width, ≤1.0% duty cycle) per the datasheet. In continuous DC operation, V_CE(sat) may rise slightly due to self-heating, especially without heatsinking - making the 0.5 V figure a key benchmark for low-loss switching design using the TN6727A.

Does the TN6727A have built-in protection features such as thermal shutdown or overcurrent limiting?

No, the TN6727A is a discrete silicon PNP bipolar junction transistor with no integrated protection circuitry. It lacks thermal shutdown, overcurrent limiting, or ESD protection diodes. External design measures - including base current limiting, collector snubbers, flyback diodes for inductive loads, and heatsinking - are required to ensure safe operation. The TN6727A datasheet specifies absolute maximum ratings (e.g., T_J ≤ 150°C, V_CEO ≤ 40 V) but does not include any active protection mechanisms.

Can the TN6727A be used in linear amplifier configurations, and what is its small-signal current gain?

Yes, the TN6727A supports linear amplifier use, with a small-signal current gain (h_fe) of 25 at I_C = 50 mA, V_CE = 10 V, f = 20 MHz. Its h_FE varies from 55 to 250 depending on collector current and bias point, providing usable gain across mid-frequency audio and control loop bandwidths. For stable linear operation, proper biasing, emitter degeneration, and thermal stabilization are required - as with any discrete BJT. The TN6727A is not optimized for RF or high-fidelity audio but performs reliably in instrumentation and feedback amplifier roles.