onsemi TN6728A

Overview

TN6728A from Fairchild Semiconductor is a PNP general-purpose amplifier transistor designed for medium-power switching and linear amplification in industrial control and power management circuits, with V_CEO = 60 V, I_C = 1.2 A continuous, and R_θJA = 125 °C/W on FR-4 PCB - enabling robust operation up to +150 °C junction temperature.

For engineers reviewing the TN6728A datasheet, pinout, applications, or equivalent options, this device serves as a high-reliability, thermally stable PNP switch/amplifier where negative-polarity voltage/current handling, low V_CE(sat) at 250 mA, and wide operating temperature range are critical selection criteria.

Technical Context

The TN6728A operates as a silicon PNP bipolar junction transistor fabricated using Process 78, optimized for DC and low-frequency switching applications requiring stable h_FE (80–250 at 50–500 mA) and low saturation voltage (0.35 V at I_C = 250 mA, I_B = 25 mA). Its thermal design supports 1.0 W dissipation at 25 °C ambient with 8 mW/°C derating above that point.

Electrical behavior is defined by negative-polarity ratings: all voltages (V_CEO, V_CBO, V_EBO) and currents (I_C, I_CB0, I_EB0) carry inherent negative polarity per PNP convention, and small-signal gain h_fe = 2.5–25 at 20 MHz confirms suitability for audio and control-loop amplification, not RF.

Key Specifications

Pinout & Package

Package: TO-226 (also known as TO-92 variant, FS PKG Code 95/99) and SOT-223 (FS PKG Code 47) - dual-package availability confirmed in official Fairchild packaging data. Both packages feature emitter-collector-base pinout alignment with flat side orientation reference.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MJD6728 and BC807-40, the TN6728A uniquely balances 60 V voltage rating, 1.2 A current capability, and dual TO-226/SOT-223 package flexibility - making it optimal for cost-sensitive, thermally moderate industrial and automotive control nodes where leaded or compact surface-mount variants are both viable.

Availability

TN6728A is available at Aetrix Electronics and suitable for industrial motor control, DC-DC converter bias circuits, and automotive lighting control requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for TN6728A 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 (now part of ON Semiconductor) is a pioneer in power discrete and analog IC design, specializing in high-reliability silicon solutions for industrial, automotive, and computing markets.

The TN6728A belongs to Fairchild's general-purpose bipolar transistor family engineered for ruggedized medium-power switching and amplification - emphasizing thermal stability, voltage margin, and process consistency across temperature and production lots.

FAQ

What is the maximum continuous collector current rating for TN6728A?

The TN6728A has a maximum continuous collector current (I_C) rating of 1.2 A at T_A = 25 °C, with derating applied above that ambient temperature at 8 mW/°C. This rating is validated for both TO-226 and SOT-223 packages under specified PCB mounting conditions, and the device remains functional up to 1.0 A continuous in typical industrial layouts without forced cooling.

Does TN6728A support operation at elevated temperatures like those found under an automotive hood?

Yes, TN6728A is rated for junction temperatures from –55 °C to +150 °C, and its electrical characteristics - including h_FE, V_CE(sat), and leakage - are guaranteed across this full range. The Safe Operating Area (SOA) curves explicitly include 125 °C and 150 °C conditions, confirming suitability for under-hood automotive applications such as lighting control and sensor interface circuits.

Is TN6728A pin-compatible between TO-226 and SOT-223 packages?

No - while both TO-226 and SOT-223 versions of TN6728A share identical electrical specifications and E-B-C pin order, their physical footprints and soldering requirements differ significantly. TO-226 uses through-hole leads with flat-side orientation; SOT-223 is surface-mount with exposed thermal pad. PCB layout must be redesigned to switch between them.

What is the typical V_CE(sat) of TN6728A under practical switching conditions?

The TN6728A achieves V_CE(sat) = 0.35 V at I_C = 250 mA and I_B = 25 mA, and 0.5 V at I_C = 250 mA and I_B = 10 mA. These values are measured with negative-polarity current flow and reflect real-world saturation performance in medium-power switching applications, directly impacting conduction loss and thermal design.

Can TN6728A be used as a direct replacement for NZT6728?

Yes - TN6728A and NZT6728 are functionally identical devices from Fairchild Semiconductor, sharing identical die, absolute maximum ratings, electrical characteristics, and thermal parameters. The part numbers reflect different ordering channels or packaging variants, but no electrical or reliability differences exist between TN6728A and NZT6728 in production units.