onsemi MPSA28_D26Z

Overview

MPSA28_D26Z from ON Semiconductor is an NPN silicon Darlington transistor optimized for high-current switching and amplification in low-frequency analog and power control circuits, featuring V_CEO = 80 V, I_C = 500 mA, h_FE ≥ 10,000 at 10 mA, V_CE(sat) ≤ 1.2 V, and TO-92 (CASE 29–11) packaging - used in relay drivers, lamp dimmers, and industrial sensor interface stages.

For engineers reviewing the MPSA28_D26Z datasheet, pinout, applications, or equivalent options, key selection criteria include guaranteed DC current gain at low base drive, thermal resistance (R_θJA = 200°C/W), safe operating area limits, emitter-base breakdown voltage (V_EBR = 12 V), and compatibility with legacy through-hole PCB layouts requiring discrete high-gain switching.

Technical Context

The MPSA28_D26Z implements a monolithic two-stage NPN Darlington configuration that delivers ultra-high DC current gain without external bias network complexity. Its internal structure enables stable operation under sustained 500 mA collector current with junction temperature up to +150°C and supports linear-mode amplification with f_T = 125 MHz at 10 mA.

It operates with fixed terminal polarity: Emitter (Pin 1), Base (Pin 2), Collector (Pin 3), and requires no external emitter resistor for basic saturation switching. The device exhibits low leakage (I_CBO ≤ 100 nA at 60 V) and predictable V_BE(on) = 1.4–2.0 V across its rated current range.

Key Specifications

Pinout & Package

Package: TO-92 (CASE 29–11, TO–226AA), epoxy molded, through-hole mountable with 2.54 mm lead pitch and 6.35 mm body length.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Darlington transistor applications.

Compared with MPSA29_D26Z and ULN2003A, the MPSA28_D26Z delivers the best combination of ultra-high gain, minimal base drive, and lowest unit cost for single-point high-current switching - especially where discrete layout, thermal isolation, or absence of integrated clamping is required.

Availability

MPSA28_D26Z is available at Aetrix Electronics and suitable for relay drivers, lamp dimmers, sensor amplifiers, and industrial solenoid controllers requiring stable component supply across long-lifecycle industrial programs.

Supply support for MPSA28_D26Z 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

ON Semiconductor is a global semiconductor supplier delivering energy-efficient, high-performance silicon solutions for automotive, industrial, cloud computing, and consumer electronics markets.

The MPSA28_D26Z belongs to ON Semiconductor's general-purpose bipolar transistor product line, engineered specifically for cost-sensitive, high-reliability discrete switching and linear amplification in legacy and new-design through-hole applications.

FAQ

What is the maximum continuous collector current rating for MPSA28_D26Z?

The MPSA28_D26Z is rated for 500 mA continuous collector current (I_C) at T_A = 25°C. Derating applies above 25°C at 5.0 mW/°C for ambient-limited operation or 12 mW/°C when case-mounted. At T_C = 25°C, it supports 1.5 W dissipation - making it suitable for pulsed loads exceeding 500 mA if duty cycle and thermal path permit. Always verify actual board-level thermal performance using R_θJA = 200°C/W.

Does MPSA28_D26Z have a built-in base-emitter resistor?

No, the MPSA28_D26Z does not include any internal base-emitter resistor. It is a bare Darlington transistor requiring external base current limiting - typically a 10 kΩ to 47 kΩ resistor between MCU GPIO and Pin 2 (Base) to ensure proper saturation and prevent overdrive. This differs from integrated driver arrays like ULN2003A, which embed 2.7 kΩ base resistors. External resistor selection must account for V_BE(on) = 1.4–2.0 V and target I_B ≈ I_C/1000.

Can MPSA28_D26Z replace MPSA13 in existing designs?

Yes, MPSA28_D26Z can functionally replace MPSA13 in most applications due to identical TO-92 package, pinout (E-B-C), and NPN Darlington topology. However, MPSA28_D26Z offers higher V_CEO (80 V vs. 30 V), higher I_C (500 mA vs. 300 mA), and significantly higher h_FE (≥10,000 vs. ≥1,000), improving drive efficiency and noise immunity. Verify that increased gain does not cause instability in linear amplifier configurations before drop-in substitution.

What is the safe operating area (SOA) limitation for MPSA28_D26Z at 25°C case temperature?

At T_C = 25°C, the MPSA28_D26Z supports up to 1.5 W total dissipation, corresponding to a safe operating area bounded by I_C ≤ 500 mA and V_CE ≤ 3.0 V for DC operation. For pulse conditions, Figure 5 in the ON Semiconductor datasheet shows second breakdown limits - e.g., 100 mA at 80 V is permissible only for ≤1 ms pulses at 10% duty cycle. Always consult the published SOA curve (MPSA28/D, page 3) for time-varying load profiles.

Is MPSA28_D26Z suitable for linear amplification or only switching?

The MPSA28_D26Z is qualified for both linear amplification and switching use. Its specified f_T = 125 MHz, low distortion at I_C = 10–100 mA, and stable h_FE across current range support audio preamplifier and sensor signal conditioning roles. However, due to Darlington architecture, it exhibits higher V_BE (~1.6 V) and slower turn-off than single transistors - so avoid in high-fidelity or high-speed analog paths. Use only where gain and simplicity outweigh bandwidth constraints.