onsemi MPSW45AG

Overview

MPSW45AG from onsemi is an NPN silicon Darlington transistor in a TO-92 package, rated for 1.0 W at TA = 25°C and 2.5 W at TC = 25°C, with V_CEO = 50 V, I_C = 1.0 A, and h_FE ≥ 4,000 at I_C = 1.0 A. It delivers high DC current gain and low saturation voltage for low-power switching and amplification in industrial control interfaces and relay drivers.

For engineers reviewing the MPSW45AG datasheet, pinout, applications, or equivalent options, key selection criteria include its Darlington configuration enabling high-current drive with minimal base current, thermal resistance (R_θJA = 125°C/W), noise performance at low frequencies, and Pb-free TO-92 packaging suitable for through-hole assembly in cost-sensitive embedded systems.

Technical Context

The MPSW45AG implements a monolithic NPN Darlington pair with integrated base-emitter resistor network, optimized for high h_FE (up to 150,000 at low I_C) and stable gain across collector currents from 0.2 A to 1.0 A. Its f_T = 100 MHz supports moderate-speed switching while maintaining low V_CE(sat) ≤ 1.5 V and V_BE(sat) ≤ 2.0 V under I_C/I_B = 500.

Thermal design relies on R_θJC = 50°C/W and R_θJA = 125°C/W, with safe operating area (SOA) limited by second breakdown above 10 V and 100 mA in single-pulse mode. Noise characteristics are specified down to 10 Hz, with en ≈ 0.5 nV/√Hz at RS = 1 kΩ and IC = 1 mA.

Key Specifications

Pinout & Package

Package: TO-92 (Case 29-10), Pb-free, through-hole mounting. Pin 1 = Emitter, Pin 2 = Base, Pin 3 = Collector (Style 1 per onsemi mechanical drawing).

Key Features

Applications

Equivalent & Alternatives

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

Compared with ULN2003A and BD679A, the MPSW45AG provides optimal balance of single-device simplicity, TO-92 compactness, and 1 A capability-making it ideal for cost-sensitive, space-constrained designs where discrete Darlington performance is needed without array complexity or heatsink dependency.

Availability

MPSW45AG is available at Aetrix Electronics and suitable for industrial relay drivers, low-voltage motor control, sensor signal amplification, and LED array drivers requiring stable component supply and RoHS-compliant through-hole assembly.

Supply support for MPSW45AG 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power management, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The MPSW45AG belongs to onsemi's legacy discrete transistor portfolio designed specifically for robust, low-cost switching and amplification in industrial control, instrumentation, and appliance applications where reliability and thermal stability are critical.

FAQ

What is the maximum continuous collector current rating for the MPSW45AG?

The MPSW45AG is rated for 1.0 A continuous collector current (I_C) at ambient temperature T_A = 25°C with appropriate PCB copper area. Derating applies above 25°C at 8 mW/°C for ambient-limited operation, and the device supports up to 2.5 W dissipation when case temperature is maintained at 25°C-enabling higher current in heatsinked or thermally enhanced layouts. This rating is confirmed in the Absolute Maximum Ratings table of the official onsemi datasheet MPSW45/D.

Does the MPSW45AG have built-in protection features such as clamp diodes or thermal shutdown?

No, the MPSW45AG does not integrate clamp diodes, thermal shutdown, or current limiting circuitry. It is a bare monolithic Darlington transistor requiring external flyback diodes across inductive loads (e.g., relays or solenoids) and careful thermal design due to its R_θJA = 125°C/W. Protection must be implemented externally per application requirements-consistent with its role as a fundamental discrete switching element rather than a protected smart power device.

What is the guaranteed minimum DC current gain (h_FE) of the MPSW45AG at 1.0 A collector current?

The MPSW45AG guarantees h_FE ≥ 4,000 at I_C = 1.0 A, V_CE = 5.0 V, and T_A = 25°C, as specified in the Electrical Characteristics table of the onsemi datasheet MPSW45/D. This high gain enables microcontroller GPIO pins to directly drive the base with ≤250 µA, eliminating need for additional driver transistors in many low-speed switching applications.

Can the MPSW45AG be used in linear amplifier configurations, and what noise performance can be expected?

Yes, the MPSW45AG is characterized for low-frequency noise performance and is suitable for linear amplifier use. At I_C = 1.0 mA and R_S = 1 kΩ, its input-referred voltage noise (e_n) is approximately 0.5 nV/√Hz at 1 kHz, as shown in Figure 2 of the MPSW45/D datasheet. This makes it viable for precision sensor buffering and low-noise preamplifier stages where Darlington gain and noise trade-offs are favorable over standard BJTs.

Is the MPSW45AG pin-compatible with the older MPSW45 or MPSW45A variants?

Yes, the MPSW45AG shares identical TO-92 pinout (Emitter-Base-Collector, Style 1), package dimensions, and electrical specifications with MPSW45 and MPSW45A-except that MPSW45AG is Pb-free (marked with "G") and rated for V_CEO = 50 V like MPSW45A. The "G" suffix denotes RoHS compliance but does not alter pin assignment, footprint, or functional behavior, allowing direct substitution in existing designs without layout changes.