onsemi MPSW45G

Overview

MPSW45G from onsemi is an NPN silicon Darlington transistor in TO-92 package, rated for 1.0 W at TA = 25°C and 2.5 W at TC = 25°C, with V_CEO = 40 V, I_C = 1.0 A, and h_FE ≥ 25,000 at I_C = 200 mA. It serves as a high-gain switching or linear amplification device in low-to-medium power control circuits such as relay drivers and sensor interface stages.

For engineers reviewing the MPSW45G datasheet, pinout, applications, or equivalent options, key selection criteria include its Darlington architecture enabling microampere-level base drive, saturation voltage under load (V_CE(sat) ≤ 1.5 V at I_C = 1.0 A), thermal resistance (R_θJA = 125°C/W), and Pb-free TO-92 packaging compliance.

Technical Context

The MPSW45G implements a monolithic NPN Darlington pair with integrated base-emitter resistor network absent - requiring external base current limiting. Its high DC current gain (h_FE up to 150,000) enables direct drive from logic-level sources, while f_T = 100 MHz supports moderate-frequency switching up to ~10 MHz in optimized layouts.

Thermal design relies on its R_θJC = 50°C/W and R_θJA = 125°C/W ratings; safe operation demands derating above 25°C ambient (8 mW/°C) or case temperature (20 mW/°C). The device exhibits low noise performance (e_n < 2 nV/√Hz at 1 kHz, I_C = 1 mA), making it suitable for low-level analog preamplifier stages where gain stability and noise floor matter.

Key Specifications

Pinout & Package

Package: TO-92 (Case 29−10), Pb-free, through-hole mounting. Standard bent-lead configuration with E-B-C pin order (Pin 1 = Emitter, Pin 2 = Base, Pin 3 = Collector).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMBT4401 and ULN2003A, the MPSW45G uniquely balances ultra-high gain (enabling direct logic drive), moderate power handling (1.0 A), and discrete pin-level control - making it optimal for single-load, high-sensitivity switching where thermal margin and noise performance are prioritized over integration.

Availability

MPSW45G is available at Aetrix Electronics and suitable for relay drivers, sensor interfaces, LED array switches, and thermal cut-off controllers requiring stable component supply, RoHS-compliant packaging, and proven reliability in industrial temperature ranges.

Supply support for MPSW45G 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 MPSW45G belongs to onsemi's legacy discrete bipolar transistor family designed for cost-sensitive, high-reliability linear and switching applications in industrial controls, appliance subsystems, and instrumentation where Darlington gain and thermal robustness are essential.

FAQ

What is the maximum continuous collector current for MPSW45G?

The MPSW45G is rated for 1.0 A of continuous collector current (I_C) at T_A = 25°C. Derating is required above this temperature at 8 mW/°C. At T_C = 25°C, it supports up to 2.5 A transiently, but sustained operation above 1.0 A requires active heatsinking or reduced ambient temperature to maintain junction temperature within −55°C to +150°C limits. The MPSW45G datasheet specifies absolute maximum I_C = 1.0 A for continuous use.

Does MPSW45G have built-in base-emitter resistors?

No, the MPSW45G does not include internal base-emitter resistors. It is a bare Darlington pair requiring external base current limiting - typically a series resistor between the drive source and Pin 2 (Base) to prevent thermal runaway and ensure stable DC bias. This distinguishes it from integrated Darlington arrays like ULN2003A, which embed 2.7 kΩ base resistors. Proper external resistor selection is essential for reliable operation of the MPSW45G.

What is the typical noise voltage of MPSW45G at 1 kHz?

The MPSW45G exhibits a typical input-referred noise voltage (e_n) of less than 2 nV/√Hz at 1 kHz and I_C = 1.0 mA, as confirmed in Figure 2 of the official datasheet. This low noise performance makes the MPSW45G suitable for low-level analog amplification tasks - such as photodiode or thermopile preamplifiers - where preserving signal-to-noise ratio is critical. The MPSW45G achieves this while maintaining high DC gain and thermal stability.

Can MPSW45G replace MPSW45A in existing designs?

The MPSW45G and MPSW45A share identical pinout, package (TO-92), and electrical specifications except for V_CEO and V_CBO: MPSW45G has V_CEO = 40 V and V_CBO = 50 V, while MPSW45A offers 50 V and 60 V respectively. If the application operates below 40 V collector-emitter stress, the MPSW45G is a direct functional replacement. However, designs approaching 45–50 V must verify margin against MPSW45G's lower breakdown ratings before substitution.

What is the thermal resistance junction-to-ambient for MPSW45G?

The MPSW45G has a specified thermal resistance of R_θJA = 125°C/W under standard JEDEC test conditions (single-layer PCB, 1 in² copper pad). This value assumes natural convection and defines the temperature rise per watt dissipated at the die. For example, dissipating 0.8 W results in ~100°C junction-to-ambient rise - requiring careful layout or ambient control to keep T_J ≤ 150°C. The MPSW45G's R_θJC = 50°C/W further enables heatsink attachment if needed.