onsemi MPSA77RLRAG

Overview

MPSA77RLRAG from onsemi is a PNP silicon Darlington transistor in TO-92 package, rated for −60 V V_CE, −500 mA I_C, and 625 mW power dissipation at 25°C, with h_FE ≥ 10,000 at −10 mA/−5 V - used in high-gain switching and linear amplification stages of industrial control interfaces and relay drivers.

For engineers reviewing the MPSA77RLRAG datasheet, pinout, applications, or equivalent options, key selection criteria include guaranteed DC current gain at low base drive, V_CE(sat) ≤ −1.5 V under −100 mA load, −60 V breakdown margin, Pb-free tape-and-reel packaging (2,000 units), and thermal resistance of 200°C/W for ambient-limited PCB layouts.

Technical Context

The MPSA77RLRAG integrates two cascaded PNP transistors in a single TO-92 package to achieve ultra-high DC current gain (h_FE ≥ 10,000) while maintaining V_CE(sat) ≤ −1.5 V at I_C = −100 mA and I_B = −0.1 mA. Its −60 V V_(BR)CES rating supports operation in higher-voltage DC control rails up to −48 V.

Designed for low-base-drive switching, it delivers V_BE(on) ≤ −2.0 V at −100 mA collector current and exhibits usable high-frequency gain (|h_fe| ≥ 1.25) at 100 MHz under −10 mA bias - enabling stable performance in pulse-width modulated (PWM) output stages and analog signal buffering.

Key Specifications

Pinout & Package

Package: TO-92 (Case 29-11, Style 1), Pb-free, tape-and-reel (2,000 units). Standard lead configuration with emitter (pin 1), base (pin 2), collector (pin 3).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MPSA77RLRAG, MPSA77RLRA offers identical performance but lacks Pb-free compliance, while PN2907A trades ultra-high gain for lower cost and broader availability - making MPSA77RLRAG optimal for space- and drive-current-constrained designs requiring RoHS adherence.

Availability

MPSA77RLRAG is available at Aetrix Electronics and suitable for industrial relay drivers, low-power analog amplifiers, LED current regulators, and power supply enable switches requiring stable component supply and RoHS-compliant packaging.

Supply support for MPSA77RLRAG 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 manufacturer specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The MPSA75/MPSA77 series was designed specifically for high-gain, medium-voltage PNP switching and amplification in space-constrained industrial control and interface circuits - emphasizing reliability, manufacturability, and Pb-free compliance.

FAQ

What is the maximum collector-emitter voltage rating for the MPSA77RLRAG?

The MPSA77RLRAG has a guaranteed minimum collector-emitter breakdown voltage V_(BR)CES of −60 V at I_C = −100 µA and V_BE = 0. This rating ensures reliable operation in −48 V DC systems with margin for transient spikes. Exceeding −60 V risks avalanche breakdown and permanent device damage. Always reference the absolute maximum ratings table in the official onsemi datasheet for derating curves above 25°C ambient.

Does the MPSA77RLRAG require a base current limiting resistor when driven by a microcontroller GPIO?

Yes, the MPSA77RLRAG requires an external base current limiting resistor when driven directly from a microcontroller GPIO. Although its h_FE ≥ 10,000 allows very low base current, the base-emitter junction behaves like a diode with V_BE(on) ≈ −2.0 V. Without current limiting, excessive base current can exceed the −100 mA I_C test condition and cause thermal overstress. Typical designs use 1–10 kΩ resistors depending on GPIO voltage and desired collector current.

Is the MPSA77RLRAG pin-compatible with the MPSA75RLRAG?

No, the MPSA77RLRAG is not functionally interchangeable with the MPSA75RLRAG despite identical TO-92 packaging and pinout. The MPSA75RLRAG has a lower V_(BR)CES rating of −40 V and shares the same h_FE and I_C specs, but substituting it in −48 V applications risks premature breakdown. Always verify voltage requirements before replacement - the MPSA77RLRAG is specified for higher-voltage operation.

What is the thermal resistance junction-to-ambient (R_θJA) for the MPSA77RLRAG in standard TO-92 mounting?

The MPSA77RLRAG has a specified thermal resistance R_θJA of 200°C/W under standard test conditions (JEDEC JESD51-2, 1 in² copper pad, no airflow). This value assumes minimal PCB copper area and natural convection cooling. In practice, adding thermal relief traces or increasing copper area can reduce effective R_θJA by 20–40%. For continuous 625 mW operation, ambient temperature must remain below +75°C to keep junction temperature within the −55°C to +150°C range.

Can the MPSA77RLRAG be used in linear amplifier configurations?

Yes, the MPSA77RLRAG can be used in linear amplifier configurations such as emitter followers or Class-A stages, provided operating conditions stay within Safe Operating Area (SOA) limits. Its high h_FE and low V_CE(sat) support stable DC biasing, but power dissipation must be managed carefully - e.g., at V_CE = −5 V and I_C = −50 mA, P_D = 250 mW, well within the 625 mW limit. Always consult Figure 5 (SOA plot) in the onsemi datasheet to avoid second breakdown.