onsemi MPSA77_D75Z

Overview

MPSA77_D75Z from ON Semiconductor (formerly Fairchild) is a PNP Darlington transistor optimized for high-current-switching applications requiring minimum base drive and extremely high DC current gain (h_FE ≥ 10,000 at I_C = −100 mA). It supports continuous collector current up to −1.2 A, V_CE(sat) ≤ −1.5 V, and operates across −55°C to +150°C junction temperature. Used in relay drivers, lamp drivers, and low-frequency power switching circuits.

For engineers reviewing the MPSA77_D75Z datasheet, MPSA77_D75Z pinout, MPSA75_D75Z application, or MPSA77_D75Z equivalent, key selection criteria include guaranteed h_FE ≥ 10,000 at −100 mA, V_CE(sat) ≤ −1.5 V under specified drive, TO-92 mechanical compatibility, thermal resistance R_θJA = 200°C/W, and −60 V V_CEO rating for robust voltage margin in industrial control designs.

Technical Context

The MPSA77_D75Z implements a monolithic PNP Darlington pair with integrated base-emitter resistor network absent - external base biasing required. Its high h_FE enables direct microcontroller GPIO driving without additional pre-amplification stages. The device uses process 61, optimized for stable gain and low saturation voltage at medium currents (−10 mA to −100 mA).

Thermal design must account for R_θJA = 200°C/W in standard TO-92 mounting; derating begins above 25°C at 5.0 mW/°C. Safe operation requires limiting V_CB ≤ −60 V and V_EB ≤ −10 V to prevent junction breakdown, per absolute maximum ratings.

Key Specifications

Pinout & Package

Package: TO-92 (standard through-hole plastic package, 3-pin, lead spacing 0.3 inches). Dimensions conform to JEDEC TO-92 outline; body height ≤ 4.6 mm, lead length ≥ 3.5 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMBT6517 and PN2907A, the MPSA77_D75Z delivers uniquely high gain and low saturation voltage in a through-hole TO-92 package - critical for legacy industrial designs where layout change is prohibitive and base-drive minimization is essential.

Availability

MPSA77_D75Z is available at Aetrix Electronics and suitable for relay drivers, lamp/LED array controls, DC motor direction circuits, and industrial sensor interfaces requiring stable component supply across long-lifecycle manufacturing programs.

Supply support for MPSA77_D75Z 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, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The MPSA77_D75Z belongs to ON Semiconductor's general-purpose bipolar transistor product line, engineered specifically for high-gain, medium-current linear and switching applications in cost-sensitive industrial control systems.

FAQ

What is the maximum continuous collector current rating for the MPSA77_D75Z?

The MPSA77_D75Z has a maximum continuous collector current (I_C) rating of −1.2 A at T_A = 25°C. Derating applies above 25°C at 5.0 mW/°C. This rating supports robust operation in relay and lamp driver applications where sustained current draw reaches 1 A. Always verify thermal margin using R_θJA = 200°C/W and actual board layout conditions for the MPSA77_D75Z.

Does the MPSA77_D75Z have an integrated base resistor?

No, the MPSA77_D75Z does not include an integrated base resistor. It is a bare PNP Darlington transistor requiring external base biasing. This gives designers full control over base current and switching speed but necessitates careful calculation of R_B to ensure saturation while avoiding excessive base drive. The MPSA77_D75Z datasheet specifies V_BE(on) = −2.0 V at I_C = −100 mA for such calculations.

Can the MPSA77_D75Z replace the MPSA70 in existing designs?

Yes, the MPSA77_D75Z can replace the MPSA70 in most applications, as both are PNP Darlington transistors in TO-92 packages with identical pinout (E-B-C). However, the MPSA77_D75Z offers higher h_FE (≥10,000 vs. ≥10,000 for MPSA70 at −10 mA, but MPSA77_D75Z maintains it at −100 mA), lower V_CE(sat), and same −60 V ratings. Verify base drive compatibility and thermal performance under full load for the MPSA77_D75Z.

What is the thermal resistance from junction to ambient for the MPSA77_D75Z?

The MPSA77_D75Z has a junction-to-ambient thermal resistance (R_θJA) of 200°C/W under standard TO-92 mounting on FR-4 PCB with 1-inch² copper pad. This value assumes natural convection and no forced airflow. For reliable operation at I_C > 500 mA, thermal simulation or empirical testing is recommended to confirm junction temperature stays below 150°C for the MPSA77_D75Z.

Is the MPSA77_D75Z suitable for high-frequency switching applications?

No, the MPSA77_D75Z is not suitable for high-frequency switching. Its f_T is 100 MHz, but Darlington architecture introduces significant storage time and slow turn-off characteristics. It is intended for low-frequency applications (<10 kHz), such as relay control, lamp dimming, or DC motor direction switching. For PWM above 20 kHz, consider MOSFET alternatives. The MPSA77_D75Z excels in gain and simplicity-not speed.