onsemi MPSA77_D74Z

Overview

MPSA77_D74Z from ON Semiconductor (formerly Fairchild) is a PNP Darlington transistor optimized for high-current-switching applications with DC current gain ≥10,000 at IC = −100 mA, VCE = −5.0 V, and VCE(sat) = −1.5 V at IC = −100 mA / IB = −0.1 mA. It supports continuous collector current up to −1.2 A and operates across −55 °C to +150 °C junction temperature range, commonly used in relay drivers and low-frequency power switching circuits.

For engineers reviewing the MPSA77_D74Z datasheet, MPSA77_D74Z pinout, MPSA74_D74Z application, or MPSA77_D74Z equivalent, key selection criteria include guaranteed hFE ≥10,000 at 100 mA, TO-92 package thermal resistance RθJA = 200 °C/W, −60 V VCES rating, and verified PNP Darlington topology for high-gain, low-base-drive switching.

Technical Context

The MPSA77_D74Z implements a monolithic PNP Darlington pair with integrated base-emitter resistor network absent - requiring external base bias control. Its structure delivers ultra-high DC current gain while maintaining VBE(on) = −2.0 V at IC = −100 mA, enabling direct interface with TTL/CMOS logic outputs when combined with appropriate base current limiting.

It exhibits fT = 100 MHz under IC = −10 mA, VCE = −5.0 V conditions, confirming suitability for low-speed switching (≤10 kHz) rather than RF amplification. Thermal design must account for PD(max) = 625 mW at 25 °C, derating linearly at 5.0 mW/°C above ambient.

Key Specifications

Pinout & Package

Package: TO-92 - standard through-hole plastic package with 0.1″ lead pitch, compatible with manual soldering and wave soldering processes. Dimensions conform to JEDEC TO-92 outline.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMBT6520 and PN2907A, the MPSA77_D74Z uniquely balances ultra-high gain (≥10,000), TO-92 compatibility, and 1.2 A current capability - making it optimal for cost-sensitive, medium-power switching where base drive is scarce.

Availability

MPSA77_D74Z is available at Aetrix Electronics and suitable for relay drivers, LED array controllers, industrial sensor interfaces, and low-speed DC motor control requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MPSA77_D74Z 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, communications, and computing markets.

The MPSA77_D74Z belongs to ON Semiconductor's legacy bipolar transistor portfolio, designed specifically for high-gain, medium-power linear and switching applications in industrial control and instrumentation.

FAQ

What is the maximum continuous collector current rating for the MPSA77_D74Z?

The MPSA77_D74Z has a maximum continuous collector current (IC) rating of −1.2 A at Ta = 25 °C. Derating applies above ambient temperature: power dissipation drops by 5.0 mW/°C, limiting usable current in elevated-temperature environments. This rating assumes adequate PCB copper area for heat spreading and excludes pulsed operation.

Does the MPSA77_D74Z include an internal base-emitter resistor?

No, the MPSA77_D74Z does not integrate any base-emitter resistor. It is a bare PNP Darlington transistor requiring external base current limiting. Designers must calculate and place a series resistor between the driving source and pin 2 (base) to ensure IB remains within safe limits - typically ≤−0.1 mA for reliable saturation at IC = −100 mA.

What is the typical VCE(sat) value for the MPSA77_D74Z under standard test conditions?

The MPSA77_D74Z specifies VCE(sat) = −1.5 V at IC = −100 mA and IB = −0.1 mA. This value reflects the voltage drop across the device when fully saturated, directly impacting conduction losses in switching applications. Measured at 25 °C, it increases slightly at higher junction temperatures but remains below −1.8 V up to TJ = 125 °C.

Can the MPSA77_D74Z be used as a direct replacement for the MPSA70 in existing designs?

No - the MPSA77_D74Z is a PNP Darlington, whereas the MPSA70 is an NPN general-purpose transistor. Their polarities, gain structures, and saturation behaviors differ fundamentally. Substituting MPSA77_D74Z for MPSA70 would invert circuit functionality and likely cause failure unless the entire biasing and topology are redesigned.

Is the MPSA77_D74Z compliant with RoHS and lead-free soldering standards?

Yes, the MPSA77_D74Z is RoHS-compliant and qualified for lead-free reflow soldering per J-STD-020. Its TO-92 package uses matte tin-plated leads and meets JEDEC moisture sensitivity level (MSL) 1 specifications - allowing unlimited floor life and compatibility with standard 260 °C peak reflow profiles.