onsemi FMBA56

Overview

FMBA56 from Fairchild Semiconductor is a PNP multi-chip general-purpose amplifier optimized for linear amplification and switching at collector currents up to −500 mA, featuring −80 V V_CEO/V_CBO, −4 V V_EBO, 100 minimum h_FE at −10 mA and −100 mA, and 50 MHz f_T; used in DC-coupled audio preamplifier stages and relay driver circuits.

For engineers reviewing the FMBA56 datasheet, pinout, applications, or equivalent options, key selection criteria include verified PNP polarity, SuperSOT-6 package thermal performance (R_θJA = 180°C/W), −0.25 V V_CE(sat) at −100 mA/−10 mA drive, and −1.2 V V_BE(on) under same conditions - all critical for low-loss high-current switching and stable bias design.

Technical Context

The FMBA56 integrates two matched PNP transistors in a single SuperSOT-6 package, sharing common emitter connections per die but with independent base and collector terminals (C1/E1/B1 and C2/E2/B2). It operates as a dual discrete amplifier pair rather than a monolithic IC, supporting parallel or push-pull configurations.

Designed on Fairchild's Process 73, it delivers consistent h_FE ≥ 100 across −10 mA to −100 mA I_C, maintains V_CE(sat) ≤ −0.25 V at β = 10, and sustains operation from −55°C to +150°C junction temperature with 700 mW total dissipation derated at 5.6 mW/°C above 25°C.

Key Specifications

Pinout & Package

FMBA56 uses the SuperSOT-6 (JEDEC MO-193) package: 6-lead, 1.6 mm wide, surface-mount, with pin 1 marked by a dot. Thermal pad is not present; power dissipation relies on leadframe conduction and PCB trace routing.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MBT3906DW1T1G and NSV60601MR6T1G, the FMBA56 uniquely balances −80 V breakdown, −500 mA current capability, dual-transistor integration, and 180°C/W thermal resistance - making it optimal for space-constrained, high-reliability industrial switching where both voltage headroom and channel density matter.

Availability

FMBA56 is available at Aetrix Electronics and suitable for industrial relay drivers, DC-coupled audio preamplifiers, and dual-load power switches requiring stable component supply and long-term lifecycle support.

Supply support for FMBA56 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

Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and discrete components before its acquisition by ON Semiconductor in 2016.

The FMBA56 belongs to Fairchild's SuperSOT-6 discrete transistor family, designed specifically for high-density, high-reliability industrial and automotive switching applications where dual PNP functionality and robust voltage ratings are essential.

FAQ

What is the maximum continuous collector current rating for the FMBA56?

The FMBA56 has a maximum continuous collector current rating of −500 mA per transistor, as specified in its Absolute Maximum Ratings table. This rating applies under TA = 25°C with proper PCB thermal management. Derating is required above 25°C at 5.6 mW/°C, and actual usable current depends on ambient temperature, PCB copper area, and airflow. The FMBA56 is rated for −500 mA per channel, not total device current.

Does the FMBA56 have pin-to-pin compatibility with other SuperSOT-6 PNP transistors?

No documented pin-to-pin compatibility exists between the FMBA56 and other SuperSOT-6 PNP transistors such as the FMB200 or MMDT3906. The FMBA56 features a unique internal connection (C1–E1–B1–C2–E2–B2) confirmed in Figure 2 of its datasheet, differing from standard dual-transistor pinouts. Always verify pin mapping against the official FMBA56 Rev. 1.1.0 datasheet before board reuse.

What is the typical current gain (hFE) of the FMBA56 at low and high collector currents?

The FMBA56 guarantees h_FE ≥ 100 at both −10 mA and −100 mA collector current, with V_CE = −1.0 V and T_A = 25°C. This flat h_FE curve across two decades of current supports stable bias design in both small-signal amplification and medium-power switching. Typical h_FE may exceed 150 at −10 mA but is not guaranteed beyond the minima stated in the Electrical Characteristics table.

Can the FMBA56 be used in push-pull amplifier configurations?

Yes, the FMBA56 can be used in push-pull amplifier configurations as the PNP half of the output stage, especially when paired with an NPN complement such as the FMBA55 or MMDT3904. Its matched h_FE, low V_CE(sat), and dual-transistor layout simplify symmetric drive design. However, ensure emitter degeneration and thermal coupling are implemented to minimize crossover distortion and thermal runaway in Class AB operation.

What is the thermal resistance (RθJA) of the FMBA56, and how does it affect PCB layout?

The FMBA56 has a specified R_θJA of 180°C/W under JEDEC-standard FR-4 PCB conditions (76 × 114 × 1.57 mm with minimum land pattern). This means each watt of dissipated power raises junction temperature by 180°C above ambient. To stay within the 150°C max junction limit at full 700 mW, ambient must remain below ~25°C unless additional copper pour, thermal vias, or airflow is added. Layout must avoid narrow traces on collector/emitter paths to prevent localized heating.