onsemi MMBT5089

Overview

MMBT5089 from ON Semiconductor is an NPN general-purpose amplifier optimized for low-noise, high-gain signal amplification at collector currents from 1 µA to 50 mA. It features V_CEO = 25 V, h_FE = 400–1200 (at I_C = 10 mA), f_T = 50 MHz, NF = 2.0 dB (at I_C = 100 µA), and is packaged in SOT-23 for space-constrained analog front-ends in sensor interfaces and audio preamps.

For engineers reviewing the MMBT5089 datasheet, pinout, applications, or equivalent options, key selection considerations include its low-noise performance at microamp bias, high DC gain stability across temperature, SOT-23 thermal resistance (R_θJA = 357 °C/W), and compatibility with low-voltage, low-power analog signal chains requiring precision small-signal amplification.

Technical Context

The MMBT5089 operates as a discrete NPN bipolar junction transistor with fixed-emitter bias topology, supporting linear amplification in common-emitter configuration. Its design emphasizes noise minimization via optimized base doping and epitaxial structure, enabling stable h_FE > 400 at I_C = 1.0 mA and V_CE = 5.0 V.

It delivers f_T = 50 MHz under 500 µA/5.0 V conditions and maintains C_cb = 4.0 pF and C_eb = 10 pF at specified reverse biases - parameters critical for RF-coupled preamplifier stages and wideband instrumentation front-ends up to 10 MHz.

Key Specifications

Pinout & Package

SOT-23 plastic surface-mount package with gull-wing leads; marked "1Q" or "1R" per ON Semiconductor standard marking code for MMBT5089.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN general-purpose amplifier applications.

Compared with MMBT5088 and BC847B, the MMBT5089 uniquely balances ultra-low noise (2.0 dB), high gain (up to 1200), and 25 V operation - making it the preferred choice for precision, low-power analog signal chains where SNR and bias stability are prioritized over raw speed or voltage headroom.

Availability

MMBT5089 is available at Aetrix Electronics and suitable for audio preamplifier stages, temperature sensor signal conditioning, and low-power analog front-ends requiring stable component supply, long-term lifecycle assurance, and traceable sourcing for production programs.

Supply support for MMBT5089 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 (now onsemi) is a global semiconductor manufacturer specializing in energy-efficient power management, analog, and sensor solutions for automotive, industrial, and cloud infrastructure markets.

The MMBT5089 belongs to onsemi's general-purpose bipolar transistor family designed specifically for low-noise, high-gain amplification in battery-powered and precision analog systems - emphasizing manufacturability, thermal reliability, and parameter consistency across temperature.

FAQ

What is the maximum collector-emitter voltage rating for the MMBT5089?

The MMBT5089 has a maximum collector-emitter voltage (V_CEO) rating of 25 V at T_A = 25°C. This rating is absolute - exceeding it risks avalanche breakdown and permanent device failure. Derating is required above 25°C ambient; consult the datasheet's thermal curves for safe operation at elevated temperatures. The MMBT5089 must not be used in circuits where V_CE could transiently exceed 25 V without clamping.

Does the MMBT5089 support low-current biasing for micropower designs?

Yes, the MMBT5089 is explicitly characterized down to I_C = 1 µA, with h_FE ≥ 300 at I_C = 100 µA and V_CE = 5.0 V. Its low noise figure (2.0 dB) and stable gain at microamp bias make it suitable for micropower sensor interfaces and battery-operated analog front-ends. The MMBT5089 achieves usable gain and bandwidth even at I_C = 10 µA, unlike many general-purpose transistors that degrade significantly below 100 µA.

What is the thermal resistance of the MMBT5089 in its SOT-23 package?

The MMBT5089 in SOT-23 has a junction-to-ambient thermal resistance (R_θJA) of 357 °C/W when mounted on a standard FR-4 PCB (1.6" × 1.6" × 0.06"). This value assumes no copper pour or thermal vias. For reliable operation above 100 mW dissipation, PCB layout must include thermal relief - such as extended copper pads or thermal vias - to reduce effective R_θJA. The MMBT5089's R_θJC is not specified, as the SOT-23 package lacks a thermal pad.

How does the noise performance of the MMBT5089 compare to other SOT-23 NPN transistors?

The MMBT5089 delivers industry-leading noise performance among general-purpose SOT-23 NPN transistors, with a noise figure of 2.0 dB at I_C = 100 µA, V_CE = 5.0 V, R_S = 10 kΩ, and 10 Hz–15.7 kHz bandwidth. This is 2–3 dB lower than typical alternatives like BC847B (≈4.5 dB) and significantly better than MMBT3904 (≈5 dB). The MMBT5089's low-noise advantage is most pronounced at sub-milliamp bias points, where its optimized epitaxial structure suppresses flicker noise.

Is the MMBT5089 pin-compatible with the MMBT5088?

Yes, the MMBT5089 and MMBT5088 share identical SOT-23 packaging, pinout (Emitter-Base-Collector on pins 1-2-3), and marking convention ("1Q" vs "1R"). They are mechanically and electrically interchangeable at the board level. However, the MMBT5089 has lower V_CEO (25 V vs 30 V) and higher minimum h_FE at I_C = 10 mA (400 vs 300), so substitution requires verification of voltage margin and gain requirements in the target circuit. The MMBT5089 is not a drop-in replacement if the design relies on 30 V breakdown tolerance.