onsemi MMBTA14

Overview

MMBTA14 from ON Semiconductor is an NPN silicon Darlington amplifier in SOT-23 package, rated for 30 V_CE, 300 mA continuous collector current, and DC current gain (h_FE) of 10,000–20,000 at I_C = 100 mA, used in low-power switching and signal amplification circuits such as relay drivers and sensor interface stages.

For engineers reviewing the MMBTA14 datasheet, pinout, applications, or equivalent options, this page delivers verified electrical parameters, thermal derating behavior, noise performance at 10–15.7 kHz bandwidth, and SOT-23 footprint compatibility for surface-mount design validation.

Technical Context

The MMBTA14 operates as a two-stage monolithic Darlington pair with base-emitter on voltage up to 2.0 V and collector-emitter saturation voltage ≤1.5 V at I_C = 100 mA / I_B = 0.1 mA. Its f_T of 125 MHz supports high-frequency small-signal amplification under 10 mA bias.

Thermal performance is defined for FR-5 board (R_θJA = 556 °C/W) and alumina substrate (R_θJA = 417 °C/W), with junction temperature range –55°C to +150°C and 2.4 mW/°C derating above 25°C on ceramic.

Key Specifications

Pinout & Package

SOT-23 (TO-236AB) plastic surface-mount package, 3-pin, JEDEC-standard footprint (2.0 × 0.95 × 0.9 mm), moisture sensitivity level 1, rated for reflow up to 260°C for 10 seconds.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMBTA13LT1 and ZTX851, the MMBTA14 offers the highest DC gain in SOT-23 format, enabling ultra-low base current drive and superior noise performance-critical for space-constrained, low-power analog and switching designs where thermal management and footprint size are limiting factors.

Availability

MMBTA14 is available at Aetrix Electronics and suitable for relay driver circuits, low-voltage sensor interfaces, LED current regulation, and industrial logic-level translation requiring stable component supply and consistent parametric performance across production lots.

Supply support for MMBTA14 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 manufacturer specializing in energy-efficient power management, analog, and discrete devices for automotive, industrial, and consumer applications.

The MMBTA14 belongs to ON Semiconductor's general-purpose bipolar transistor family designed for cost-sensitive, high-reliability SMT switching and amplification in industrial controls and instrumentation.

FAQ

What is the maximum collector-emitter voltage rating for the MMBTA14?

The MMBTA14 has a guaranteed minimum collector-emitter breakdown voltage V(BR)_CES of 30 Vdc at I_C = 100 µAdc with base open. This defines its absolute maximum operating voltage in common-emitter configurations. Exceeding 30 V risks avalanche breakdown and permanent damage. The MMBTA14 must be used within this limit in all designs, including transient conditions.

Does the MMBTA14 require an external base resistor in switching applications?

Yes-the MMBTA14 requires an external base resistor to limit base current and ensure reliable saturation. With h_FE ≥10,000, a 100 mA collector load needs only ~10 µA base drive, but typical designs use 0.1–1 mA base current for margin. The MMBTA14 datasheet specifies V_CE(sat) ≤1.5 V at I_C/I_B = 1000, so resistor selection must enforce that ratio.

Can the MMBTA14 be used in linear amplifier configurations?

Yes-the MMBTA14 supports linear operation with verified small-signal characteristics: f_T = 125 MHz, |h_fe| >100 at 100 MHz, and low wideband noise voltage (<2 nV/√Hz). However, its Darlington structure introduces higher V_BE (~2.0 V) and reduced linearity versus single transistors. For MMBTA14 linear use, bias stability and thermal drift must be managed via emitter degeneration.

What is the thermal resistance of the MMBTA14 on a standard FR-5 PCB?

The MMBTA14 exhibits R_θJA = 556 °C/W when mounted on a 1.0 × 0.75 × 0.062 inch FR-5 board per datasheet condition. This yields a maximum power dissipation of 225 mW at 25°C ambient. Derating is 1.8 mW/°C above 25°C, meaning usable power drops to 135 mW at 85°C ambient. The MMBTA14 thermal response curve (Figure 12) confirms single-pulse capability up to 1 W for <1 ms.

Is the MMBTA14 pin-compatible with other SOT-23 transistors like the 2N3904?

No-the MMBTA14 uses the standard SOT-23 pinout (1=Base, 2=Emitter, 3=Collector), but it is not functionally or electrically interchangeable with 2N3904 due to fundamental differences: the MMBTA14 is a Darlington pair with h_FE >10,000 and V_BE ≈2.0 V, whereas the 2N3904 is a single NPN with h_FE ≈100–300 and V_BE ≈0.65 V. Substituting MMBTA14 for 2N3904 will cause severe overbias and potential failure.