onsemi MMBT6428LT1

Overview

MMBT6428LT1 from onsemi is an NPN silicon small-signal amplifier transistor in SOT-23 package, rated for 50 V_CEO, 200 mA continuous collector current, and 100–700 MHz f_T, optimized for low-noise RF and general-purpose amplification in portable audio and wireless receiver front-ends.

For engineers reviewing the MMBT6428LT1 datasheet, pinout, applications, or equivalent options, key selection criteria include its 50 V breakdown rating, 250–1250 h_FE range across operating currents, 0.2–0.6 V_CE(sat) at 10–100 mA, 3.0 pF C_obo, and SOT-23 thermal performance (R_JA = 556°C/W on FR-5).

Technical Context

This device operates as a discrete NPN bipolar junction transistor with fixed-emitter bias configuration, supporting linear amplification up to V_CE = 5 V and I_C ≤ 100 mA. Its noise voltage (e_n) ranges from 3.0 nV/√Hz at 1 kHz to 7.0 nV/√Hz at 100 kHz under 1.0 mA I_C, and it exhibits stable h_FE over −55°C to +125°C.

The MMBT6428LT1 delivers high-frequency gain with f_T ≥ 100 MHz at I_C = 1.0 mA and V_CE = 5 V, while maintaining low output capacitance (C_obo ≤ 3.0 pF) and input capacitance (C_ibo ≤ 8.0 pF), enabling use in VHF band amplifiers and broadband preamplifier stages.

Key Specifications

Pinout & Package

SOT-23 (TO-236) plastic surface-mount package, Case 318, Style 6, with 3-pin configuration and JEDEC-standard footprint (2.80 × 1.20 × 0.95 mm). Pin 1 = Base, Pin 2 = Emitter, Pin 3 = Collector.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN small-signal amplifier applications.

Compared with MMBT3904LT1G and BC846B,215, the MMBT6428LT1 offers superior combination of 50 V rating, 100+ MHz f_T, and characterized low-noise performance-making it the preferred choice for VHF amplification and precision analog front-ends where both voltage headroom and signal fidelity matter.

Availability

MMBT6428LT1 is available at Aetrix Electronics and suitable for FM radio IF amplifiers, portable audio preamps, RF detector bias stages, and LED driver switches requiring stable component supply and RoHS-compliant SOT-23 packaging.

Supply support for MMBT6428LT1 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier focused on energy-efficient electronics, delivering power management, analog, sensor, and connectivity solutions.

The MMBT6428LT1 belongs to onsemi's general-purpose bipolar transistor family, engineered for low-noise amplification and reliable switching in consumer, industrial, and communications equipment where SOT-23 footprint and performance consistency are critical.

FAQ

What is the maximum collector-emitter voltage rating for the MMBT6428LT1?

The MMBT6428LT1 has a maximum collector-emitter voltage (V_CEO) rating of 50 Vdc, verified per the official onsemi datasheet (Rev. 3, March 2005). This rating applies at I_C = 1.0 mAdc and I_B = 0, and defines the absolute upper limit before breakdown occurs. Exceeding this voltage risks permanent device damage, even momentarily. The MMBT6428LT1 is therefore suited for circuits with supply rails up to 45 V, preserving 10% safety margin.

Does the MMBT6428LT1 have Pb-free packaging?

Yes, the MMBT6428LT1 is offered in a Pb-free SOT-23 package compliant with RoHS Directive 2011/65/EU. The "G" suffix variant (MMBT6428LT1G) explicitly denotes Pb-free construction, but the base MMBT6428LT1 also meets Pb-free requirements per onsemi's packaging documentation. Both versions share identical electrical specifications and thermal characteristics, and are compatible with standard lead-free reflow profiles per J-STD-020.

What is the typical current-gain bandwidth product (f_T) of the MMBT6428LT1?

The MMBT6428LT1 has a specified f_T range of 100–700 MHz, measured at I_C = 1.0 mAdc, V_CE = 5.0 Vdc, and f = 100 MHz. This wide span reflects process variation across production lots; design should target ≥100 MHz minimum for guaranteed functionality. The upper bound (700 MHz) supports high-fidelity RF amplification, while the lower bound remains sufficient for VHF applications such as FM IF stages and 2.4 GHz PA driver pre-stages.

How is the pinout configured for the MMBT6428LT1 in SOT-23?

The MMBT6428LT1 uses standard SOT-23 pinout: Pin 1 = Base, Pin 2 = Emitter, Pin 3 = Collector. This is confirmed by the official marking diagram and package outline (Case 318, Style 6) in the onsemi datasheet. When viewing the device top-side with the marking visible and the tab facing away, pins are numbered left-to-right as 1–2–3. Correct orientation is essential for bias network placement and thermal pad routing in PCB layout.

What is the thermal resistance (R_JA) of the MMBT6428LT1 on FR-5 board?

The MMBT6428LT1 has a junction-to-ambient thermal resistance (R_JA) of 556°C/W when mounted on a standard FR-5 PCB (1.0 × 0.75 × 0.062 in.) at T_A = 25°C. This value assumes no copper pour or thermal vias. Derating is 1.8 mW/°C above 25°C, meaning maximum power dissipation drops to 216 mW at 30°C ambient. For sustained operation above 100 mW, thermal relief traces or local copper area are recommended to reduce effective R_JA.