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Home > Products > Discrete Semiconductor Products > Transistors > Bipolar (BJT) > Single Bipolar Transistors

onsemi MMBT5550

Name: MMBT5550
Brand: onsemi
SKU: MMBT5550
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MMBT5550

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-236-3, SC-59, SOT-23-3

Datasheet:: MMBT5550.pdf

Description:: TRANS NPN 140V 0.6A SOT-23-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

MMBT5550 from Fairchild Semiconductor is an NPN general-purpose amplifier transistor rated for 140 V V_CEO, 600 mA continuous collector current, and 50 MHz f_T, designed for high-voltage amplification and gas discharge display drivers in industrial control and instrumentation circuits.

For engineers reviewing the MMBT5550 datasheet, pinout, applications, or equivalent options, key selection considerations include its 160 V V_CBO, SOT-23 package with confirmed 1–2–3 base–emitter–collector pinout, thermal resistance of 357 °C/W, and verified h_FE range of 60–250 at IC = 1–50 mA.

Technical Context

The MMBT5550 operates as a discrete NPN bipolar junction transistor optimized for linear amplification and switching in medium-power, high-voltage applications. Its 140 V V_CEO rating and 160 V V_CBO support operation in flyback snubbers and display driver stages where transient voltage margin is critical.

It delivers DC current gain (h_FE) from 60 to 250 across 1–50 mA collector current, with V_CE(sat) ≤ 0.25 V at IC = 50 mA/IB = 5 mA and f_T = 50 MHz under standard test conditions (IC = 10 mA, V_CE = 10 V, f = 100 MHz), confirming suitability for audio preamplifier and pulse amplification roles.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	140 V - supports operation in high-side switch and HV amplifier stages up to 140 V collector-emitter potential
V_CBO	160 V - enables robust collector-base standoff in inductive load switching and snubber networks
I_C (continuous)	600 mA - sufficient for driving gas discharge displays and medium-current signal amplification
f_T	50 MHz - confirms usable bandwidth for audio-frequency amplification and fast-switching applications
P_D (T_A = 25°C)	350 mW - defines maximum steady-state power dissipation on FR-4 PCB without heatsinking
R_θJA	357 °C/W - quantifies thermal bottleneck from junction to ambient on standard 1.6" × 1.6" PCB
h_FE	60–250 - wide DC gain range allows flexible bias design across low- and medium-current operating points

Pinout & Package

MMBT5550 is housed in a surface-mount SOT-23 package with standardized 3-pin configuration and top-marking "1F".

Pin/Terminal	Circuit Role	Design Meaning
1	Base	Control terminal for forward-biased B-E junction; requires ~1.0–1.2 V V_BE(sat) to drive 10–50 mA I_C
2	Emitter	Current return path; grounded or referenced in common-emitter configurations
3	Collector	High-voltage output node; handles up to 140 V and 600 mA with defined saturation behavior

Key Features

Feature	Design Value
High-voltage capability	140 V V_CEO and 160 V V_CBO enable use in HV analog stages and display drivers without external clamping
Wide DC current gain range	h_FE = 60–250 across 1–50 mA ensures stable biasing in both small-signal and medium-power amplification
Low saturation voltage	V_CE(sat) ≤ 0.25 V at 50 mA reduces conduction loss in switching applications
Thermally characterized package	R_θJA = 357 °C/W specified on standard FR-4 PCB aids thermal design for unheatsinked layouts

Applications

Gas Discharge Display Driver	High-Voltage Amplifier Stage
Use Scenario: Driving neon or Nixie tube segments requiring 90–140 V anode voltage and 1–5 mA segment current. IC Role / Device Role / Timing Role: NPN switch controlling current flow through display segment via common-cathode topology. Use Value: 140 V V_CEO and 600 mA I_C allow direct segment drive without series resistors or external HV transistors.	Use Scenario: Linear amplification of sensor signals in industrial process controllers operating up to 120 V supply rails. IC Role / Device Role / Timing Role: Single-stage common-emitter amplifier with emitter degeneration for DC-coupled gain stability. Use Value: 50 MHz f_T and h_FE ≥ 60 at 1 mA ensure adequate bandwidth and gain for 20 kHz analog signal paths.
Inductive Load Snubber Switch	Audio Preamp Input Stage
Use Scenario: Clamping flyback voltage spikes from relay coils or solenoids in PLC I/O modules. IC Role / Device Role / Timing Role: Fast-turn-off NPN clamp transistor absorbing inductive energy during de-energization. Use Value: 160 V V_CBO and low C_obo (6.0 pF) minimize capacitive coupling and improve transient response.	Use Scenario: Low-noise voltage amplification of piezoelectric or microphone signals in portable test equipment. IC Role / Device Role / Timing Role: Common-emitter preamplifier biased at 1–10 mA for optimal noise/gain tradeoff. Use Value: Verified h_FE ≥ 60 at I_C = 1 mA and low V_BE(sat) (1.0 V) simplify bias network design and reduce offset drift.

Gas Discharge Display Driver

High-Voltage Amplifier Stage

Use Scenario: Driving neon or Nixie tube segments requiring 90–140 V anode voltage and 1–5 mA segment current.

IC Role / Device Role / Timing Role: NPN switch controlling current flow through display segment via common-cathode topology.

Use Value: 140 V V_CEO and 600 mA I_C allow direct segment drive without series resistors or external HV transistors.

Use Scenario: Linear amplification of sensor signals in industrial process controllers operating up to 120 V supply rails.

IC Role / Device Role / Timing Role: Single-stage common-emitter amplifier with emitter degeneration for DC-coupled gain stability.

Use Value: 50 MHz f_T and h_FE ≥ 60 at 1 mA ensure adequate bandwidth and gain for 20 kHz analog signal paths.

Inductive Load Snubber Switch

Audio Preamp Input Stage

Use Scenario: Clamping flyback voltage spikes from relay coils or solenoids in PLC I/O modules.

IC Role / Device Role / Timing Role: Fast-turn-off NPN clamp transistor absorbing inductive energy during de-energization.

Use Value: 160 V V_CBO and low C_obo (6.0 pF) minimize capacitive coupling and improve transient response.

Use Scenario: Low-noise voltage amplification of piezoelectric or microphone signals in portable test equipment.

IC Role / Device Role / Timing Role: Common-emitter preamplifier biased at 1–10 mA for optimal noise/gain tradeoff.

Use Value: Verified h_FE ≥ 60 at I_C = 1 mA and low V_BE(sat) (1.0 V) simplify bias network design and reduce offset drift.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BC847B	Lower V_CEO (45 V), higher h_FE (200–450), same SOT-23 package	Not suitable for >60 V applications; preferred for low-voltage, high-gain signal amplification	Select BC847B only when supply voltage remains below 45 V and gain consistency at low I_C is prioritized
MPSA42	Higher V_CEO (300 V), TO-92 package, lower f_T (50 MHz typical but not guaranteed)	Requires through-hole layout; better for ultra-high-voltage switching but less suited for compact SMT designs	Choose MPSA42 only when >200 V standoff is required and board space permits TO-92 mounting

Compared with BC847B and MPSA42, the MMBT5550 uniquely balances 140 V high-voltage capability, SOT-23 surface-mount compatibility, and verified 50 MHz f_T, making it the optimal choice for space-constrained industrial display and HV amplifier designs where both voltage margin and frequency response matter.

Availability

MMBT5550 is available at Aetrix Electronics and suitable for gas discharge display drivers, high-voltage amplifier stages, inductive load snubber switches, and audio preamp input stages requiring stable component supply and long-term industrial availability.

Supply support for MMBT5550 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 MMBT5550 belongs to Fairchild's general-purpose bipolar transistor product line, engineered for reliable high-voltage amplification and switching in industrial and instrumentation applications.

FAQ

What is the maximum collector-emitter voltage rating for the MMBT5550?

The MMBT5550 has a maximum collector-emitter voltage (V_CEO) rating of 140 V at T_A = 25°C. This rating is defined with I_C = 1.0 mA and I_B = 0, and reflects the device's ability to block voltage in common-emitter configuration without breakdown. Operation above this value risks permanent damage, and derating is required at elevated temperatures per the datasheet's absolute maximum ratings table.

What package type and pinout does the MMBT5550 use?

The MMBT5550 uses the SOT-23 surface-mount package with standardized pinout: Pin 1 is Base, Pin 2 is Emitter, and Pin 3 is Collector. The device is marked "1F" on the top surface. This pin assignment is confirmed in the mechanical drawings and ordering information section of the Fairchild MMBT5550 Rev. A datasheet.

Does the MMBT5550 have a specified current gain bandwidth product (f_T)?

Yes, the MMBT5550 has a specified current gain bandwidth product (f_T) of 50 MHz, measured at I_C = 10 mA, V_CE = 10 V, and f = 100 MHz. This parameter is listed in the Small Signal Characteristics table and confirms the device's suitability for audio-frequency amplification and moderate-speed switching applications.

What is the thermal resistance (R_θJA) of the MMBT5550 under standard mounting conditions?

The MMBT5550 has a junction-to-ambient thermal resistance (R_θJA) of 357 °C/W when mounted on a standard FR-4 PCB measuring 1.6" × 1.6" × 0.06". This value is specified in the Thermal Characteristics section and is essential for calculating maximum allowable power dissipation at elevated ambient temperatures.

Can the MMBT5550 be used in gas discharge display driver circuits?

Yes, the MMBT5550 is explicitly designed for gas discharge display drivers, as stated in its product title and application description. Its 140 V V_CEO, 600 mA I_C, and low V_CE(sat) make it suitable for directly switching neon or Nixie tube segments powered from 90–140 V supplies while maintaining reliable turn-on and thermal performance.

MMBT5550 Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-236-3, SC-59, SOT-23-3

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 600 mA

Voltage - Collector Emitter Breakdown (Max):: 140 V

Vce Saturation (Max) @ Ib, Ic:: 250mV @ 5mA, 50mA

Current - Collector Cutoff (Max):: 100nA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 60 @ 10mA, 5V

Power - Max:: 350 mW

Frequency - Transition:: 50MHz

Operating Temperature:: -55°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-3

MMBT5550 FAQ

1.How can I place an order for MMBT5550 through Aetrix?

Please submit a Request for Quotation (RFQ) for MMBT5550 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for MMBT5550 reliable?

The price and inventory of MMBT5550 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MMBT5550 is usually 5 days.

3.What payment methods are accepted for MMBT5550?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MMBT5550 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MMBT5550?

MMBT5550 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MMBT5550 order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for MMBT5550?

For technical support, including MMBT5550 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MMBT5550 requirements.

6.How does Aetrix verify that MMBT5550 is sourced from the original manufacturer or authorized distributors?

All MMBT5550 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that MMBT5550 meets industry standards.

7.What is the process for return or replacement of MMBT5550?

All MMBT5550 units undergo pre-shipment inspection (PSI). If there is an issue with MMBT5550, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The MMBT5550 part is unused and in its original packaging.

Return procedure for MMBT5550:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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