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

onsemi MMBT5551

Name: MMBT5551
Brand: onsemi
SKU: MMBT5551
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MMBT5551

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: MMBT5551.pdf

Description:: TRANS NPN 160V 0.6A SOT-23-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

MMBT5551 from ON Semiconductor is an NPN general-purpose amplifier transistor designed for high-voltage amplification and gas discharge display driver circuits. It features V_CEO = 160 V, I_C = 600 mA, h_FE = 80–250 (at I_C = 10 mA), f_T = 100 MHz, and operates across –55°C to +150°C junction temperature range. Its SOT-23 package supports compact, surface-mount high-voltage switching in industrial control interfaces.

For engineers reviewing the MMBT5551 datasheet, pinout, applications, or equivalent options, key selection criteria include high-voltage breakdown capability, DC current gain consistency at 10 mA bias, thermal resistance (R_θJA = 357°C/W), and suitability for linear amplification or saturated switching in low-to-medium power analog stages.

Technical Context

The MMBT5551 is a silicon NPN bipolar junction transistor optimized for general-purpose amplification with emphasis on high collector-emitter breakdown voltage and stable h_FE over temperature. Its structure supports operation under V_CE up to 160 V while maintaining low V_CE(sat) ≤ 0.20 V at I_C = 50 mA / I_B = 5 mA.

It delivers f_T = 100 MHz at I_C = 10 mA / V_CE = 10 V, enabling use in audio-frequency amplifiers and medium-speed switching. Input capacitance (C_ibo = 20 pF) and output capacitance (C_obo = 6.0 pF) are specified at 1 MHz, supporting predictable AC response in discrete gain stages.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	160 V - Enables safe operation in circuits with up to 160 V collector supply, suitable for CRT display drivers and relay drivers.
I_C (max)	600 mA - Supports continuous collector current up to 600 mA, sufficient for medium-power switching and linear amplification.
h_FE	80–250 - DC current gain range at I_C = 10 mA / V_CE = 5 V ensures reliable biasing in common-emitter amplifier configurations.
f_T	100 MHz - Current gain bandwidth product allows stable small-signal amplification up to ~10 MHz with adequate gain margin.
R_θJA	357°C/W - Thermal resistance reflects SOT-23 package limitations; requires PCB copper area or derating above 25°C ambient.
V_BE(sat)	1.0 V - Base-emitter saturation voltage at I_C = 10 mA / I_B = 1 mA defines minimum drive requirement for hard saturation.
NF	8.0 dB - Noise figure measured at I_C = 250 μA / V_CE = 5 V / R_S = 1 kΩ indicates suitability for low-noise preamplifier front-ends.

Pinout & Package

SOT-23 (TO-236AB) 3-lead surface-mount plastic package with gull-wing leads; marking "3S" on top surface. Standard lead configuration: Pin 1 = Base, Pin 2 = Emitter, Pin 3 = Collector.

Pin/Terminal	Circuit Role	Design Meaning
1 (Base)	Control input terminal	Receives base current to modulate collector current; requires series resistor for current limiting in digital switch applications.
2 (Emitter)	Current return path	Common reference node for emitter-follower or grounded-emitter configurations; connects directly to ground or emitter resistor.
3 (Collector)	Output current terminal	Delivers amplified/saturated output current; must be connected through load to positive supply up to 160 V.

Key Features

Feature	Design Value
High V_CEO rating	160 V enables direct interface with legacy high-voltage logic and display systems without level-shifting circuitry.
Wide h_FE range	80–250 at I_C = 10 mA supports consistent DC bias design across production lots without individual trimming.
Low V_CE(sat)	≤ 0.20 V at I_C = 50 mA minimizes conduction loss in switching applications, improving efficiency in driver stages.
Specified noise figure	8.0 dB at audio frequencies allows use in low-noise preamp stages where discrete transistors outperform integrated op-amps.
SOT-23 footprint	Standard JEDEC TO-236AB package enables automated assembly and space-constrained PCB layouts in industrial modules.

Applications

Gas Discharge Display Driver	High-Voltage Linear Amplifier
Use Scenario: Driving segments of neon or Nixie tube displays requiring 100–150 V anode supplies. IC Role / Device Role / Timing Role: NPN switch operating in saturation mode to sink segment current while blocking high anode voltage. Use Value: V_CEO = 160 V and I_C = 600 mA allow direct connection to display anodes without external HV transistors or transformers.	Use Scenario: Building discrete audio preamplifier stages in test equipment or analog signal conditioning modules. IC Role / Device Role / Timing Role: Common-emitter amplifier configured for mid-band voltage gain with DC-coupled feedback. Use Value: f_T = 100 MHz and NF = 8.0 dB support flat frequency response up to 10 MHz and low-noise signal amplification.
Industrial Relay Driver	Legacy Logic Interface
Use Scenario: Controlling 24–48 V DC relays in PLC I/O modules using microcontroller GPIO outputs. IC Role / Device Role / Timing Role: Switching transistor biased into saturation to energize relay coils with minimal V_CE(sat) loss. Use Value: V_CEO = 160 V provides robust flyback voltage clamping margin during coil de-energization.	Use Scenario: Level translation between 3.3 V/5 V logic and older 12 V TTL or discrete logic families. IC Role / Device Role / Timing Role: Inverter or buffer stage providing current gain and voltage swing extension. Use Value: h_FE ≥ 80 at I_C = 10 mA ensures reliable switching with low-drive microcontrollers and clean logic transitions.

Gas Discharge Display Driver

High-Voltage Linear Amplifier

Use Scenario: Driving segments of neon or Nixie tube displays requiring 100–150 V anode supplies.

IC Role / Device Role / Timing Role: NPN switch operating in saturation mode to sink segment current while blocking high anode voltage.

Use Value: V_CEO = 160 V and I_C = 600 mA allow direct connection to display anodes without external HV transistors or transformers.

Use Scenario: Building discrete audio preamplifier stages in test equipment or analog signal conditioning modules.

IC Role / Device Role / Timing Role: Common-emitter amplifier configured for mid-band voltage gain with DC-coupled feedback.

Use Value: f_T = 100 MHz and NF = 8.0 dB support flat frequency response up to 10 MHz and low-noise signal amplification.

Industrial Relay Driver

Legacy Logic Interface

Use Scenario: Controlling 24–48 V DC relays in PLC I/O modules using microcontroller GPIO outputs.

IC Role / Device Role / Timing Role: Switching transistor biased into saturation to energize relay coils with minimal V_CE(sat) loss.

Use Value: V_CEO = 160 V provides robust flyback voltage clamping margin during coil de-energization.

Use Scenario: Level translation between 3.3 V/5 V logic and older 12 V TTL or discrete logic families.

IC Role / Device Role / Timing Role: Inverter or buffer stage providing current gain and voltage swing extension.

Use Value: h_FE ≥ 80 at I_C = 10 mA ensures reliable switching with low-drive microcontrollers and clean logic transitions.

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; h_FE = 200–450 at I_C = 10 mA; R_θJA = 375°C/W	Not suitable for >60 V applications; better for low-voltage logic buffering and sensor interfaces.	Select when high-voltage capability is unnecessary and tighter h_FE tolerance is required.
MPSA42	Higher V_CEO = 300 V; TO-92 package; PD = 625 mW; f_T = 50 MHz	Through-hole mounting; lower bandwidth but superior HV handling for flyback snubbers and telecom line drivers.	Choose for through-hole prototyping or applications demanding >200 V standoff with relaxed speed requirements.

Compared with BC847B and MPSA42, the MMBT5551 uniquely balances 160 V breakdown, 100 MHz f_T, and SOT-23 mountability-making it optimal for surface-mount high-voltage amplification where TO-92 is impractical and BC847B lacks voltage margin.

Availability

MMBT5551 is available at Aetrix Electronics and suitable for gas discharge display drivers, industrial relay interfaces, high-voltage linear amplifiers, and legacy logic level translators requiring stable component supply and full traceability.

Supply support for MMBT5551 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 (formerly Fairchild Semiconductor) is a global supplier of energy-efficient semiconductor solutions for automotive, industrial, cloud computing, and consumer electronics.

The MMBT5551 belongs to ON Semiconductor's general-purpose bipolar transistor product line, engineered for reliability in high-voltage analog and switching applications where discrete transistor performance and proven ruggedness are critical.

FAQ

What is the maximum collector-emitter voltage rating for the MMBT5551?

The MMBT5551 has a guaranteed V_CEO rating of 160 V at I_C = 1.0 mA and T_A = 25°C. This rating is validated per JEDEC standards and applies to continuous DC operation. Exceeding this voltage risks avalanche breakdown and permanent device damage. The MMBT5551 is therefore appropriate for circuits with supply rails up to 160 V, such as Nixie tube drivers and industrial control outputs.

Does the MMBT5551 have a specified noise figure, and under what conditions?

Yes, the MMBT5551 has a specified noise figure of 8.0 dB, measured at I_C = 250 μA, V_CE = 5.0 V, R_S = 1.0 kΩ, and frequency range 10 Hz to 15.7 kHz. This value is documented in the official ON Semiconductor datasheet Rev. 1.1.0 and reflects its suitability for low-noise preamplifier applications where discrete transistor noise performance is critical.

What is the pin configuration of the MMBT5551 in its SOT-23 package?

The MMBT5551 uses standard SOT-23 pinout: Pin 1 is Base, Pin 2 is Emitter, Pin 3 is Collector. This configuration is confirmed in Figure 12 of the ON Semiconductor datasheet and matches JEDEC TO-236AB specification. The top marking "3S" aligns with this orientation when viewed with the marking side up and leads pointing downward.

How does the thermal performance of the MMBT5551 compare to the through-hole 2N5551?

The MMBT5551 has R_θJA = 357°C/W versus 200°C/W for the 2N5551 in TO-92, reflecting higher thermal resistance due to its smaller SOT-23 package. Its power dissipation is rated at 350 mW (vs. 625 mW for 2N5551), with derating of 2.8 mW/°C above 25°C. Designers must provide adequate PCB copper area or reduce ambient temperature to maintain T_J ≤ 150°C in sustained operation.

Is the MMBT5551 suitable for switching applications, and what is its typical V_CE(sat)?

Yes, the MMBT5551 is widely used in saturated switching applications. Its V_CE(sat) is specified as ≤ 0.15 V at I_C = 10 mA / I_B = 1.0 mA and ≤ 0.20 V at I_C = 50 mA / I_B = 5.0 mA. These values confirm efficient on-state conduction, making the MMBT5551 effective in relay drivers, LED matrix controllers, and other medium-current digital output stages.

MMBT5551 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):: 160 V

Vce Saturation (Max) @ Ib, Ic:: 200mV @ 5mA, 50mA

Current - Collector Cutoff (Max):: 50nA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 80 @ 10mA, 5V

Power - Max:: 350 mW

Frequency - Transition:: 100MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-3

MMBT5551 FAQ

1.How can I place an order for MMBT5551 through Aetrix?

Please submit a Request for Quotation (RFQ) for MMBT5551 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 MMBT5551 reliable?

The price and inventory of MMBT5551 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MMBT5551 is usually 5 days.

3.What payment methods are accepted for MMBT5551?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MMBT5551 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MMBT5551?

MMBT5551 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MMBT5551 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 MMBT5551?

For technical support, including MMBT5551 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MMBT5551 requirements.

6.How does Aetrix verify that MMBT5551 is sourced from the original manufacturer or authorized distributors?

All MMBT5551 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 MMBT5551 meets industry standards.

7.What is the process for return or replacement of MMBT5551?

All MMBT5551 units undergo pre-shipment inspection (PSI). If there is an issue with MMBT5551, 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 MMBT5551 part is unused and in its original packaging.

Return procedure for MMBT5551:

1.Submit a request within 90 days.

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

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