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

onsemi 2N5551ZL1

Name: 2N5551ZL1
Brand: onsemi
SKU: 2N5551ZL1
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 2N5551ZL1

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-226-3, TO-92-3 Long Body, Formed Leads

Datasheet:: 2N5551ZL1.pdf

Description:: TRANS NPN 160V 0.6A TO92

Quantity:: RFQ Add To RFQ list

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Inventory:6,387

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Product details

Overview

2N5551ZL1 from onsemi is an NPN silicon general-purpose amplifier transistor in TO-92 package, rated for 160 V_CEO, 600 mA continuous collector current, and 625 mW power dissipation at 25°C ambient. It delivers DC current gain (h_FE) of 80–250 at I_C = 1.0–50 mA and supports high-frequency amplification up to 300 MHz f_T, commonly used in audio preamplifier stages and switching regulators.

For engineers reviewing the 2N5551ZL1 datasheet, pinout, applications, or equivalent options, key selection considerations include its 160 V_CEO rating, 300 MHz transition frequency, low noise figure (8.0 dB), TO-92 mechanical compatibility, and Pb-free packaging compliance per onsemi's RoHS strategy.

Technical Context

The 2N5551ZL1 operates as a medium-voltage, medium-current NPN bipolar junction transistor optimized for linear amplification and fast-switching applications. Its 180 V_CBO and 160 V_CEO ratings support operation in higher-voltage analog front-ends, while its 300 MHz f_T enables RF amplifier use up to VHF band.

Thermal design is constrained by R_JA = 200°C/W and R_JC = 83.3°C/W, requiring careful PCB copper area planning for sustained 600 mA operation. The device exhibits h_FE variation across temperature (−55°C to +150°C) and collector current, with saturation voltages V_CE(sat) ≤ 0.25 V and V_BE(sat) ≤ 1.2 V under specified drive conditions.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	160 Vdc - Supports amplifier or switch operation up to 160 V collector-emitter voltage without breakdown.
I_C (max)	600 mAdc - Enables driving moderate loads such as relay coils or small-signal power stages.
P_D @ T_A = 25°C	625 mW - Limits continuous power handling in ambient-air convection cooling; derates 5.0 mW/°C above 25°C.
f_T	100–300 MHz - Validates suitability for VHF amplifiers, oscillator buffers, and broadband signal conditioning.
h_FE	80–250 - Provides stable current amplification across 1–50 mA collector current range for bias-critical circuits.
NF	8.0 dB @ I_C = 250 μA - Confirms low-noise performance in sensitive preamplifier inputs.
C_ibo	20 pF - Defines input capacitance affecting high-frequency stability and bandwidth in common-emitter configurations.

Pinout & Package

2N5551ZL1 uses the standard TO-92 (Case 29, Style 1) plastic package with 3-pin vertical lead configuration and Pb-free finish. Leads are internally formed for through-hole mounting, with defined mechanical dimensions per ON Semiconductor CASE 29-11 specification.

Pin/Terminal	Circuit Role	Design Meaning
1	Emitter	Current sink terminal; connects to ground or emitter resistor in common-emitter amplifier; polarity defines NPN operation.
2	Base	Control electrode; requires ~1.0–1.2 V forward bias to saturate; drives current proportional to h_FE × I_B.
3	Collector	Current source terminal; connects to supply rail or load; withstands up to 160 V relative to emitter in active mode.

Key Features

Feature	Design Value
High V_CEO rating	160 V - Allows direct replacement of lower-voltage transistors in legacy 120 V line-powered circuits without redesign.
Low noise figure	8.0 dB - Reduces signal degradation in microphone preamps and sensor interface amplifiers where SNR is critical.
Wide h_FE range	80–250 - Accommodates production spread while maintaining functional gain in fixed-bias designs.
Pb-free TO-92 package	RoHS-compliant finish - Meets global environmental regulations without requiring lead-free solder process requalification.
High f_T	300 MHz - Enables stable gain in 50–100 MHz RF amplifier stages without external neutralization.

Applications

Audio Preamplifier Stage	Switching Regulator Driver
Use Scenario: Low-noise voltage amplification of electret microphone output before ADC sampling in portable voice recorders. IC Role / Device Role / Timing Role: NPN small-signal amplifier in common-emitter configuration with emitter degeneration. Use Value: 8.0 dB noise figure and 200 h_fe at 1 mA ensure >65 dB SNR in 20 Hz–20 kHz band without active filtering.	Use Scenario: Driving gate of a power MOSFET in 48 V input buck converter operating at 250 kHz switching frequency. IC Role / Device Role / Timing Role: Fast-switching BJT buffer stage providing current gain between PWM controller and MOSFET gate. Use Value: 300 MHz f_T and 0.25 V V_CE(sat) enable full turn-on within <100 ns, minimizing switching losses.
High-Voltage Analog Front-End	Industrial Sensor Interface
Use Scenario: Signal conditioning for 100 V-range industrial thermocouple amplifiers requiring isolation and level shifting. IC Role / Device Role / Timing Role: Level-shifting emitter follower with 160 V_CEO headroom to handle transient overvoltage events. Use Value: 180 V_CBO and −55°C to +150°C operating range ensure reliability in unregulated factory environments.	Use Scenario: Amplifying millivolt-level outputs from strain-gauge bridges in load-cell instrumentation. IC Role / Device Role / Timing Role: Differential pair input stage in precision instrumentation amplifier topology. Use Value: Tight h_FE matching across batches and low C_ibo (20 pF) preserve common-mode rejection at 1 kHz.

Audio Preamplifier Stage

Switching Regulator Driver

Use Scenario: Low-noise voltage amplification of electret microphone output before ADC sampling in portable voice recorders.

IC Role / Device Role / Timing Role: NPN small-signal amplifier in common-emitter configuration with emitter degeneration.

Use Value: 8.0 dB noise figure and 200 h_fe at 1 mA ensure >65 dB SNR in 20 Hz–20 kHz band without active filtering.

Use Scenario: Driving gate of a power MOSFET in 48 V input buck converter operating at 250 kHz switching frequency.

IC Role / Device Role / Timing Role: Fast-switching BJT buffer stage providing current gain between PWM controller and MOSFET gate.

Use Value: 300 MHz f_T and 0.25 V V_CE(sat) enable full turn-on within <100 ns, minimizing switching losses.

High-Voltage Analog Front-End

Industrial Sensor Interface

Use Scenario: Signal conditioning for 100 V-range industrial thermocouple amplifiers requiring isolation and level shifting.

IC Role / Device Role / Timing Role: Level-shifting emitter follower with 160 V_CEO headroom to handle transient overvoltage events.

Use Value: 180 V_CBO and −55°C to +150°C operating range ensure reliability in unregulated factory environments.

Use Scenario: Amplifying millivolt-level outputs from strain-gauge bridges in load-cell instrumentation.

IC Role / Device Role / Timing Role: Differential pair input stage in precision instrumentation amplifier topology.

Use Value: Tight h_FE matching across batches and low C_ibo (20 pF) preserve common-mode rejection at 1 kHz.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
2N5551G	Pb-free TO-92 variant with identical electrical specs and marking; differs only in RoHS-compliant plating.	No functional difference; suitable for same designs requiring Pb-free compliance.	Select 2N5551G when tape-and-reel is not required and Pb-free finish is mandatory.
MPSA42	Higher V_CEO (300 V), lower h_FE (min 40), same TO-92 package; f_T = 50 MHz.	Better suited for flyback snubber or HV bias supply switching; less optimal for low-noise audio.	Choose MPSA42 only when >200 V standoff is required and gain/noise performance is secondary.

Compared with 2N5551ZL1, 2N5551G offers identical performance in a Pb-free package but lacks tape-and-reel packaging, while MPSA42 trades gain and noise for higher voltage capability-making it unsuitable as a drop-in replacement unless voltage stress dominates design constraints.

Availability

2N5551ZL1 is available at Aetrix Electronics and suitable for audio preamplifier stages, switching regulator drivers, and industrial sensor interfaces requiring stable component supply, long-term manufacturability, and RoHS-compliant sourcing.

Supply support for 2N5551ZL1 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 specializing in energy-efficient power management, analog, sensors, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The 2N5551ZL1 belongs to onsemi's legacy discrete transistor product line, designed for general-purpose linear amplification and medium-speed switching in cost-sensitive, high-reliability applications across industrial and communications equipment.

FAQ

What is the maximum collector-emitter voltage rating for the 2N5551ZL1?

The 2N5551ZL1 has a guaranteed minimum collector-emitter breakdown voltage V(BR)_CEO of 160 Vdc at I_C = 1.0 mAdc and I_B = 0. This rating is validated per onsemi's 2006 datasheet revision 4 and applies under DC or low-frequency pulsed conditions. Exceeding this voltage risks irreversible avalanche failure.

Does the 2N5551ZL1 have Pb-free construction?

Yes, the 2N5551ZL1 is manufactured with Pb-free terminations and complies with RoHS Directive 2011/65/EU. Its "ZL1" suffix denotes tape-and-reel packaging with Pb-free finish, consistent with onsemi's documented Pb-free strategy outlined in the 2N5550/D datasheet.

What is the typical transition frequency (f_T) of the 2N5551ZL1?

The 2N5551ZL1 has a specified f_T range of 100–300 MHz, measured at I_C = 10 mAdc, V_CE = 10 Vdc, and f = 100 MHz. This value reflects the frequency at which short-circuit current gain drops to unity and confirms suitability for VHF amplification and fast-switching applications.

How does the 2N5551ZL1 differ from the 2N5550 in terms of voltage ratings?

The 2N5551ZL1 provides higher voltage ratings than the 2N5550: V_CEO is 160 V vs. 140 V, and V_CBO is 180 V vs. 160 V. All other parameters-including package, pinout, h_FE range, and thermal characteristics-are otherwise identical per the shared datasheet.

Is the 2N5551ZL1 suitable for low-noise audio applications?

Yes, the 2N5551ZL1 is suitable for low-noise audio applications, with a specified noise figure of 8.0 dB at I_C = 250 μAdc, V_CE = 5.0 Vdc, R_S = 1.0 kΩ, and f = 1.0 kHz. This performance is confirmed in the official onsemi datasheet and makes it appropriate for microphone preamplifier and line-level gain stages.

2N5551ZL1 Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-226-3, TO-92-3 Long Body, Formed Leads

Packaging:: Tape & Box (TB)

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:: 625 mW

Frequency - Transition:: 300MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92 (TO-226)

2N5551ZL1 FAQ

1.How can I place an order for 2N5551ZL1 through Aetrix?

Please submit a Request for Quotation (RFQ) for 2N5551ZL1 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 2N5551ZL1 reliable?

The price and inventory of 2N5551ZL1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2N5551ZL1 is usually 5 days.

3.What payment methods are accepted for 2N5551ZL1?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2N5551ZL1 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2N5551ZL1?

2N5551ZL1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2N5551ZL1 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 2N5551ZL1?

For technical support, including 2N5551ZL1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2N5551ZL1 requirements.

6.How does Aetrix verify that 2N5551ZL1 is sourced from the original manufacturer or authorized distributors?

All 2N5551ZL1 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 2N5551ZL1 meets industry standards.

7.What is the process for return or replacement of 2N5551ZL1?

All 2N5551ZL1 units undergo pre-shipment inspection (PSI). If there is an issue with 2N5551ZL1, 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 2N5551ZL1 part is unused and in its original packaging.

Return procedure for 2N5551ZL1:

1.Submit a request within 90 days.

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

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