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

onsemi BC635ZL1

Name: BC635ZL1
Brand: onsemi
SKU: BC635ZL1
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BC635ZL1

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: BC635ZL1.pdf

Description:: TRANS NPN 45V 1A TO92

Quantity:: RFQ Add To RFQ list

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Inventory:3,540

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Product details

Overview

BC635ZL1 from onsemi is an NPN silicon high-current general-purpose transistor in TO-92 package, rated for 45 V_CEO, 1.0 A continuous collector current, and 625 mW power dissipation at T_A = 25°C. It delivers h_FE of 25–250 (at I_C = 5–500 mA), V_CE(sat) ≤ 0.5 V (I_C = 500 mA, I_B = 50 mA), and f_T = 200 MHz - suitable for linear amplification and switching in low-voltage power supplies and relay drivers.

For engineers reviewing the BC635ZL1 datasheet, pinout, applications, or equivalent options, key selection criteria include its 45 V breakdown rating, TO-92 thermal resistance (R_JA = 200°C/W), DC gain range across operating current, saturation voltage under defined drive conditions, and Pb-free tape-and-reel packaging compliance.

Technical Context

The BC635ZL1 operates as a medium-power NPN bipolar junction transistor optimized for robustness in industrial control interfaces and analog signal conditioning. Its design supports linear operation up to 500 mA with stable h_FE and low V_CE(sat), while maintaining safe operating area (SOA) limits per Figure 1 in the datasheet.

It features a fixed three-terminal structure with emitter-base and collector-base junctions exhibiting specified breakdown voltages (V_(BR)EBO = 5.0 V, V_(BR)CBO = 45 V), and dynamic parameters including C_ob = 7.0 pF and C_ib = 50 pF - critical for RF-coupled amplifier stages and fast-switching applications below 200 MHz.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	45 V - Maximum allowable collector-emitter voltage before avalanche breakdown; defines upper rail limit in switch-mode or amplifier designs.
I_C (continuous)	1.0 A - Continuous collector current handling capacity; sets maximum load drive capability without derating.
P_D @ T_A = 25°C	625 mW - Power dissipation limit at ambient temperature; requires heatsinking or airflow above ~50°C ambient.
h_FE	25–250 - DC current gain range across 5 mA–500 mA; enables predictable base drive sizing in both switching and linear modes.
V_CE(sat)	≤ 0.5 V @ I_C = 500 mA, I_B = 50 mA - Low saturation voltage minimizes conduction loss in high-duty-cycle switching circuits.
f_T	200 MHz - Current-gain bandwidth product; supports small-signal amplification up to VHF band with adequate gain margin.

Pinout & Package

BC635ZL1 uses the standard TO-92 (Case 29, Style 14) plastic package with 3.18–4.19 mm width, 4.45–5.20 mm height, and 2.42–2.66 mm lead-to-lead spacing. Thermal resistance is R_JA = 200°C/W and R_JC = 83.3°C/W.

Pin/Terminal	Circuit Role	Design Meaning
1	Emitter	Current sink terminal; connects to ground or low-side return path; base-emitter junction forward-biased during turn-on.
2	Collector	Current source terminal; connects to load or positive supply rail; carries full switched or amplified output current.
3	Base	Control input; requires current-limited drive (typically 1/10 to 1/20 of I_C) to achieve saturation or linear bias.

Key Features

Feature	Design Value
Pb-Free Packaging	Meets RoHS Directive 2011/65/EU; compatible with lead-free reflow profiles (J-STD-020).
High h_FE Consistency	Guaranteed minimum h_FE = 25 at I_C = 5 mA ensures reliable low-current switching without excessive base drive.
Low V_CE(sat)	≤ 0.5 V at I_C/I_B = 10 reduces power loss and self-heating in high-duty-cycle digital switching.
Wide SOA	Supports 500 mA at 20 V (Figure 1) - enables safe operation in inductive load switching with snubberless design.

Applications

Relay Driver Circuit	DC Motor Speed Control
Use Scenario: Driving 12 V, 500 mA electromagnetic relays in PLC I/O modules with microcontroller GPIO output. IC Role / Device Role / Timing Role: NPN switch providing current gain and isolation between logic-level control and coil load. Use Value: V_CE(sat) ≤ 0.5 V ensures <0.25 W coil-side loss; h_FE ≥ 40 at 50 mA base drive simplifies resistor selection.	Use Scenario: Pulse-width modulated (PWM) control of small brushed DC motors in HVAC actuators. IC Role / Device Role / Timing Role: Low-frequency power switch handling 1 A peak motor current at 1–5 kHz PWM frequency. Use Value: SOA supports 500 mA at 20 V (Figure 1); TO-92 package allows compact layout with minimal heatsink requirements.
Linear Voltage Regulator Pass Element	Audio Preamp Stage
Use Scenario: Series pass transistor in adjustable 5–12 V linear regulators powering analog sensor circuitry. IC Role / Device Role / Timing Role: Active current source regulating output voltage via feedback-controlled base bias. Use Value: h_FE stability across 10–100 mA collector current enables precise loop gain tuning and low dropout behavior.	Use Scenario: First-stage small-signal amplifier for electret microphone outputs in voice-enabled IoT devices. IC Role / Device Role / Timing Role: Common-emitter voltage amplifier with resistive bias network and capacitor-coupled input/output. Use Value: f_T = 200 MHz provides >30 dB gain up to 20 kHz; C_ib = 50 pF avoids high-frequency roll-off in audio band.

Relay Driver Circuit

DC Motor Speed Control

Use Scenario: Driving 12 V, 500 mA electromagnetic relays in PLC I/O modules with microcontroller GPIO output.

IC Role / Device Role / Timing Role: NPN switch providing current gain and isolation between logic-level control and coil load.

Use Value: V_CE(sat) ≤ 0.5 V ensures <0.25 W coil-side loss; h_FE ≥ 40 at 50 mA base drive simplifies resistor selection.

Use Scenario: Pulse-width modulated (PWM) control of small brushed DC motors in HVAC actuators.

IC Role / Device Role / Timing Role: Low-frequency power switch handling 1 A peak motor current at 1–5 kHz PWM frequency.

Use Value: SOA supports 500 mA at 20 V (Figure 1); TO-92 package allows compact layout with minimal heatsink requirements.

Linear Voltage Regulator Pass Element

Audio Preamp Stage

Use Scenario: Series pass transistor in adjustable 5–12 V linear regulators powering analog sensor circuitry.

IC Role / Device Role / Timing Role: Active current source regulating output voltage via feedback-controlled base bias.

Use Value: h_FE stability across 10–100 mA collector current enables precise loop gain tuning and low dropout behavior.

Use Scenario: First-stage small-signal amplifier for electret microphone outputs in voice-enabled IoT devices.

IC Role / Device Role / Timing Role: Common-emitter voltage amplifier with resistive bias network and capacitor-coupled input/output.

Use Value: f_T = 200 MHz provides >30 dB gain up to 20 kHz; C_ib = 50 pF avoids high-frequency roll-off in audio band.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BC637ZL1	V_CEO = 60 V (vs. 45 V); otherwise identical pinout, package, and gain/bandwidth specs.	Preferred where higher supply rails (>45 V) or transient overvoltage margin is required.	Select BC637ZL1 when system rail exceeds 45 V but same thermal and drive constraints apply.
BC817-40,215	SOT-23 package (vs. TO-92); h_FE = 250–630; P_D = 310 mW; lower I_C = 500 mA max.	Used in space-constrained PCBs where footprint reduction outweighs power dissipation trade-off.	Choose BC817-40,215 only if board area is critical and peak current stays ≤500 mA with derated power.

Compared with BC635ZL1, BC637ZL1 offers higher voltage tolerance without layout change, while BC817-40,215 trades package size and power for higher gain and surface-mount compatibility - neither is pin-compatible, requiring mechanical and thermal redesign.

Availability

BC635ZL1 is available at Aetrix Electronics and suitable for relay drivers, DC motor controllers, linear regulator pass elements, and audio preamplifiers requiring stable component supply, consistent parametric performance, and RoHS-compliant packaging.

Supply support for BC635ZL1 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 delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The BC635ZL1 belongs to the BC63x family of high-current NPN transistors designed for cost-sensitive, medium-power analog and switching functions in industrial controls, power management, and signal conditioning systems.

FAQ

What is the maximum collector-emitter voltage rating for BC635ZL1?

The BC635ZL1 has a maximum collector-emitter voltage (V_CEO) rating of 45 Vdc, as specified in the Absolute Maximum Ratings table. This value represents the upper limit before avalanche breakdown occurs under open-base conditions with I_C = 10 mA. Exceeding this voltage risks permanent device failure, and derating is recommended for reliability in transient-prone environments.

Does BC635ZL1 support Pb-free soldering processes?

Yes, BC635ZL1 is manufactured in a Pb-free TO-92 package compliant with RoHS Directive 2011/65/EU. It supports standard lead-free reflow profiles per J-STD-020, with peak temperatures up to 260°C. The "ZL1" suffix explicitly denotes tape-and-reel packaging with Pb-free termination finish, verified in the official onsemi ordering information table.

What is the typical DC current gain (h_FE) of BC635ZL1 at 500 mA collector current?

At I_C = 500 mA and V_CE = 2.0 Vdc, the BC635ZL1 exhibits h_FE ranging from 40 (minimum) to 250 (maximum), per the Electrical Characteristics table. The typical value is not published, but Figure 2 shows h_FE ≈ 100–140 in this region - sufficient for designing base drive networks with 5–10 mA I_B to ensure saturation.

Can BC635ZL1 be used in audio amplifier applications?

Yes, BC635ZL1 is suitable for low-frequency audio preamplifier stages due to its f_T = 200 MHz and C_ib = 50 pF, which preserve gain flatness across the 20 Hz–20 kHz band. Its h_FE stability and low noise characteristics (implied by low C_ob = 7.0 pF) support clean small-signal amplification, though it is not optimized for ultra-low-noise microphone front-ends.

What is the thermal resistance from junction to ambient (R_JA) for BC635ZL1?

The BC635ZL1 has a thermal resistance from junction to ambient (R_JA) of 200°C/W when mounted on a standard FR-4 PCB with no heatsink, per the Thermal Characteristics table. This value assumes natural convection cooling and defines the temperature rise per watt dissipated - e.g., 312.5 mW dissipation yields ~62.5°C rise above ambient.

BC635ZL1 Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

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

Packaging:: Bulk

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 1 A

Voltage - Collector Emitter Breakdown (Max):: 45 V

Vce Saturation (Max) @ Ib, Ic:: 500mV @ 50mA, 500mA

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 40 @ 150mA, 2V

Power - Max:: 625 mW

Frequency - Transition:: 200MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

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

BC635ZL1 FAQ

1.How can I place an order for BC635ZL1 through Aetrix?

Please submit a Request for Quotation (RFQ) for BC635ZL1 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 BC635ZL1 reliable?

The price and inventory of BC635ZL1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC635ZL1 is usually 5 days.

3.What payment methods are accepted for BC635ZL1?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC635ZL1 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BC635ZL1?

BC635ZL1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BC635ZL1 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 BC635ZL1?

For technical support, including BC635ZL1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC635ZL1 requirements.

6.How does Aetrix verify that BC635ZL1 is sourced from the original manufacturer or authorized distributors?

All BC635ZL1 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 BC635ZL1 meets industry standards.

7.What is the process for return or replacement of BC635ZL1?

All BC635ZL1 units undergo pre-shipment inspection (PSI). If there is an issue with BC635ZL1, 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 BC635ZL1 part is unused and in its original packaging.

Return procedure for BC635ZL1:

1.Submit a request within 90 days.

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

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