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

onsemi BC635_D26Z

Name: BC635_D26Z
Brand: onsemi
SKU: BC635_D26Z
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BC635_D26Z

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-226-3, TO-92-3 (TO-226AA) Formed Leads

Datasheet:: BC635_D26Z.pdf

Description:: TRANS NPN 45V 1A TO-92-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

BC635_D26Z from Fairchild Semiconductor is an NPN epitaxial silicon transistor designed for switching and amplifier applications, with V_CEO = 45 V, I_C = 1 A, P_C = 1 W, h_FE ≥ 25 at I_C = 5 mA, and f_T = 100 MHz - used in low-voltage relay drivers and audio preamplifier stages.

For engineers reviewing the BC635_D26Z datasheet, pinout, applications, or equivalent options, key selection criteria include collector-emitter breakdown voltage, DC current gain at multiple operating points, saturation voltage under defined drive conditions, thermal limits, and TO-92 mechanical compatibility.

Technical Context

This discrete NPN bipolar junction transistor operates in linear amplification and hard-switching modes, supporting DC bias networks with V_BE(on) = 1 V at I_C = 500 mA and V_CE(sat) = 0.5 V at I_C = 500 mA / I_B = 50 mA. Its f_T of 100 MHz enables RF-capable small-signal amplification up to mid-VHF range.

Designed as a complement to BC636/638/640 PNP counterparts, BC635_D26Z shares identical TO-92 package dimensions and terminal assignment (Emitter–Collector–Base), enabling matched-pair implementation in push-pull output stages and differential amplifiers.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	45 V - maximum safe collector-emitter voltage before avalanche breakdown under open-base condition
I_C	1 A - continuous collector current rating defining steady-state power handling capability
P_C	1 W - total device power dissipation limit at T_A = 25°C, derating required above ambient
h_FE	25–250 - DC current gain range across operating conditions (25 @ 5 mA, 250 @ 150 mA)
f_T	100 MHz - unity-gain frequency indicating usable bandwidth for small-signal amplification
V_CE(sat)	0.5 V - low saturation voltage ensures minimal conduction loss in switching applications
T_J	150°C - maximum junction temperature defining thermal reliability boundary

Pinout & Package

BC635_D26Z is housed in a standard TO-92 plastic package with 3 leads. Lead identification follows JEDEC TO-92 outline: flat side facing viewer, leads down, left-to-right = Emitter (1), Collector (2), Base (3).

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current sink terminal	Reference node for base drive; connects to ground or low-impedance return path in common-emitter configurations
2 (Collector)	Current source terminal	Connects to load or supply rail; carries full switched/amplified output current
3 (Base)	Control input terminal	Receives current-limited drive signal; requires series resistor to limit I_B ≤ 100 mA per absolute max rating

Key Features

Feature	Design Value
Complementary PNP pairing	Matched electrical specs and TO-92 footprint with BC636_D26Z for push-pull and differential circuits
High f_T bandwidth	100 MHz gain-bandwidth supports stable small-signal amplification up to ~30 MHz practical design limit
Low V_CE(sat)	0.5 V at I_C/I_B = 10 ensures <100 mW conduction loss in 500 mA switching loads
Wide h_FE operating range	25–250 enables consistent gain control across 5 mA to 150 mA collector currents without re-biasing
JEDEC-standard TO-92	Industry-compatible footprint simplifies board layout, prototyping, and hand-soldering in through-hole designs

Applications

Relay Driver Circuit	Audio Preamp Stage
Use Scenario: Driving 12 V, 40 mA coil relays from microcontroller GPIO pins with level-shifting and isolation. IC Role / Device Role / Timing Role: NPN switch providing current gain and voltage inversion between logic-level input and inductive load. Use Value: V_CE(sat) ≤ 0.5 V minimizes power loss and self-heating during sustained relay activation; h_FE ≥ 25 ensures reliable turn-on with ≤2 mA base drive.	Use Scenario: First-stage voltage amplification in battery-powered portable audio mixers with 3–9 V supply rails. IC Role / Device Role / Timing Role: Common-emitter small-signal amplifier delivering 20–30 dB voltage gain with low harmonic distortion. Use Value: f_T = 100 MHz and h_FE stability across I_C = 1–10 mA support flat 20 Hz–20 kHz response with <0.5% THD at 1 V_pp output.
LED Current Switch	Digital Logic Level Shifter
Use Scenario: Controlling high-brightness white LEDs (3.2 V, 350 mA) from 3.3 V MCU outputs via constant-current switching. IC Role / Device Role / Timing Role: Saturated-mode switch regulating LED current through emitter resistor feedback. Use Value: I_C = 1 A rating and P_C = 1 W allow 350 mA operation with adequate thermal margin at T_A ≤ 60°C.	Use Scenario: Translating 3.3 V LVTTL logic signals to 5 V TTL-compatible levels for legacy peripheral interfacing. IC Role / Device Role / Timing Role: Active pull-up/pull-down stage converting voltage domains while preserving edge integrity. Use Value: Fast switching (t_on/t_off < 100 ns typical) and low C_ob (< 5 pF) maintain signal rise/fall times below 10 ns at 5 V swing.

Relay Driver Circuit

Audio Preamp Stage

Use Scenario: Driving 12 V, 40 mA coil relays from microcontroller GPIO pins with level-shifting and isolation.

IC Role / Device Role / Timing Role: NPN switch providing current gain and voltage inversion between logic-level input and inductive load.

Use Value: V_CE(sat) ≤ 0.5 V minimizes power loss and self-heating during sustained relay activation; h_FE ≥ 25 ensures reliable turn-on with ≤2 mA base drive.

Use Scenario: First-stage voltage amplification in battery-powered portable audio mixers with 3–9 V supply rails.

IC Role / Device Role / Timing Role: Common-emitter small-signal amplifier delivering 20–30 dB voltage gain with low harmonic distortion.

Use Value: f_T = 100 MHz and h_FE stability across I_C = 1–10 mA support flat 20 Hz–20 kHz response with <0.5% THD at 1 V_pp output.

LED Current Switch

Digital Logic Level Shifter

Use Scenario: Controlling high-brightness white LEDs (3.2 V, 350 mA) from 3.3 V MCU outputs via constant-current switching.

IC Role / Device Role / Timing Role: Saturated-mode switch regulating LED current through emitter resistor feedback.

Use Value: I_C = 1 A rating and P_C = 1 W allow 350 mA operation with adequate thermal margin at T_A ≤ 60°C.

Use Scenario: Translating 3.3 V LVTTL logic signals to 5 V TTL-compatible levels for legacy peripheral interfacing.

IC Role / Device Role / Timing Role: Active pull-up/pull-down stage converting voltage domains while preserving edge integrity.

Use Value: Fast switching (t_on/t_off < 100 ns typical) and low C_ob (< 5 pF) maintain signal rise/fall times below 10 ns at 5 V swing.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BC635_T100Z	Same die, tape-and-reel packaging; identical electrical specs and TO-92 footprint	No functional difference; optimized for automated SMT placement rather than manual/hand-soldered assembly	Select BC635_T100Z when using pick-and-place equipment; BC635_D26Z preferred for prototyping and low-volume through-hole builds
PN2222A	Lower V_CEO (40 V vs. 45 V), higher I_C (600 mA vs. 1 A), similar h_FE and f_T; TO-92 compatible but not pin-identical (E-B-C vs. E-C-B)	Not drop-in replaceable due to reversed Collector/Base pinout; requires PCB layout revision	Use PN2222A only if redesigning layout to accommodate E-B-C order; BC635_D26Z maintains direct compatibility with existing BC635-based designs

Compared with BC635_T100Z, BC635_D26Z offers identical performance in a bulk-distribution format ideal for bench testing and repair; versus PN2222A, BC635_D26Z provides higher V_CEO, full 1 A rating, and guaranteed E-C-B pinout - critical for legacy schematic compliance and replacement accuracy.

Availability

BC635_D26Z is available at Aetrix Electronics and suitable for relay driver circuits, audio preamplifier stages, LED current switches, and digital logic level shifters requiring stable component supply and long-term industrial availability.

Supply support for BC635_D26Z 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 manufacturer specializing in power management, analog, and discrete devices before its acquisition by ON Semiconductor in 2016.

The BC635_D26Z belongs to Fairchild's general-purpose bipolar transistor family, engineered for cost-sensitive, high-reliability linear and switching functions in consumer, industrial, and automotive auxiliary systems.

FAQ

What is the pin configuration of BC635_D26Z?

BC635_D26Z uses the standard TO-92 E-C-B pinout: when viewing the flat side with leads pointing downward, the leftmost lead is Emitter (1), center is Collector (2), and rightmost is Base (3). This matches JEDEC TO-92 specification and differs from PN2222A's E-B-C arrangement.

Does BC635_D26Z support switching at 100 kHz?

Yes, BC635_D26Z supports reliable switching at 100 kHz due to its f_T = 100 MHz and low storage time - typical t_on/t_off values are <100 ns. For optimal performance, ensure base drive current exceeds 5× I_C/h_FE(min) and use Baker clamp if fast turn-off is critical.

What is the maximum safe collector current for BC635_D26Z at 70°C ambient?

At T_A = 70°C, BC635_D26Z's P_C derates to ~0.6 W (per 6.25 mW/°C slope from 25°C). With V_CE(sat) ≈ 0.5 V, maximum sustainable I_C is ~1.2 A - but absolute maximum rating remains 1 A continuous. Derated operation must respect I_C ≤ 1 A and T_J ≤ 150°C.

Is BC635_D26Z RoHS compliant?

BC635_D26Z was manufactured prior to RoHS enforcement and does not carry formal RoHS certification. It contains lead in solderable terminations and Pb in the die attach. For new designs requiring RoHS compliance, consider ON Semiconductor's NSS6350MX or MMBT635LT1G as functionally aligned alternatives.

Can BC635_D26Z replace BC637_D26Z in a 60 V circuit?

No - BC635_D26Z has V_CEO = 45 V and V_CER = 45 V, making it unsuitable for 60 V circuits. BC637_D26Z is rated for 60 V V_CEO and 60 V V_CER. Substituting BC635_D26Z risks premature breakdown; always verify voltage ratings against worst-case transient and ripple conditions in the target application.

BC635_D26Z Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-226-3, TO-92-3 (TO-226AA) Formed Leads

Packaging:: Tape & Reel (TR)

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:: 1 W

Frequency - Transition:: 100MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

BC635_D26Z FAQ

1.How can I place an order for BC635_D26Z through Aetrix?

Please submit a Request for Quotation (RFQ) for BC635_D26Z 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 BC635_D26Z reliable?

The price and inventory of BC635_D26Z are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC635_D26Z is usually 5 days.

3.What payment methods are accepted for BC635_D26Z?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC635_D26Z transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BC635_D26Z?

BC635_D26Z orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BC635_D26Z 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 BC635_D26Z?

For technical support, including BC635_D26Z datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC635_D26Z requirements.

6.How does Aetrix verify that BC635_D26Z is sourced from the original manufacturer or authorized distributors?

All BC635_D26Z 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 BC635_D26Z meets industry standards.

7.What is the process for return or replacement of BC635_D26Z?

All BC635_D26Z units undergo pre-shipment inspection (PSI). If there is an issue with BC635_D26Z, 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 BC635_D26Z part is unused and in its original packaging.

Return procedure for BC635_D26Z:

1.Submit a request within 90 days.

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

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