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

onsemi BC635RL1G

Name: BC635RL1G
Brand: onsemi
SKU: BC635RL1G
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BC635RL1G

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: BC635RL1G.pdf

Description:: TRANS NPN 45V 1A TO92

Quantity:: RFQ Add To RFQ list

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Product details

Overview

BC635RL1G from onsemi is an NPN silicon high-current general-purpose transistor in TO-92 package, rated for V_CEO = 45 V, I_C = 1.0 A, P_D = 625 mW at T_A = 25°C, with h_FE = 25–250 (IC = 5–500 mA), and f_T = 200 MHz. It serves as a medium-power switching or linear amplification device in DC-DC converter bias circuits, relay drivers, and LED lamp ballasts.

For engineers reviewing the BC635RL1G datasheet, pinout, applications, or equivalent options, key selection criteria include its 45 V V_CEO, 1.0 A continuous collector current, Pb-free TO-92 packaging, 200 MHz f_T, and verified h_FE range across operating current - critical for stable gain-controlled switching and thermal-limited board-level designs.

Technical Context

The BC635RL1G operates as a discrete bipolar junction transistor with fixed NPN polarity and base-controlled current amplification. Its safe operating area (SOA) is defined up to 1 A/45 V with derating above 25°C ambient, and it exhibits typical V_CE(sat) ≤ 0.5 V at I_C = 500 mA/I_B = 50 mA and V_BE(on) ≤ 1.0 V under same conditions.

Thermal performance is characterized by R_JA = 200°C/W and R_JC = 83.3°C/W, enabling use in low-to-medium power applications where PCB copper area and case-mounting are constrained. Device junction temperature must remain within −55°C to +150°C for reliable operation.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	45 V - Maximum collector-emitter voltage before breakdown; sets upper rail limit in switch-mode or amplifier stages.
I_C (continuous)	1.0 A - Continuous collector current rating; defines max steady-state load drive capability without forced cooling.
P_D @ T_A = 25°C	625 mW - Total power dissipation limit at room ambient; requires thermal derating above 25°C (5.0 mW/°C).
h_FE	25–250 - DC current gain range across 5 mA–500 mA; supports predictable base drive sizing for saturation or active-mode bias.
f_T	200 MHz - Current-gain bandwidth product; confirms suitability for audio-frequency amplification and low-MHz switching control loops.
V_CE(sat)	≤ 0.5 V @ I_C/I_B = 10 - Low saturation voltage minimizes conduction loss in switching applications like relay or solenoid drivers.
R_JA	200°C/W - Junction-to-ambient thermal resistance; determines required PCB copper area and airflow for thermal management.

Pinout & Package

BC635RL1G uses the standard TO-92 (Case 29, Style 14) plastic package with 3 leads, lead-free finish, and JEDEC-compliant dimensions (max height 4.5 mm, body width 3.2 mm). Pin 1 is Emitter, Pin 2 is Collector, Pin 3 is Base - confirmed per marking diagram and ordering information table.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current exit path for majority carriers	Connected to ground or low-side return; base drive referenced to this node in common-emitter configuration.
2 (Collector)	Current entry path for majority carriers	Connected to load or supply rail; carries full switched current; requires trace width and thermal relief per 1 A rating.
3 (Base)	Control terminal for minority carrier injection	Receives current-limited drive signal; base resistor must ensure I_B ≥ I_C/h_FE(min) for guaranteed saturation.

Key Features

Feature	Design Value
Pb-free TO-92 package	Complies with RoHS Directive 2011/65/EU; eliminates lead contamination risk during reflow and end-of-life recycling.
High h_FE consistency	Guaranteed h_FE ≥ 25 at I_C = 5 mA and ≥ 40 at I_C = 150 mA - enables stable bias design across production lots.
Low V_CE(sat)	≤ 0.5 V at I_C = 500 mA - reduces power loss and self-heating in high-duty-cycle switching applications.
Wide T_J range	−55°C to +150°C operation - supports deployment in industrial controls, automotive under-hood modules, and outdoor lighting.
Verified f_T	200 MHz typical - ensures adequate gain margin for feedback-stable audio preamplifiers and PWM error amplifiers.

Applications

Relay Driver Circuit	LED Lamp Ballast
Use Scenario: Driving 12 V/500 mA electromagnetic relay coil in PLC output modules. IC Role / Device Role / Timing Role: NPN switch controlling coil current path between V_CC and ground; base driven by microcontroller GPIO. Use Value: V_CE(sat) ≤ 0.5 V limits relay coil voltage drop to <1% of supply, ensuring reliable pull-in; h_FE ≥ 40 allows 12 mA base drive for 500 mA load.	Use Scenario: Constant-current sink for 350 mA white LED string in streetlight retrofit modules. IC Role / Device Role / Timing Role: Linear current regulator with emitter-follower configuration and sense-resistor feedback. Use Value: 1.0 A I_C rating provides 3× headroom over 350 mA LED current; 625 mW P_D supports 0.7 V × 350 mA ≈ 245 mW dissipation at ambient 60°C.
DC-DC Converter Bias Supply	Audio Preamp Stage
Use Scenario: Providing isolated 5 V bias to gate driver ICs in 48 V input buck converters. IC Role / Device Role / Timing Role: Medium-speed NPN switch in discrete flyback or ZVS auxiliary winding rectifier circuit. Use Value: 200 MHz f_T ensures clean switching edge at 100–500 kHz operating frequencies; 45 V V_CEO accommodates reflected voltage spikes.	Use Scenario: Low-noise voltage amplifier stage in battery-powered portable audio mixers. IC Role / Device Role / Timing Role: Common-emitter small-signal amplifier with emitter degeneration resistor. Use Value: h_FE = 100–250 at 10–50 mA enables precise gain setting; low C_ob = 7.0 pF minimizes high-frequency roll-off in 20 Hz–20 kHz band.

Relay Driver Circuit

LED Lamp Ballast

Use Scenario: Driving 12 V/500 mA electromagnetic relay coil in PLC output modules.

IC Role / Device Role / Timing Role: NPN switch controlling coil current path between V_CC and ground; base driven by microcontroller GPIO.

Use Value: V_CE(sat) ≤ 0.5 V limits relay coil voltage drop to <1% of supply, ensuring reliable pull-in; h_FE ≥ 40 allows 12 mA base drive for 500 mA load.

Use Scenario: Constant-current sink for 350 mA white LED string in streetlight retrofit modules.

IC Role / Device Role / Timing Role: Linear current regulator with emitter-follower configuration and sense-resistor feedback.

Use Value: 1.0 A I_C rating provides 3× headroom over 350 mA LED current; 625 mW P_D supports 0.7 V × 350 mA ≈ 245 mW dissipation at ambient 60°C.

DC-DC Converter Bias Supply

Audio Preamp Stage

Use Scenario: Providing isolated 5 V bias to gate driver ICs in 48 V input buck converters.

IC Role / Device Role / Timing Role: Medium-speed NPN switch in discrete flyback or ZVS auxiliary winding rectifier circuit.

Use Value: 200 MHz f_T ensures clean switching edge at 100–500 kHz operating frequencies; 45 V V_CEO accommodates reflected voltage spikes.

Use Scenario: Low-noise voltage amplifier stage in battery-powered portable audio mixers.

IC Role / Device Role / Timing Role: Common-emitter small-signal amplifier with emitter degeneration resistor.

Use Value: h_FE = 100–250 at 10–50 mA enables precise gain setting; low C_ob = 7.0 pF minimizes high-frequency roll-off in 20 Hz–20 kHz band.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BC637RL1G	V_CEO = 60 V, V_CBO = 60 V (vs. 45 V); otherwise identical package, pinout, and h_FE range.	Preferred where higher supply rails (e.g., 24–48 V systems) require extra voltage margin against transients.	Select BC637RL1G when V_CEO derating headroom is insufficient with BC635RL1G in 36 V+ applications.
BC817-40LT1G	SOT-23 package (vs. TO-92), I_C = 500 mA (vs. 1.0 A), h_FE = 250–630 - higher gain but lower current and power handling.	Suitable for space-constrained PCBs where 500 mA load current suffices and thermal mass is limited.	Choose BC817-40LT1G only if board area is critical and peak load current remains ≤ 500 mA; not a direct replacement due to package and current mismatch.

Compared with BC637RL1G, BC635RL1G offers lower voltage rating but identical thermal and gain behavior; compared with BC817-40LT1G, it delivers double the current and 2.5× the power dissipation in a through-hole package - making it preferable for robust, serviceable, or thermally demanding designs.

Availability

BC635RL1G is available at Aetrix Electronics and suitable for relay drivers, LED lamp ballasts, DC-DC converter bias supplies, and audio preamplifiers requiring stable component supply with RoHS-compliant, through-hole assembly compatibility.

Supply support for BC635RL1G 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 manufacturer specializing in energy-efficient power and signal management solutions, with leadership in automotive, industrial, cloud computing, and IoT markets.

The BC635RL1G belongs to the BC63x family of high-current NPN transistors designed for cost-sensitive, medium-power linear and switching applications in industrial controls, lighting, and power supply subsystems.

FAQ

What is the maximum collector-emitter voltage rating for BC635RL1G?

The BC635RL1G 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 with base open. Exceeding this voltage risks permanent device failure, especially under transient conditions without clamping protection.

Is BC635RL1G compatible with lead-free reflow soldering processes?

Yes, BC635RL1G is explicitly marked as Pb-free in the ordering information and conforms to JEDEC J-STD-020 moisture sensitivity level (MSL) requirements for TO-92 packages. Its termination finish supports standard lead-free reflow profiles with peak temperatures up to 260°C, and no special pre-bake is required for MSL1 handling.

What is the DC current gain (h_FE) range of BC635RL1G across its operating current?

The BC635RL1G exhibits h_FE = 25–100 at I_C = 5 mA, and h_FE = 40–250 at I_C = 500 mA, per the Electrical Characteristics table. This wide spread reflects typical BJT behavior and must be accounted for in base resistor design - using h_FE(min) = 25 ensures saturation under worst-case gain conditions.

Can BC635RL1G be used in linear amplifier configurations?

Yes, BC635RL1G is suitable for linear amplification in common-emitter or emitter-follower topologies, supported by its f_T = 200 MHz, low C_ob = 7.0 pF, and stable h_FE across 1–500 mA. However, its 625 mW power limit and thermal resistance require careful heatsinking or current limiting to avoid thermal runaway in Class-A stages.

How does the thermal resistance of BC635RL1G affect PCB layout?

With R_JA = 200°C/W, BC635RL1G requires ≥ 1.5 cm² of 2-oz copper pour connected to the collector pad (Pin 2) to maintain T_J < 125°C at 500 mA continuous current. Layout must avoid narrow traces, minimize thermal vias distance, and isolate from heat sources - especially critical in enclosed industrial enclosures with still-air convection.

BC635RL1G Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

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

BC635RL1G FAQ

1.How can I place an order for BC635RL1G through Aetrix?

Please submit a Request for Quotation (RFQ) for BC635RL1G 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 BC635RL1G reliable?

The price and inventory of BC635RL1G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC635RL1G is usually 5 days.

3.What payment methods are accepted for BC635RL1G?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC635RL1G transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BC635RL1G?

BC635RL1G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BC635RL1G 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 BC635RL1G?

For technical support, including BC635RL1G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC635RL1G requirements.

6.How does Aetrix verify that BC635RL1G is sourced from the original manufacturer or authorized distributors?

All BC635RL1G 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 BC635RL1G meets industry standards.

7.What is the process for return or replacement of BC635RL1G?

All BC635RL1G units undergo pre-shipment inspection (PSI). If there is an issue with BC635RL1G, 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 BC635RL1G part is unused and in its original packaging.

Return procedure for BC635RL1G:

1.Submit a request within 90 days.

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

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