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Home > Products > Discrete Semiconductor Products > Transistors > FETs, MOSFETs > FETs, MOSFETs

NXP Semiconductors BS108,126

Name: BS108,126
Brand: NXP Semiconductors
SKU: BS108,126
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BS108,126

Manufacturer:: NXP Semiconductors

Category:: FETs, MOSFETs

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

Datasheet:: BS108,126.pdf

Description:: MOSFET N-CH 200V 300MA TO92-3

Quantity:: RFQ Add To RFQ list

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Inventory:6,039

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Product details

Overview

BS108,126 from NXP Semiconductors (formerly Philips) is an N-channel enhancement-mode vertical D-MOS transistor in SOT54 (TO-92) package, rated for 200 V drain-source voltage, 300 mA DC drain current, and 5 Ω maximum R_DS(on) at V_GS = 2.8 V. It serves as a low-power switching device in telephone line current interruptors and relay drivers.

For engineers reviewing the BS108,126 datasheet, BS108,126 pinout, BS108,126 application, or BS108,126 equivalent, key selection considerations include gate-threshold voltage range (0.4–1.8 V), fast switching times (6–10 ns turn-on, 49–60 ns turn-off), and thermal resistance (125 K/W junction-to-ambient).

Technical Context

This discrete MOSFET uses vertical D-MOS architecture to achieve high breakdown voltage (200 V) with low on-resistance (typ. 2.7 Ω) and no secondary breakdown limitation. Its gate-threshold voltage (V_GS(th)) is specified at 1 mA drain current, enabling direct interface with CMOS and TTL logic without level-shifting.

Switching performance is characterized at V_DD = 50 V and I_D = 250 mA, with input capacitance (C_iss) of 100–120 pF and reverse transfer capacitance (C_rss) of 10–15 pF - parameters critical for high-speed line driver design and minimizing Miller effect in transformer-coupled circuits.

Key Specifications

Parameter	Value and Actual Design Meaning
V_DS	200 V DC - supports operation across telephone line surge transients and relay coil flyback voltages without breakdown.
I_D (DC)	300 mA - sufficient for driving small relays, LED indicators, and low-current analog switches in telecom equipment.
R_DS(on)	2.7 Ω typ. at V_GS = 2.8 V - ensures <1 V drop at 300 mA, minimizing conduction loss in battery-powered or thermally constrained designs.
V_GS(th)	0.4–1.8 V - enables reliable turn-on from 3.3 V or 5 V logic outputs without external gate biasing.
t_on/t_off	6–10 ns / 49–60 ns - supports >10 MHz switching in line transformer drivers and pulse-width modulated signal paths.
C_iss	100–120 pF - defines gate drive strength requirement; compatible with standard logic buffers without added gate drivers.

Pinout & Package

SOT54 (TO-92) plastic through-hole package with 3 leads; body length 14.5 mm, lead pitch 2.54 mm, drain lead requires ≥10 × 10 mm PCB copper pad for thermal management per datasheet note.

Pin/Terminal	Circuit Role	Design Meaning
1	Source	Reference node for gate control; tied to ground or low-side return path in common-source switching configurations.
2	Gate	Control terminal; high-impedance input requiring minimal drive current; sensitive to ESD due to thin oxide.
3	Drain	High-voltage output node; connected to load (e.g., relay coil or transformer primary); thermally coupled to PCB pad.

Key Features

Feature	Design Value
No secondary breakdown	Enables safe operation under inductive load switching without SOA derating curves or snubber networks.
Direct CMOS/TTL interface	Eliminates need for gate resistors or level shifters when driven by standard logic families at 3.3 V or 5 V.
High-speed switching	Sub-10 ns turn-on and <60 ns turn-off support precise timing in line signaling and pulse generation circuits.
Low gate leakage	IGSS ≤ ±100 nA at ±20 V ensures stable gate bias over time and low standby power in always-on applications.

Applications

Telephone Line Interruptor	Relay Driver
Use Scenario: Interrupting DC loop current in POTS telephone line interface circuits during call setup or hook-switch events. IC Role / Device Role / Timing Role: Low-side switch controlling 48 V line feed current; activated by microcontroller GPIO. Use Value: 200 V rating withstands ring voltage surges up to 160 V; 300 mA rating matches typical loop current limits.	Use Scenario: Driving 5 V/12 V electromagnetic relays in industrial control modules and telecom interface cards. IC Role / Device Role / Timing Role: Solid-state replacement for mechanical contacts; switched at <1 kHz for relay coil energization/de-energization. Use Value: 5 Ω R_DS(on) limits coil voltage drop to <1.5 V at 300 mA, ensuring reliable relay pull-in without auxiliary boost circuitry.
Line Transformer Driver	High-Speed Signal Switch
Use Scenario: Driving center-tapped line transformers in DSL or ISDN data transmission interfaces. IC Role / Device Role / Timing Role: Half-bridge low-side switch in push-pull configuration; toggled at data symbol rates up to 2 MHz. Use Value: 100–120 pF C_iss and 10–15 pF C_rss minimize switching distortion and enable clean edge fidelity in differential signaling paths.	Use Scenario: Routing analog or digital signals in test equipment multiplexers and programmable gain stages. IC Role / Device Role / Timing Role: Normally-open analog switch controlled by logic-level enable; operated in linear region for low-distortion signal pass-through. Use Value: 2.7 Ω R_DS(on) provides <0.1% gain error at 1 kΩ load; V_GS(th) spread allows predictable turn-on across temperature.

Telephone Line Interruptor

Relay Driver

Use Scenario: Interrupting DC loop current in POTS telephone line interface circuits during call setup or hook-switch events.

IC Role / Device Role / Timing Role: Low-side switch controlling 48 V line feed current; activated by microcontroller GPIO.

Use Value: 200 V rating withstands ring voltage surges up to 160 V; 300 mA rating matches typical loop current limits.

Use Scenario: Driving 5 V/12 V electromagnetic relays in industrial control modules and telecom interface cards.

IC Role / Device Role / Timing Role: Solid-state replacement for mechanical contacts; switched at <1 kHz for relay coil energization/de-energization.

Use Value: 5 Ω R_DS(on) limits coil voltage drop to <1.5 V at 300 mA, ensuring reliable relay pull-in without auxiliary boost circuitry.

Line Transformer Driver

High-Speed Signal Switch

Use Scenario: Driving center-tapped line transformers in DSL or ISDN data transmission interfaces.

IC Role / Device Role / Timing Role: Half-bridge low-side switch in push-pull configuration; toggled at data symbol rates up to 2 MHz.

Use Value: 100–120 pF C_iss and 10–15 pF C_rss minimize switching distortion and enable clean edge fidelity in differential signaling paths.

Use Scenario: Routing analog or digital signals in test equipment multiplexers and programmable gain stages.

IC Role / Device Role / Timing Role: Normally-open analog switch controlled by logic-level enable; operated in linear region for low-distortion signal pass-through.

Use Value: 2.7 Ω R_DS(on) provides <0.1% gain error at 1 kΩ load; V_GS(th) spread allows predictable turn-on across temperature.

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-voltage, low-current MOSFET switching applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
BS170,118	Higher R_DS(on) (5–10 Ω), lower V_DS (60 V), same SOT54 package and pinout.	Not suitable for 200 V telephone line applications; limited to ≤60 V logic-level loads.	Select BS170,118 only when operating voltage is <60 V and higher on-resistance is acceptable.
2N7000	Similar V_DS (60 V), higher V_GS(th) (1–3 V), TO-92 package but different pinout (drain/source swapped vs. BS108,126).	Requires PCB layout revision due to non-pin-compatible pin assignment; unsuitable for drop-in replacement.	Choose 2N7000 only if redesign accommodates pinout change and system voltage stays ≤60 V.

Compared with BS170,118 and 2N7000, the BS108,126 uniquely combines 200 V capability, sub-2 V threshold, and SOT54 compatibility - making it irreplaceable in legacy telecom line interface designs where voltage margin and direct logic drive are mandatory.

Availability

BS108,126 is available at Aetrix Electronics and suitable for telephone line interruptors, relay drivers, line transformer drivers, and high-speed signal switching applications requiring stable component supply and long-lifecycle support.

Supply support for BS108,126 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

NXP Semiconductors, formerly Philips Semiconductors, is a global semiconductor leader focused on secure connectivity solutions for automotive, industrial, and communication markets.

The BS108,126 belongs to NXP's legacy discrete power MOSFET product line, designed specifically for robust, low-cost switching in telecom infrastructure and electromechanical interface circuits.

FAQ

What is the maximum continuous drain current rating for BS108,126?

The BS108,126 is rated for 300 mA DC drain current at T_amb ≤25 °C with proper PCB thermal pad. Derating applies above 25 °C ambient, reaching zero current at 150 °C junction temperature. This rating is validated under IEC 60134 limiting values with 10 × 10 mm drain pad per datasheet note 1.

Does BS108,126 support direct connection to 3.3 V logic outputs?

Yes - the BS108,126 has a gate-threshold voltage range of 0.4–1.8 V, ensuring full enhancement at 3.3 V gate drive. Its low gate charge and 100–120 pF input capacitance allow clean switching without external gate drivers when driven by standard 3.3 V CMOS outputs.

Is BS108,126 pin-compatible with the 2N7000 in TO-92 packages?

No - although both use TO-92 form factor, the BS108,126 (SOT54) has drain on pin 3, source on pin 1, while the 2N7000 assigns drain to pin 2 and source to pin 3. This pinout mismatch prevents direct substitution without PCB modification.

What is the thermal resistance of BS108,126 and how does it affect layout?

The BS108,126 has a junction-to-ambient thermal resistance of 125 K/W when mounted with ≤4 mm lead length and a minimum 10 × 10 mm copper pad on the drain lead. Layout must allocate this pad area on the PCB to maintain T_j ≤150 °C at rated power dissipation.

Can BS108,126 be used in avalanche energy applications?

No - the BS108,126 datasheet does not specify avalanche ratings or ruggedness. It is characterized for linear and switching operation within absolute maximum ratings only; operation beyond V_DS = 200 V or unclamped inductive switching is not supported.

BS108,126 Specifications

Product attributes: Attribute value

Manufacturer:: NXP Semiconductors

Series:: -

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

Packaging:: Tape & Box (TB)

Product Status:: Obsolete

FET Type:: N-Channel

Technology:: MOSFET (Metal Oxide)

Drain to Source Voltage (Vdss):: 200 V

Current - Continuous Drain (Id) @ 25°C:: 300mA (Ta)

Drive Voltage (Max Rds On, Min Rds On):: 2.8V

Rds On (Max) @ Id, Vgs:: 5Ohm @ 100mA, 2.8V

Vgs(th) (Max) @ Id:: 1.8V @ 1mA

Gate Charge (Qg) (Max) @ Vgs:: -

Vgs (Max):: ±20V

Input Capacitance (Ciss) (Max) @ Vds:: 120 pF @ 25 V

FET Feature:: -

Power Dissipation (Max):: 1W (Ta)

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

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

BS108,126 FAQ

1.How can I place an order for BS108,126 through Aetrix?

Please submit a Request for Quotation (RFQ) for BS108,126 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 BS108,126 reliable?

The price and inventory of BS108,126 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BS108,126 is usually 5 days.

3.What payment methods are accepted for BS108,126?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BS108,126 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BS108,126?

BS108,126 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BS108,126 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 BS108,126?

For technical support, including BS108,126 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BS108,126 requirements.

6.How does Aetrix verify that BS108,126 is sourced from the original manufacturer or authorized distributors?

All BS108,126 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 BS108,126 meets industry standards.

7.What is the process for return or replacement of BS108,126?

All BS108,126 units undergo pre-shipment inspection (PSI). If there is an issue with BS108,126, 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 BS108,126 part is unused and in its original packaging.

Return procedure for BS108,126:

1.Submit a request within 90 days.

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

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