BC337-40RL1G Equivalent & Substitute Parts

Part Overview

The BC337-40RL1G is an NPN bipolar junction transistor manufactured by onsemi, designed for general-purpose switching and amplification applications. This device features a 45 V collector-emitter breakdown voltage, 800 mA maximum collector current, and 625 mW power dissipation capability in a Through Hole TO-92 package. The BC337-40RL1G is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement continuity.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	45	V
Current - Collector (Ic) (Max)	800	mA
Power - Max	625	mW
Frequency - Transition	210	MHz
Vce Saturation (Max) @ Ib, Ic	700mV @ 50mA, 500mA	V
DC Current Gain (hFE) (Min) @ Ic, Vce	250 @ 100mA, 1V	—
Operating Temperature Range	-55 to 150	°C
Mounting Type	Through Hole	—
Package / Case	TO-226-3, TO-92-3 Long Body (Formed Leads)	—

Substitute Part Grouping Explanation

Substitution of the BC337-40RL1G is determined by electrical and mechanical compatibility across the following critical parameters:

Electrical Compatibility Criteria:

Transistor Type: NPN (required match)
Voltage - Collector Emitter Breakdown (Max): 45 V or greater
Current - Collector (Ic) (Max): 800 mA or greater
Power - Max: 625 mW or greater
Vce Saturation (Max) @ Ib, Ic: 700mV @ 50mA, 500mA or lower
Operating Temperature Range: -55°C to 150°C or equivalent coverage

Mechanical Compatibility Criteria:

Mounting Type: Through Hole (required match)
Package / Case: TO-92-3 or TO-226-3 (required match)

Substitute parts are grouped into two categories:

Direct Substitutes: Parts meeting all electrical and mechanical parameters with identical or superior specifications and active product status.

Similar Substitutes: Parts meeting core electrical and mechanical parameters with minor variations in transition frequency or DC current gain, or with obsolete product status.

Parameter Comparison

Part Number	Manufacturer	Ic (Max) mA	Vce Breakdown (Max) V	Power (Max) mW	Frequency (Transition) MHz	hFE (Min) @ 100mA, 1V	Vce Sat (Max) @ 50mA, 500mA mV	Package	Product Status
BC337-40RL1G	onsemi	800	45	625	210	250	700	TO-92-3	Obsolete
BC33740TA	onsemi	800	45	625	100	250	700	TO-92-3	Active
BC33725TA	onsemi	800	45	625	100	160	700	TO-92-3	Active
BC33725TAR	onsemi	800	45	625	100	160	700	TO-92-3	Active
BC33716TA	Fairchild Semiconductor	800	45	625	100	100	700	TO-92-3	Active
BC33725TFR	Fairchild Semiconductor	800	45	625	100	160	700	TO-92-3	Active
BC337-25-AP	Micro Commercial Co	800	45	625	210	160	700	TO-92-3	Obsolete
2N4401BU	onsemi	600	40	625	250	100	750	TO-92-3	Active

Engineering Selection Recommendations

Primary Substitutes (Active Status, Full Electrical Compatibility):

BC33740TA (onsemi) is the recommended direct substitute. This part maintains identical electrical specifications to the BC337-40RL1G across all critical parameters: 800 mA collector current, 45 V breakdown voltage, 625 mW power rating, and 700 mV saturation voltage. The transition frequency is reduced from 210 MHz to 100 MHz, which is acceptable for most general-purpose switching applications. BC33740TA carries active product status and RoHS3 compliance, ensuring long-term availability and regulatory alignment.

BC33725TA and BC33725TAR (onsemi) are functionally equivalent alternatives with identical electrical performance to BC33740TA. Both maintain the same core specifications and offer superior inventory availability (65,300 and 10,204 units respectively). These parts are suitable for applications where the 100 MHz transition frequency meets design requirements.

Secondary Substitutes (Active Status, Minor Parameter Variations):

BC33716TA (Fairchild Semiconductor) and BC33725TFR (Fairchild Semiconductor) provide electrical compatibility with reduced DC current gain (hFE minimum of 100 @ 100mA, 1V compared to 250 for the original part). These substitutes are applicable in circuits where base drive current is not constrained and the lower gain does not impact circuit performance.

2N4401BU (onsemi) is an active alternative with reduced electrical specifications: 600 mA maximum collector current and 40 V breakdown voltage. This part is suitable only for applications where the lower current and voltage ratings are acceptable. The higher transition frequency (250 MHz) and lower saturation voltage (750 mV) may provide performance benefits in specific switching applications.

Obsolete Status Alternatives:

BC337-25-AP (Micro Commercial Co) maintains the 210 MHz transition frequency of the original BC337-40RL1G but carries obsolete product status, limiting its suitability for new designs despite electrical compatibility.

Frequently Asked Questions (FAQ)

Q: Can BC33740TA directly replace BC337-40RL1G in all applications?

A: BC33740TA is electrically compatible with BC337-40RL1G across all critical parameters: collector current (800 mA), breakdown voltage (45 V), power dissipation (625 mW), and saturation voltage (700 mV @ 50mA, 500mA). The reduced transition frequency (100 MHz vs. 210 MHz) is acceptable for general-purpose switching and amplification. Both use identical TO-92-3 Through Hole packaging. Substitution is valid for applications not requiring the higher frequency response of the original part.

Q: What is the difference between BC33725TA and BC33725TAR?

A: BC33725TA and BC33725TAR are functionally identical in electrical specifications. Both are manufactured by onsemi, feature 800 mA collector current, 45 V breakdown voltage, and 100 MHz transition frequency. The primary difference is packaging designation: BC33725TA is supplied in Cut Tape (CT) format with 65,300 units in stock, while BC33725TAR is also in Cut Tape format with 10,204 units available. Selection between these parts depends on procurement quantity requirements and supplier availability.

Q: Why does 2N4401BU have different electrical specifications?

A: 2N4401BU is a distinct device family with inherently different electrical characteristics. It features 600 mA maximum collector current (versus 800 mA) and 40 V breakdown voltage (versus 45 V). These reductions reflect the device's design for lower-power applications. The higher transition frequency (250 MHz) and lower saturation voltage (750 mV) indicate optimization for faster switching performance. 2N4401BU is suitable only for applications where the reduced current and voltage ratings are compatible with circuit requirements.

Q: Are Fairchild Semiconductor parts (BC33716TA, BC33725TFR) equivalent to onsemi parts?

A: BC33716TA and BC33725TFR are functionally compatible with onsemi equivalents in terms of electrical performance and TO-92-3 packaging. However, both Fairchild parts feature reduced DC current gain (hFE minimum of 100 @ 100mA, 1V) compared to onsemi parts (hFE minimum of 160 to 250). This lower gain requires higher base drive current for equivalent collector current. Substitution is valid in circuits where base drive current is available and the lower gain does not compromise circuit operation.

Q: What is the significance of the TO-92-3 package specification?

A: TO-92-3 is a Through Hole package with three leads (Base, Collector, Emitter) in a standardized physical configuration. All substitute parts listed maintain this package type, ensuring mechanical compatibility with existing printed circuit board layouts and assembly processes. The "Formed Leads" designation indicates pre-bent leads for direct insertion into standard TO-92 footprints. Package compatibility is a mandatory requirement for direct substitution.

Q: Why is BC337-40RL1G classified as obsolete?

A: Obsolete product status indicates that the manufacturer (onsemi) has discontinued production and support for this specific part number. Active alternatives such as BC33740TA, BC33725TA, and BC33725TAR provide equivalent or superior electrical performance with ongoing manufacturer support, compliance certifications, and guaranteed long-term availability. New designs should utilize active alternatives to ensure supply chain continuity and regulatory compliance.

Q: Can I use BC337-25-AP as a substitute despite its obsolete status?

A: BC337-25-AP maintains electrical compatibility with BC337-40RL1G, including the 210 MHz transition frequency. However, obsolete product status limits its practical application. Inventory availability is finite (8,300 units), and manufacturer support is discontinued. For new designs or long-term production, active alternatives such as BC33740TA are strongly preferred to ensure supply chain reliability and regulatory compliance.

Q: What compliance certifications apply to these substitute parts?

A: BC33740TA, BC33725TA, BC33725TAR, BC33716TA, and BC33725TFR all carry RoHS3 compliance certification, indicating conformance to Restriction of Hazardous Substances regulations. All listed parts are REACH Unaffected and classified under ECCN EAR99 for export control purposes. These certifications ensure regulatory alignment for commercial and industrial applications. The original BC337-40RL1G and BC337-25-AP do not specify RoHS compliance, making active alternatives preferable for regulated applications.

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