BC337-040G NPN Bipolar Junction Transistor Equivalent & Substitute Parts

Part Overview

The BC337-040G is an NPN bipolar junction transistor manufactured by onsemi, rated for 45 V collector-emitter breakdown voltage and 800 mA maximum collector current. This device is packaged in the TO-92 (TO-226-3) through-hole configuration and is rated for 625 mW maximum power dissipation. The BC337-040G is classified as obsolete; therefore, equivalent and substitute parts are necessary for ongoing design support, production continuity, and component sourcing.

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
DC Current Gain (hFE) (Min) @ Ic, Vce	250 @ 100mA, 1V	—
Vce Saturation (Max) @ Ib, Ic	700mV @ 50mA, 500mA	—
Operating Temperature Range	-55 to 150	°C
Mounting Type	Through Hole	—
Package / Case	TO-226-3, TO-92-3 Long Body	—

Substitute Part Grouping Explanation

Substitution of the BC337-040G is determined by electrical and mechanical compatibility across the following critical parameters:

Electrical Compatibility Criteria:

Transistor type must be NPN
Collector-emitter breakdown voltage (VCEO) must be ≥ 45 V
Maximum collector current (Ic) must be ≥ 800 mA
Maximum power dissipation must be ≥ 625 mW
DC current gain (hFE) must support the application's biasing requirements
Vce saturation characteristics must be compatible with switching or linear operation

Mechanical Compatibility Criteria:

Mounting type must be through-hole
Package must be TO-92 or TO-92-3 compatible (pin configuration TO-226-3 or equivalent)

Compliance and Status Considerations:

Active product status is preferred for long-term availability
RoHS3 compliance status is noted where applicable
REACH compliance status is uniform across all listed parts

Substitute parts are grouped into two categories: Direct Substitutes (electrically and mechanically equivalent with identical or superior ratings) and Similar Substitutes (compatible within specified parameters but with variations in secondary characteristics such as transition frequency or DC current gain).

Parameter Comparison

Part Number	Manufacturer	Product Status	Ic (Max) [mA]	VCEO (Max) [V]	Power (Max) [mW]	hFE (Min) @ Ic, Vce	fT [MHz]	Vce Sat (Max) @ Ib, Ic	Package	Temp Range [°C]
BC337-040G	onsemi	Obsolete	800	45	625	250 @ 100mA, 1V	210	700mV @ 50mA, 500mA	TO-92-3	-55 to 150
BC33740BU	onsemi	Active	800	45	625	250 @ 100mA, 1V	100	700mV @ 50mA, 500mA	TO-92-3	-55 to 150
BC337-25-AP	Micro Commercial Co	Obsolete	800	45	625	160 @ 100mA, 1V	210	700mV @ 50mA, 500mA	TO-92-3	-55 to 150
BC33716BU	Fairchild Semiconductor	Active	800	45	625	100 @ 100mA, 1V	100	700mV @ 50mA, 500mA	TO-92-3	-55 to 150
BC33725BU	Fairchild Semiconductor	Active	800	45	625	160 @ 100mA, 1V	100	700mV @ 50mA, 500mA	TO-92-3	-55 to 150
2N4401BU	onsemi	Active	600	40	625	100 @ 150mA, 1V	250	750mV @ 50mA, 500mA	TO-92-3	-55 to 150
ZTX450	Diodes Incorporated	Active	1000	45	1000	100 @ 150mA, 10V	150	250mV @ 15mA, 150mA	E-Line (TO-92 compatible)	-55 to 200

Engineering Selection Recommendations

Direct Substitutes (Preferred for Replacement):

BC33740BU (onsemi) is the primary direct substitute for BC337-040G. Both parts share identical electrical ratings for collector current (800 mA), collector-emitter breakdown voltage (45 V), power dissipation (625 mW), and DC current gain (250 @ 100mA, 1V). BC33740BU is active product status, ensuring long-term availability and supply chain continuity. The transition frequency is reduced from 210 MHz to 100 MHz; this reduction does not affect compatibility in applications where the original 210 MHz specification was not a critical design requirement. Both parts are packaged in TO-92-3 and operate across the same temperature range (-55°C to 150°C).

BC337-25-AP (Micro Commercial Co) is electrically compatible with BC337-040G across all critical parameters: 800 mA collector current, 45 V breakdown voltage, 625 mW power rating, and 210 MHz transition frequency. However, DC current gain is reduced to 160 @ 100mA, 1V. This part is classified as obsolete; therefore, it is suitable only for replacement in existing designs where supply exists and long-term sourcing is not required.

Similar Substitutes (Application-Dependent Selection):

BC33716BU and BC33725BU (Fairchild Semiconductor) are active products with identical electrical ratings to BC337-040G for collector current, breakdown voltage, and power dissipation. Both are packaged in TO-92-3. BC33716BU has DC current gain of 100 @ 100mA, 1V, while BC33725BU has 160 @ 100mA, 1V. Both have transition frequency of 100 MHz. These parts are suitable for applications where the reduced transition frequency does not impact circuit performance and where lower DC current gain is acceptable for the biasing network.

2N4401BU (onsemi) is a similar substitute with reduced electrical ratings: maximum collector current is 600 mA (versus 800 mA), and collector-emitter breakdown voltage is 40 V (versus 45 V). This part is active product status and packaged in TO-92-3. Selection of 2N4401BU is appropriate only for applications where the lower current and voltage ratings are sufficient and where the higher transition frequency (250 MHz) provides design advantage.

ZTX450 (Diodes Incorporated) is a similar substitute with enhanced electrical ratings: maximum collector current is 1 A (versus 800 mA) and maximum power dissipation is 1 W (versus 625 mW). The package is E-Line (TO-92 compatible), which maintains mechanical compatibility. Operating temperature range extends to 200°C. ZTX450 is active product status. Selection is appropriate for applications requiring higher current capacity or extended temperature operation. Vce saturation characteristics differ significantly (250 mV @ 15mA, 150mA versus 700 mV @ 50mA, 500mA), requiring circuit verification for switching applications.

Compliance Status:

All active substitute parts (BC33740BU, BC33716BU, BC33725BU, 2N4401BU, ZTX450) are RoHS3 compliant and REACH unaffected. All parts carry ECCN classification EAR99 and HTSUS code 8541.21.0075 (or 8541.29.0075 for ZTX450), confirming regulatory alignment.

Frequently Asked Questions (FAQ)

Q: Can BC33740BU directly replace BC337-040G in all applications?

A: BC33740BU is electrically and mechanically compatible with BC337-040G for all critical parameters: 800 mA collector current, 45 V breakdown voltage, 625 mW power dissipation, and identical DC current gain (250 @ 100mA, 1V). The transition frequency is reduced from 210 MHz to 100 MHz. In applications where the circuit does not depend on the 210 MHz specification, BC33740BU is a direct replacement. For high-frequency switching applications operating near 210 MHz, circuit performance must be verified.

Q: What is the difference between "Direct Substitute" and "Similar Substitute" classifications?

A: Direct substitutes meet or exceed all electrical and mechanical specifications of the original part. BC33740BU and BC337-25-AP are direct substitutes because they maintain 800 mA collector current, 45 V breakdown voltage, and 625 mW power rating. Similar substitutes are compatible within the application's electrical requirements but have variations in secondary parameters. For example, 2N4401BU has reduced collector current (600 mA) and breakdown voltage (40 V), making it suitable only for applications where these lower ratings are acceptable.

Q: Why is 2N4401BU listed as a substitute if it has lower current and voltage ratings?

A: 2N4401BU is listed as a similar substitute because it is electrically compatible for applications that do not require the full 800 mA collector current or 45 V breakdown voltage. The part is active product status with good availability. Selection depends on the specific circuit requirements. If the application requires 800 mA at 45 V, 2N4401BU is not suitable. If the application operates at lower current and voltage levels, 2N4401BU is a valid alternative.

Q: Is the TO-92-3 package identical across all substitute parts?

A: All substitute parts except ZTX450 are packaged in TO-92-3 (TO-226-3), which is mechanically identical to the original BC337-040G. ZTX450 is packaged in E-Line (TO-92 compatible), which maintains the same three-pin through-hole configuration and pin spacing as TO-92-3. Pin assignment (collector, base, emitter) is identical across all parts. Physical board layout compatibility is maintained.

Q: Can ZTX450 be used in place of BC337-040G?

A: ZTX450 is mechanically compatible (TO-92 compatible package) and electrically compatible for voltage rating (45 V). However, ZTX450 has enhanced specifications: 1 A collector current (versus 800 mA) and 1 W power dissipation (versus 625 mW). Vce saturation characteristics differ significantly. ZTX450 is suitable for applications requiring higher current capacity or extended temperature operation (-55°C to 200°C). For direct replacement in existing designs, circuit verification is required due to the different saturation characteristics.

Q: What is the impact of reduced DC current gain in substitute parts?

A: DC current gain (hFE) determines the base current required to achieve a specified collector current. BC337-040G has hFE of 250 @ 100mA, 1V. Substitute parts have lower values: BC33716BU has 100, BC33725BU has 160, and 2N4401BU has 100. Lower hFE requires higher base current for the same collector current. In voltage amplifier circuits, lower hFE reduces voltage gain. In switching circuits, lower hFE requires larger base drive resistors or additional base current. Circuit biasing networks must be recalculated for parts with reduced hFE.

Q: Are all substitute parts RoHS3 compliant?

A: All active substitute parts (BC33740BU, BC33716BU, BC33725BU, 2N4401BU, ZTX450) are RoHS3 compliant. The original BC337-040G is classified as obsolete and does not carry RoHS3 compliance status. BC337-25-AP is also obsolete. For new designs or production requiring RoHS3 compliance, active substitute parts must be selected.

Q: What is the operating temperature range for each substitute?

A: BC337-040G, BC33740BU, BC337-25-AP, BC33716BU, BC33725BU, and 2N4401BU all operate across -55°C to 150°C. ZTX450 extends the upper temperature limit to 200°C. Selection of ZTX450 is appropriate for applications requiring operation above 150°C.

Q: Can substitute parts be mixed in the same production batch?

A: Mixing substitute parts with different DC current gain values (hFE) in the same circuit or production batch is not recommended without circuit verification. Different hFE values require different base biasing networks. If multiple substitute parts must be used, each part number should be evaluated independently for the specific circuit application, and biasing networks should be adjusted accordingly. For production consistency, a single substitute part should be selected and qualified for the entire production run.

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