BC237C Equivalent & Substitute Parts

Part Overview

The BC237C is an NPN bipolar junction transistor manufactured by onsemi, rated for 45 V collector-emitter breakdown voltage and 100 mA maximum collector current. This device is packaged in the TO-92 (TO-226-3) through-hole configuration and is classified as obsolete. The BC237C operates across a temperature range of -55°C to 150°C and delivers 350 mW maximum power dissipation with a transition frequency of 200 MHz.

Due to its obsolete product status, equivalent and substitute parts are necessary to maintain design continuity and ensure component availability for new production runs and field replacements. Substitute devices must maintain electrical compatibility within the specified parameter ranges while meeting current manufacturing and compliance standards.

Key Parameters

Parameter	BC237C Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	45	V
Current - Collector (Ic) (Max)	100	mA
Vce Saturation (Max) @ Ib, Ic	600 mV @ 5 mA, 100 mA	—
Current - Collector Cutoff (Max)	15	nA
DC Current Gain (hFE) (Min) @ Ic, Vce	380 @ 2 mA, 5 V	—
Power - Max	350	mW
Frequency - Transition	200	MHz
Operating Temperature	-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 BC237C is determined by strict adherence to the following electrical and mechanical parameters:

Primary Substitution Criteria:

Transistor Type: NPN (mandatory match)
Voltage - Collector Emitter Breakdown (Max): minimum 45 V
Current - Collector (Ic) (Max): minimum 100 mA
Vce Saturation (Max) @ Ib, Ic: 600 mV @ 5 mA, 100 mA (or lower)
Current - Collector Cutoff (Max): 15 nA or lower
Mounting Type: Through Hole
Package / Case: TO-92 or TO-92-compatible configurations

Secondary Compatibility Factors:

Operating Temperature Range: must encompass -55°C to 150°C minimum
Power Dissipation: minimum 350 mW (higher values acceptable)
DC Current Gain (hFE): minimum 200 @ 2 mA, 5 V (BC237C specifies 380 minimum)
Frequency - Transition: 150 MHz or higher (BC237C specifies 200 MHz)

Substitute parts are grouped into two categories based on current handling capability:

Category A - Standard Current (100 mA): BC547B, BC547BBU, BC547CBU, BC550CBU, and 2N5232A PBFREE. These devices maintain the 100 mA collector current rating and are suitable for direct replacement in applications requiring standard signal-level switching and amplification.

Category B - Enhanced Current (1 A and above): ZTX450 and ZTX690B. These devices exceed the 100 mA specification and are suitable for applications requiring higher current handling or where design margin improvement is beneficial. These parts use E-Line packaging, which is mechanically compatible with TO-92 footprints.

Parameter Comparison

Parameter	BC237C	BC547B	BC547BBU	BC547CBU	BC550CBU	2N5232A PBFREE	ZTX450	ZTX690B
Transistor Type	NPN	NPN	NPN	NPN	NPN	NPN	NPN	NPN
Voltage - Collector Emitter Breakdown (Max) [V]	45	45	45	45	45	50	45	45
Current - Collector (Ic) (Max) [mA]	100	100	100	100	100	100	1000	2000
Vce Saturation (Max) @ Ib, Ic [mV]	600 @ 5, 100	600 @ 5, 100	600 @ 5, 100	600 @ 5, 100	600 @ 5, 100	125 @ 1, 10	250 @ 15, 150	500 @ 5, 1000
Current - Collector Cutoff (Max) [nA]	15	15	15	15	15	30	100	100
DC Current Gain (hFE) (Min) @ Ic, Vce	380 @ 2, 5	200 @ 2, 5	200 @ 2, 5	420 @ 2, 5	420 @ 2, 5	250 @ 2, 5	100 @ 150, 10	400 @ 1000, 2
Power - Max [mW]	350	500	500	500	500	625	1000	1000
Frequency - Transition [MHz]	200	300	300	300	300	—	150	150
Operating Temperature [°C]	-55 to 150	-55 to 150	—	—	—	-65 to 150	-55 to 200	-55 to 200
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	TO-226-3, TO-92-3	TO-226-3, TO-92-3	TO-226-3, TO-92-3	TO-226-3, TO-92-3	TO-226-3, TO-92-3	TO-226-3, TO-92-3	E-Line-3	E-Line-3

Engineering Selection Recommendations

For Direct Replacement (Standard Current Applications):

BC547CBU (Fairchild Semiconductor) and BC550CBU (onsemi) are the preferred substitutes for the BC237C in applications requiring 100 mA collector current. Both devices are active products with ROHS3 compliance and REACH unaffected status. BC547CBU offers a DC current gain minimum of 420 @ 2 mA, 5 V, exceeding the BC237C specification of 380, providing improved gain margin. BC550CBU provides identical electrical performance with onsemi manufacturing continuity.

BC547B (Diotec Semiconductor) and BC547BBU (onsemi) are functionally equivalent alternatives. BC547B is an active product available in cut tape packaging. BC547BBU is an active onsemi product with ROHS3 compliance.

2N5232A PBFREE (Central Semiconductor Corp) is an active substitute with higher voltage rating (50 V) and power dissipation (625 mW), suitable for applications requiring additional design margin. This device is ROHS3 compliant and operates across an extended temperature range (-65°C to 150°C).

For Enhanced Current Applications:

ZTX450 (Diodes Incorporated) is an active product rated for 1 A collector current with 45 V breakdown voltage. This device is suitable for applications where the BC237C current rating is insufficient or where higher current capability provides design flexibility. ZTX450 operates across -55°C to 200°C and is ROHS3 compliant.

ZTX690B (Diodes Incorporated) is an active product rated for 2 A collector current with identical voltage and temperature specifications as ZTX450. This device is appropriate for high-current switching applications where the BC237C cannot meet current requirements.

Compliance and Availability:

All recommended substitutes are active products with current manufacturing status. BC547CBU, BC550CBU, BC547BBU, 2N5232A PBFREE, ZTX450, and ZTX690B are ROHS3 compliant. All substitute parts are REACH unaffected and carry EAR99 ECCN classification, matching the BC237C regulatory profile.

Frequently Asked Questions (FAQ)

Q: Can BC547CBU directly replace BC237C in all applications?

A: BC547CBU meets or exceeds all electrical parameters of the BC237C: 45 V breakdown voltage, 100 mA collector current, 600 mV saturation voltage, and 300 MHz transition frequency. The device is packaged in TO-92-3 (TO-226-3), which is mechanically compatible with BC237C footprints. BC547CBU is an active product with ROHS3 compliance, making it suitable for direct replacement in new designs and field service applications.

Q: What is the difference between BC547B and BC547BBU?

A: BC547B is manufactured by Diotec Semiconductor and supplied in cut tape packaging. BC547BBU is manufactured by onsemi and supplied in bulk packaging. Both devices are electrically identical with 45 V breakdown voltage, 100 mA collector current, and 300 MHz transition frequency. Selection between these variants depends on packaging requirements and supplier preference.

Q: When should ZTX450 or ZTX690B be used instead of BC547 variants?

A: ZTX450 and ZTX690B are appropriate when the application requires collector current exceeding 100 mA. ZTX450 is rated for 1 A maximum collector current, and ZTX690B is rated for 2 A. Both devices maintain 45 V breakdown voltage and are packaged in E-Line configuration, which is mechanically compatible with TO-92 footprints. These devices are suitable for power switching applications where the BC237C current rating is insufficient.

Q: Is 2N5232A PBFREE compatible with BC237C?

A: 2N5232A PBFREE is electrically compatible with BC237C for applications requiring 100 mA collector current. This device offers higher voltage rating (50 V versus 45 V) and higher power dissipation (625 mW versus 350 mW), providing additional design margin. The extended operating temperature range (-65°C to 150°C) accommodates applications with lower temperature requirements. 2N5232A PBFREE is ROHS3 compliant and REACH unaffected.

Q: Are there package compatibility concerns when substituting BC237C?

A: BC237C is packaged in TO-92-3 (TO-226-3) long body configuration. All BC547 variants and 2N5232A PBFREE are packaged in TO-92-3 (TO-226-3) with formed leads, providing direct mechanical compatibility. ZTX450 and ZTX690B are packaged in E-Line-3 configuration, which is mechanically compatible with TO-92 footprints and PCB layouts. No package adapter or layout modification is required for any recommended substitute.

Q: What is the significance of DC current gain (hFE) differences among substitutes?

A: BC237C specifies minimum hFE of 380 @ 2 mA, 5 V. BC547CBU and BC550CBU specify minimum hFE of 420 @ 2 mA, 5 V, providing higher gain. BC547B and BC547BBU specify minimum hFE of 200 @ 2 mA, 5 V, which is lower than BC237C. In applications where gain is critical, BC547CBU or BC550CBU are preferred. In applications where gain margin is not limiting, BC547B or BC547BBU are acceptable. ZTX450 and ZTX690B specify hFE at higher collector currents (100 @ 150 mA and 400 @ 1 A, respectively) due to their higher current ratings.

Q: Are all substitute parts RoHS compliant?

A: BC547CBU, BC550CBU, BC547BBU, 2N5232A PBFREE, ZTX450, and ZTX690B are all ROHS3 compliant. The original BC237C is RoHS non-compliant. All substitutes meet current environmental and regulatory requirements for new product designs and manufacturing.

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

A: BC237C, BC547B, BC547BBU, and BC547CBU operate across -55°C to 150°C. 2N5232A PBFREE operates across -65°C to 150°C, providing extended low-temperature capability. ZTX450 and ZTX690B operate across -55°C to 200°C, providing extended high-temperature capability. Selection depends on application temperature requirements.

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