BC327,126 PNP Bipolar Junction Transistor Equivalent & Substitute Parts

Part Overview

The BC327,126 is a PNP bipolar junction transistor manufactured by NXP USA Inc., rated for 45V collector-emitter breakdown voltage and 500mA maximum collector current. This device is classified as obsolete, necessitating identification of active substitute components for new designs and production continuity. The BC327,126 is packaged in TO-92-3 (TO-226AA) through-hole configuration with 625mW maximum power dissipation and 80MHz transition frequency. Substitute parts must maintain electrical compatibility within the specified parameter ranges while offering active product status and current manufacturing availability.

Key Parameters

Parameter	Value	Unit	Condition
Transistor Type	PNP
Collector-Emitter Breakdown Voltage (Max)	45	V
Collector Current (Max)	500	mA
Power Dissipation (Max)	625	mW
Transition Frequency	80	MHz
DC Current Gain (hFE Min)	100		@ 100mA, 1V
Vce Saturation (Max)	700	mV	@ 50mA, 500mA
Package Type	TO-92-3		Through Hole
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitute parts for the BC327,126 are classified into two functional groups based on electrical parameter compatibility:

Group 1: Lower Current Substitutes (200mA Maximum) Parts 2N3906TA, 2N3906TAR, and 2N3906TF operate at reduced collector current (200mA) compared to the BC327,126 (500mA). These substitutes are suitable for applications where the circuit design permits lower current handling. All Group 1 parts feature 40V collector-emitter breakdown voltage, which is lower than the BC327,126 specification of 45V.

Group 2: Higher Current Substitutes (600-800mA Maximum) Parts 2N4403TA, 2N4403TAR, 2N4403TF, 2N4403TFR, BC32725TA, and BC32740TA support collector currents of 600mA or 800mA, exceeding the BC327,126 specification of 500mA. These parts maintain or exceed the 45V collector-emitter breakdown voltage requirement. BC32725TA and BC32740TA specifically match the 45V voltage rating of the original part.

Substitution Criteria: The following parameters determine valid substitution:

Transistor type must remain PNP
Collector-emitter breakdown voltage must equal or exceed circuit requirements
Maximum collector current must equal or exceed circuit requirements
Power dissipation must equal or exceed circuit requirements (625mW for all candidates)
Package type must be TO-92-3 through-hole configuration
All substitute parts must have active product status

Parameter Comparison

Part Number	Manufacturer	Ic Max (mA)	Vce Breakdown (V)	Power Max (mW)	Frequency (MHz)	hFE Min @ Ic, Vce	Vce Sat Max (mV)	Status
BC327,126	NXP USA Inc.	500	45	625	80	100 @ 100mA, 1V	700 @ 50mA, 500mA	Obsolete
2N3906TA	Fairchild Semiconductor	200	40	625	250	100 @ 10mA, 1V	400 @ 5mA, 50mA	Active
2N3906TAR	onsemi	200	40	625	250	100 @ 10mA, 1V	400 @ 5mA, 50mA	Active
2N3906TF	onsemi	200	40	625	250	100 @ 10mA, 1V	400 @ 5mA, 50mA	Active
2N3906TFR	onsemi	200	40	625	250	100 @ 10mA, 1V	400 @ 5mA, 50mA	Active
2N4403TA	onsemi	600	40	625	200	100 @ 150mA, 2V	750 @ 50mA, 500mA	Active
2N4403TAR	onsemi	600	40	625	200	100 @ 150mA, 2V	750 @ 50mA, 500mA	Active
2N4403TF	onsemi	600	40	625	200	100 @ 150mA, 2V	750 @ 50mA, 500mA	Active
2N4403TFR	onsemi	600	40	625	200	100 @ 150mA, 2V	750 @ 50mA, 500mA	Active
BC32725TA	onsemi	800	45	625	100	160 @ 100mA, 1V	700 @ 50mA, 500mA	Active
BC32740TA	onsemi	800	45	625	100	250 @ 100mA, 1V	700 @ 50mA, 500mA	Active

Engineering Selection Recommendations

Primary Substitutes (Recommended for Direct Replacement):

BC32725TA and BC32740TA are the preferred substitutes for the BC327,126. Both parts maintain the 45V collector-emitter breakdown voltage specification and provide enhanced collector current capability (800mA versus 500mA). These parts are manufactured by onsemi with active product status, ROHS3 compliance, and REACH unaffected certification. BC32725TA offers 160mA minimum hFE at 100mA and 1V, while BC32740TA provides 250mA minimum hFE under identical conditions. Both parts feature identical saturation voltage characteristics (700mV @ 50mA, 500mA) and operating temperature range (150°C maximum junction temperature) as the original BC327,126.

Secondary Substitutes (Current-Limited Applications):

The 2N4403 series (2N4403TA, 2N4403TAR, 2N4403TF, 2N4403TFR) provides 600mA collector current capability with active product status and full compliance certifications. These parts operate at 40V collector-emitter breakdown voltage, which is 5V lower than the BC327,126 specification. Selection of 2N4403 variants is appropriate for circuits where the maximum supply voltage does not exceed 40V.

Lower Current Alternatives (Reduced Capability):

The 2N3906 series (2N3906TA, 2N3906TAR, 2N3906TF, 2N3906TFR) is limited to 200mA maximum collector current and 40V breakdown voltage. These parts are suitable only for low-current signal amplification applications and do not provide functional equivalence for the BC327,126 in higher-current switching or driver applications.

Compliance and Availability:

All recommended substitute parts carry ROHS3 compliance and REACH unaffected status. Packaging variants (Cut Tape, Bulk) are available across multiple manufacturers (onsemi, Fairchild Semiconductor). Current inventory levels support production requirements, with BC32725TA maintaining 45,300 units and BC32740TA maintaining 4,892 units in stock.

Frequently Asked Questions (FAQ)

Q1: Can the 2N3906 series directly replace the BC327,126?

The 2N3906 series operates at 200mA maximum collector current, which is 60% lower than the BC327,126 specification of 500mA. Direct replacement is not recommended for applications requiring the full 500mA current capability. The 2N3906 series is suitable only for low-current signal amplification circuits where collector current does not exceed 200mA.

Q2: What is the difference between BC32725TA and BC32740TA?

Both parts are electrically identical except for DC current gain (hFE) specification. BC32725TA guarantees minimum hFE of 160 at 100mA and 1V, while BC32740TA guarantees minimum hFE of 250 under identical conditions. Selection depends on circuit requirements for current gain. Both parts maintain identical maximum ratings, saturation characteristics, and operating temperature specifications.

Q3: Why do the 2N4403 series parts specify 40V breakdown voltage instead of 45V?

The 2N4403 series is rated for 40V maximum collector-emitter breakdown voltage, which is 5V lower than the BC327,126 specification of 45V. These parts are suitable for circuits where the maximum supply voltage does not exceed 40V. For circuits requiring 45V operation, BC32725TA or BC32740TA must be selected.

Q4: Are all substitute parts available in TO-92-3 through-hole packaging?

All substitute parts listed are manufactured in TO-92-3 (TO-226AA) through-hole configuration with formed leads. Package compatibility is maintained across all recommended substitutes. Packaging variants (Cut Tape, Bulk) differ only in delivery format and do not affect electrical or mechanical specifications.

Q5: What is the significance of the "TAR" and "TF" suffixes in part numbers?

The suffix designations indicate packaging and tape format specifications. "TA" indicates standard tape format, "TAR" indicates tape with reel, and "TF" indicates alternative tape format. These suffixes do not affect electrical performance or specifications. Selection among variants depends on procurement and assembly equipment compatibility.

Q6: Do all substitute parts meet RoHS and REACH compliance requirements?

All active substitute parts (2N3906 series, 2N4403 series, BC32725TA, BC32740TA) carry ROHS3 compliance certification. REACH status is unaffected for all parts. The original BC327,126 also carries ROHS3 compliance. Compliance certifications are maintained across all recommended substitutes.

Q7: What is the operating temperature range for substitute parts?

The BC327,126 specifies maximum junction temperature of 150°C. The 2N3906 series specifies operating temperature range of -55°C to 150°C. The 2N4403 series and BC327 variants specify operating temperature range of -55°C to 150°C. All parts maintain compatible thermal specifications for standard industrial applications.

Q8: Can substitute parts be used interchangeably in existing PCB designs?

All substitute parts maintain identical TO-92-3 through-hole pin configuration and lead spacing. Physical PCB compatibility is maintained. Electrical compatibility depends on circuit current and voltage requirements. BC32725TA and BC32740TA provide direct functional replacement. Lower-current alternatives (2N3906, 2N4403 at 40V) require circuit analysis to confirm compatibility with design specifications.

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