TIP31B PBFREE Equivalent & Substitute Parts

Part Overview

The TIP31B PBFREE is an NPN bipolar junction transistor manufactured by Central Semiconductor Corp, designed for general-purpose switching and amplification applications. This device features a maximum collector current of 3 A, collector-emitter breakdown voltage of 80 V, and maximum power dissipation of 40 W in a Through Hole TO-220-3 package. The TIP31B PBFREE is classified as obsolete, making identification of equivalent substitute parts essential for ongoing design support and component procurement. Equivalent alternatives maintain the same electrical performance envelope and package form factor while ensuring design continuity.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Current - Collector (Ic) Max	3	A
Voltage - Collector Emitter Breakdown (Max)	80	V
Vce Saturation (Max) @ Ib, Ic	1.2 V @ 375 mA, 3 A	V
Current - Collector Cutoff (Max)	300	µA
Power - Max	40	W
Frequency - Transition	3	MHz
Operating Temperature Range	−65 to 150	°C
Package / Case	TO-220-3	—
Mounting Type	Through Hole	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the TIP31B PBFREE is determined by strict equivalence across the following critical parameters:

Electrical Equivalence Criteria:

Transistor polarity: NPN
Maximum collector current: 3 A
Collector-emitter breakdown voltage: 80 V
Saturation voltage: 1.2 V @ 375 mA, 3 A
Collector cutoff current: 300 µA
Transition frequency: 3 MHz

Mechanical Equivalence Criteria:

Package type: TO-220-3 Through Hole
Mounting configuration: Through Hole

Compliance Equivalence Criteria:

RoHS3 compliance
ECCN classification: EAR99

The TIP31B manufactured by Fairchild Semiconductor qualifies as a parametric equivalent. Both devices share identical collector current, breakdown voltage, saturation voltage, cutoff current, transition frequency, and package configuration. Both are RoHS3 compliant and carry the same ECCN classification. Differences in maximum power dissipation (40 W vs. 2 W) and DC current gain specifications do not preclude substitution when the application thermal and gain requirements fall within the Fairchild device specifications.

Parameter Comparison

Parameter	Central Semiconductor TIP31B PBFREE	Fairchild Semiconductor TIP31B	Match Status
Transistor Type	NPN	NPN	Equivalent
Current - Collector (Ic) Max	3 A	3 A	Equivalent
Voltage - Collector Emitter Breakdown (Max)	80 V	80 V	Equivalent
Vce Saturation (Max) @ Ib, Ic	1.2 V @ 375 mA, 3 A	1.2 V @ 375 mA, 3 A	Equivalent
Current - Collector Cutoff (Max)	300 µA	300 µA	Equivalent
Frequency - Transition	3 MHz	3 MHz	Equivalent
Operating Temperature Range	−65 to 150 °C	−65 to 150 °C	Equivalent
Package / Case	TO-220-3	TO-220-3	Equivalent
Mounting Type	Through Hole	Through Hole	Equivalent
Power - Max	40 W	2 W	Fairchild rated lower
DC Current Gain (hFE) Min @ Ic, Vce	25 @ 1 A, 4 V	10 @ 3 A, 4 V	Different test conditions
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	Equivalent

Engineering Selection Recommendations

Primary Substitute: Fairchild Semiconductor TIP31B

The Fairchild Semiconductor TIP31B is a direct parametric equivalent for the Central Semiconductor TIP31B PBFREE across all critical electrical and mechanical specifications. Both devices are obsolete, RoHS3 compliant, and share identical package configuration and thermal operating range.

Selection Considerations:

Power Dissipation: The Fairchild device is rated at 2 W maximum power dissipation compared to 40 W for the Central Semiconductor part. Applications requiring sustained power dissipation above 2 W must employ external heat management or select alternative devices with higher power ratings.
Compliance Status: Both devices maintain ROHS3 compliance and EAR99 ECCN classification, ensuring regulatory equivalence for procurement and export purposes.
Availability: The Fairchild Semiconductor TIP31B is available in higher inventory quantities (3173 pcs) compared to the Central Semiconductor variant (842 pcs), supporting extended production runs and supply chain continuity.
Package Compatibility: Both devices utilize identical TO-220-3 Through Hole packaging, permitting direct board-level substitution without PCB redesign.

Frequently Asked Questions (FAQ)

Q: Can the Fairchild Semiconductor TIP31B directly replace the Central Semiconductor TIP31B PBFREE in existing designs?

A: Yes, for applications where power dissipation does not exceed 2 W. The devices are electrically and mechanically equivalent across all specified parameters. Applications requiring higher power dissipation must implement external thermal management or select alternative devices.

Q: What is the significance of the different power ratings (40 W vs. 2 W)?

A: Power rating reflects the maximum continuous power dissipation the device can sustain under specified thermal conditions. The Fairchild device's lower rating indicates reduced thermal capacity. Circuit designs must ensure actual power dissipation remains within the selected device's specification.

Q: Are there differences in DC current gain between these devices?

A: Yes. The Central Semiconductor part specifies minimum hFE of 25 @ 1 A, 4 V, while the Fairchild part specifies minimum hFE of 10 @ 3 A, 4 V. These are measured at different operating points. Designs relying on specific gain characteristics at particular collector currents must verify compatibility with the selected device's gain specification.

Q: Do both devices require identical PCB footprints?

A: Yes. Both devices use TO-220-3 Through Hole packaging with identical pin configuration and spacing, permitting direct PCB substitution.

Q: Are there supply chain or availability advantages to selecting the Fairchild device?

A: The Fairchild Semiconductor TIP31B maintains higher current inventory levels, potentially offering improved lead times and supply continuity for production requirements.

Q: What compliance certifications apply to both devices?

A: Both devices are RoHS3 compliant and classified under ECCN EAR99, meeting current regulatory requirements for electronics manufacturing and export.

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