2N4403_D81Z Equivalent & Substitute Parts

Part Overview

The 2N4403_D81Z is a PNP bipolar junction transistor manufactured by onsemi, rated for 40 V collector-emitter breakdown voltage and 600 mA maximum collector current. This device is packaged in TO-92-3 through-hole configuration and operates across a temperature range of -55°C to 150°C. The part is classified as obsolete, making identification of equivalent and substitute components necessary for ongoing design support, maintenance, and production continuity.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP	—
Voltage - Collector Emitter Breakdown (Max)	40	V
Current - Collector (Ic) (Max)	600	mA
Vce Saturation (Max) @ Ib, Ic	750 mV @ 50 mA, 500 mA	—
DC Current Gain (hFE) (Min) @ Ic, Vce	100 @ 150 mA, 2 V	—
Power - Max	625	mW
Frequency - Transition	200	MHz
Operating Temperature	-55 to 150	°C
Mounting Type	Through Hole	—
Package / Case	TO-92-3 (TO-226AA)	—

Substitute Part Grouping Explanation

Substitution of the 2N4403_D81Z is determined by electrical and mechanical parameter compatibility. The following criteria establish valid substitute relationships:

Primary Substitution Criteria:

Transistor Type: PNP
Voltage - Collector Emitter Breakdown (Max): ≥ 40 V
Current - Collector (Ic) (Max): ≥ 600 mA
Vce Saturation (Max) @ Ib, Ic: ≤ 750 mV @ 50 mA, 500 mA
DC Current Gain (hFE) (Min) @ Ic, Vce: ≥ 100 @ 150 mA, 2 V
Power - Max: ≥ 625 mW
Frequency - Transition: ≥ 200 MHz
Operating Temperature: -55°C to 150°C minimum
Mounting Type: Through Hole
Package / Case: TO-92-3 compatible

Direct Substitutes meet all primary criteria with identical electrical specifications and package compatibility.

Similar Substitutes meet core electrical requirements but may have variations in secondary parameters such as maximum power dissipation, transition frequency, or operating temperature range. These parts are functionally equivalent within the specified application envelope.

Parameter Comparison

Parameter	2N4403_D81Z (Main)	2N4403BU	2N4403TA	2N4403TF	2N4403-AP	ZTX549STZ
Manufacturer	onsemi	Fairchild Semiconductor	onsemi	onsemi	Micro Commercial Co	Diodes Incorporated
Product Status	Obsolete	Active	Active	Active	Obsolete	Active
Transistor Type	PNP	PNP	PNP	PNP	PNP	PNP
Voltage - Collector Emitter Breakdown (Max)	40 V	40 V	40 V	40 V	40 V	30 V
Current - Collector (Ic) (Max)	600 mA	600 mA	600 mA	600 mA	600 mA	1 A
Vce Saturation (Max) @ Ib, Ic	750 mV @ 50 mA, 500 mA	750 mV @ 50 mA, 500 mA	750 mV @ 50 mA, 500 mA	750 mV @ 50 mA, 500 mA	750 mV @ 50 mA, 500 mA	750 mV @ 200 mA, 2 A
DC Current Gain (hFE) (Min) @ Ic, Vce	100 @ 150 mA, 2 V	100 @ 150 mA, 2 V	100 @ 150 mA, 2 V	100 @ 150 mA, 2 V	100 @ 150 mA, 2 V	100 @ 500 mA, 2 V
Power - Max	625 mW	625 mW	625 mW	625 mW	600 mW	1 W
Frequency - Transition	200 MHz	200 MHz	200 MHz	200 MHz	200 MHz	100 MHz
Operating Temperature	-55 to 150 °C	-55 to 150 °C	-55 to 150 °C	-55 to 150 °C	-55 to 150 °C	-55 to 200 °C
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	TO-92-3	TO-92-3	TO-92-3	TO-92-3	TO-92	E-Line (TO-92 compatible)
RoHS Status	Not specified	Not specified	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

Direct Substitutes (Recommended for Replacement):

The 2N4403BU, 2N4403TA, and 2N4403TF are direct electrical and mechanical equivalents to the 2N4403_D81Z. These parts share identical electrical specifications across all critical parameters and are housed in compatible TO-92-3 packages. Selection among these three should be based on product availability and supply chain considerations:

2N4403BU (Fairchild Semiconductor): Active product status with high inventory availability (69,662 units). Supplied in bulk packaging.
2N4403TA (onsemi): Active product status with substantial inventory (60,100 units). Supplied in cut tape. RoHS3 compliant.
2N4403TF (onsemi): Active product status with limited inventory (1,500 units). Supplied in cut tape. RoHS3 compliant.

Similar Substitute (Application-Dependent):

The 2N4403-AP (Micro Commercial Co) is functionally equivalent with identical electrical specifications but is classified as obsolete. This part should be considered only when direct substitutes are unavailable and application requirements do not demand long-term supply assurance.

The ZTX549STZ (Diodes Incorporated) is a similar substitute with enhanced electrical performance characteristics. This part exceeds the 2N4403_D81Z specifications in collector current (1 A vs. 600 mA), power dissipation (1 W vs. 625 mW), and operating temperature range (-55°C to 200°C vs. -55°C to 150°C). However, the ZTX549STZ has reduced collector-emitter breakdown voltage (30 V vs. 40 V) and transition frequency (100 MHz vs. 200 MHz). The ZTX549STZ is suitable for applications where the lower voltage rating and reduced frequency response are acceptable and where the enhanced current and thermal capabilities provide design margin.

Frequently Asked Questions (FAQ)

Q: Can the 2N4403BU directly replace the 2N4403_D81Z without circuit modification?

A: Yes. The 2N4403BU is a direct electrical and mechanical equivalent. All critical parameters—collector-emitter breakdown voltage, maximum collector current, saturation voltage, current gain, power dissipation, and transition frequency—are identical. The TO-92-3 package is mechanically compatible with the original part.

Q: What is the difference between 2N4403TA and 2N4403TF?

A: Both parts are manufactured by onsemi and are electrically identical to the 2N4403_D81Z. The primary difference is inventory availability: 2N4403TA has 60,100 units in stock, while 2N4403TF has 1,500 units. Both are supplied in cut tape packaging and are RoHS3 compliant.

Q: Why does the ZTX549STZ have a lower collector-emitter breakdown voltage than the 2N4403_D81Z?

A: The ZTX549STZ is designed for different application requirements. While it provides enhanced current handling (1 A vs. 600 mA) and power dissipation (1 W vs. 625 mW), its 30 V breakdown voltage rating is lower than the 2N4403_D81Z's 40 V rating. Selection of the ZTX549STZ requires verification that the application's maximum collector-emitter voltage does not exceed 30 V.

Q: Is the 2N4403-AP suitable for new designs?

A: The 2N4403-AP is classified as obsolete and should not be selected for new designs. It is electrically equivalent to the 2N4403_D81Z but lacks long-term supply assurance. Use active products such as 2N4403BU, 2N4403TA, or 2N4403TF for new applications.

Q: Are all substitute parts RoHS3 compliant?

A: The 2N4403TA and 2N4403TF are explicitly RoHS3 compliant. The 2N4403BU compliance status is not specified in the provided data. The 2N4403-AP is RoHS3 compliant but is obsolete. The ZTX549STZ is RoHS3 compliant. Verify RoHS compliance requirements with the specific supplier for the 2N4403BU.

Q: Can the ZTX549STZ be used in applications requiring 40 V collector-emitter breakdown voltage?

A: No. The ZTX549STZ has a maximum collector-emitter breakdown voltage of 30 V, which is insufficient for applications requiring 40 V rating. Use 2N4403BU, 2N4403TA, or 2N4403TF for such applications.

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

A: TO-92-3 indicates a three-lead through-hole package with formed leads. This package is mechanically and electrically compatible across 2N4403BU, 2N4403TA, and 2N4403TF. The ZTX549STZ uses an E-Line package, which is physically similar but may require verification of lead spacing and PCB hole positioning for direct substitution.

Q: How should I select between 2N4403BU, 2N4403TA, and 2N4403TF?

A: All three parts are direct electrical equivalents. Selection should be based on: (1) inventory availability and lead time requirements, (2) packaging preference (bulk vs. cut tape), (3) RoHS compliance certification needs, and (4) supplier relationship and pricing. For new designs, 2N4403TA or 2N4403TF are preferred due to explicit RoHS3 compliance documentation.

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