FJX3003RTF Equivalent & Substitute Parts

Part Overview

The FJX3003RTF is a pre-biased NPN bipolar junction transistor (BJT) manufactured by onsemi, designed for surface mount applications in the SOT-323 package. This component operates at 50 V collector-emitter breakdown voltage with a maximum collector current of 100 mA and 250 MHz transition frequency. The device integrates internal base and emitter-base resistors (22 kOhms each) for simplified circuit design.

The FJX3003RTF is classified as obsolete. Substitute components are necessary to maintain design continuity and ensure ongoing component availability for new production and field replacements.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN - Pre-Biased	—
Voltage - Collector Emitter Breakdown (Max)	50	V
Current - Collector (Ic) (Max)	100	mA
Resistor - Base (R1)	22	kOhms
Resistor - Emitter Base (R2)	22	kOhms
DC Current Gain (hFE) (Min) @ Ic, Vce	56 @ 5mA, 5V	—
Vce Saturation (Max) @ Ib, Ic	300mV @ 500µA, 10mA	—
Frequency - Transition	250	MHz
Power - Max	200	mW
Package / Case	SC-70, SOT-323	—
Mounting Type	Surface Mount	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the FJX3003RTF is determined by strict equivalence across the following critical parameters:

Primary Substitution Criteria:

Transistor type: NPN pre-biased configuration
Voltage rating: 50 V collector-emitter breakdown (minimum)
Current rating: 100 mA collector current (minimum)
Internal resistor configuration: R1 and R2 values must match or be functionally equivalent
Package compatibility: SOT-323 or equivalent surface mount package
Transition frequency: 250 MHz (minimum)
Power dissipation: 200 mW (minimum)

Substitution Categories:

Direct Equivalents maintain identical electrical specifications and internal resistor values (R1 = 22 kOhms, R2 = 22 kOhms). These parts are pin-compatible and require no circuit modifications.

Similar Equivalents share the same voltage, current, and frequency ratings but may have different internal resistor configurations or slightly different saturation characteristics. These require circuit evaluation before substitution.

Functional Alternatives meet the core voltage and current requirements but operate in different package types (SOT-523) or have different resistor networks. Package changes require PCB layout modifications.

Upgraded Alternatives exceed the minimum specifications in areas such as DC current gain, saturation voltage, or compliance certifications (automotive grade, RoHS3). These provide enhanced performance and are suitable for applications requiring higher reliability standards.

Parameter Comparison

Part Number	Manufacturer	Ic (Max) mA	Vce(br) V	R1 kOhms	R2 kOhms	hFE @ 5mA, 5V	Vce Sat mV	Freq MHz	Power mW	Package	Status
FJX3003RTF	onsemi	100	50	22	22	56	300	250	200	SOT-323	Obsolete
MUN5212T1G	onsemi	100	50	22	2.2	60	250	—	202	SC-70-3	Active
SMUN5212T1G	onsemi	100	50	22	22	60	250	—	202	SC-70-3	Active
DDTC124GE-7-F	Diodes Inc.	100	50	—	22	56	300	250	150	SOT-523	Active
PDTC124TU,115	Nexperia	100	50	22	—	100	150	—	200	SOT-323	Active
DDTC124EUA-7-F	Diodes Inc.	100	50	22	22	56	300	250	200	SOT-323	Active
DDTC124GUA-7-F	Diodes Inc.	100	50	—	22	56	300	250	200	SOT-323	Active
DDTC124TE-7-F	Diodes Inc.	100	50	22	—	100	300	250	150	SOT-523	Active
DTC114EUAT106	Rohm Semi.	100	50	10	10	30	300	250	200	UMT3	Active
DTC115EUAT106	Rohm Semi.	20	50	100	100	82	300	250	200	UMT3	Active
DTC123EUAT106	Rohm Semi.	100	50	2.2	2.2	20	300	250	200	UMT3	Active

Engineering Selection Recommendations

Direct Substitution (No Circuit Modification Required):

SMUN5212T1G and DDTC124EUA-7-F are direct electrical equivalents to FJX3003RTF. Both maintain identical internal resistor networks (R1 = 22 kOhms, R2 = 22 kOhms), matching voltage and current ratings, and equivalent saturation characteristics. Both are active products with RoHS3 compliance and unlimited moisture sensitivity rating. SMUN5212T1G offers higher inventory availability (75,200 units). DDTC124EUA-7-F maintains the same SOT-323 package footprint.

Package-Compatible Substitution (PCB Layout Modification Required):

DDTC124GE-7-F and DDTC124TE-7-F operate in SOT-523 package format instead of SOT-323. Both maintain 50 V / 100 mA ratings and 250 MHz transition frequency. DDTC124GE-7-F includes only R2 (22 kOhms) resistor network. DDTC124TE-7-F includes R1 (22 kOhms) resistor. These substitutions require PCB redesign for the different package footprint.

Functional Alternatives with Resistor Network Differences:

MUN5212T1G differs in R2 value (2.2 kOhms versus 22 kOhms). This lower emitter-base resistance results in higher DC current gain (60 versus 56) and lower saturation voltage (250 mV versus 300 mV). Circuit performance evaluation is required before substitution.

PDTC124TU,115 (Nexperia) provides automotive-grade qualification (AEC-Q100) with enhanced DC current gain (100 @ 1mA, 5V) and superior saturation voltage (150 mV). This upgraded alternative is suitable for applications requiring automotive reliability standards.

Not Recommended for Direct Substitution:

DTC115EUAT106 operates at reduced maximum collector current (20 mA versus 100 mA) and is unsuitable for applications requiring full 100 mA current capability.

DTC114EUAT106 and DTC123EUAT106 feature different internal resistor networks (10 kOhms and 2.2 kOhms respectively) that alter circuit biasing characteristics and are not recommended without comprehensive circuit redesign.

Frequently Asked Questions (FAQ)

Q: Can SMUN5212T1G replace FJX3003RTF without circuit modifications?

A: Yes. SMUN5212T1G maintains identical internal resistor values (R1 = 22 kOhms, R2 = 22 kOhms), voltage rating (50 V), current rating (100 mA), and package type (SOT-323). The part is pin-compatible and electrically equivalent. Higher DC current gain (60 versus 56) and lower saturation voltage (250 mV versus 300 mV) represent improved performance characteristics within acceptable design margins.

Q: What is the difference between DDTC124EUA-7-F and DDTC124GUA-7-F?

A: DDTC124EUA-7-F includes both internal resistors (R1 = 22 kOhms, R2 = 22 kOhms). DDTC124GUA-7-F includes only the emitter-base resistor (R2 = 22 kOhms) without a base resistor. The absence of R1 in DDTC124GUA-7-F alters circuit biasing behavior and requires circuit evaluation before substitution.

Q: Why do some substitutes use SOT-523 package instead of SOT-323?

A: SOT-523 is a smaller surface mount package than SOT-323. While both are three-terminal packages suitable for pre-biased transistors, SOT-523 requires different PCB footprint and layout. Substitution with SOT-523 parts (DDTC124GE-7-F, DDTC124TE-7-F) necessitates PCB redesign and is not recommended for direct board-level replacement without layout modification.

Q: Is PDTC124TU,115 suitable for automotive applications?

A: Yes. PDTC124TU,115 carries AEC-Q100 automotive qualification and RoHS3 compliance. This part is designated as an upgrade alternative and provides enhanced performance characteristics including higher DC current gain (100 @ 1mA, 5V) and lower saturation voltage (150 mV @ 500µA, 10mA). It is suitable for applications requiring automotive-grade reliability standards.

Q: What does "R2-ONLY SERIES" mean for DDTC124GE-7-F?

A: The DDTC124GE-7-F designation indicates this device includes only the emitter-base resistor (R2 = 22 kOhms) without an integrated base resistor (R1). This configuration is used in applications where external base biasing is provided. Direct substitution for FJX3003RTF (which includes both R1 and R2) requires circuit modification.

Q: Can DTC115EUAT106 replace FJX3003RTF?

A: No. DTC115EUAT106 is rated for maximum collector current of 20 mA, which is insufficient for applications requiring the full 100 mA capability of FJX3003RTF. This part is not suitable as a substitute.

Q: What is the significance of the different R1 and R2 values in MUN5212T1G?

A: MUN5212T1G features R2 = 2.2 kOhms (versus 22 kOhms in FJX3003RTF). The lower emitter-base resistance increases the DC current gain and reduces saturation voltage. This results in faster switching response and lower power dissipation in saturation. Circuit evaluation is required to confirm compatibility with the original design.

Q: Are all substitute parts RoHS3 compliant?

A: All active substitute parts listed (SMUN5212T1G, DDTC124EUA-7-F, DDTC124GUA-7-F, DDTC124TE-7-F, PDTC124TU,115, DTC114EUAT106, DTC115EUAT106, DTC123EUAT106) carry RoHS3 compliance certification. The original FJX3003RTF (obsolete) does not specify RoHS status.

Q: What is the moisture sensitivity level for these components?

A: All listed components maintain MSL 1 (Unlimited) moisture sensitivity rating, indicating no special moisture control requirements during storage, handling, or assembly.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message