RN1105,LF(CT Pre-Biased NPN Transistor Equivalent & Substitute Parts

Part Overview

The RN1105,LF(CT is an active pre-biased NPN bipolar junction transistor (BJT) manufactured by Toshiba Semiconductor and Storage. This surface mount device operates at 50 V collector-emitter breakdown voltage with a maximum collector current of 100 mA and is designed for general-purpose switching and amplification applications. The part is supplied in Tape & Reel packaging with SC-75 (SOT-416) package configuration and maintains ROHS3 compliance with unlimited moisture sensitivity rating (MSL 1).

Equivalent and substitute parts are identified when component availability is limited, supply chain disruptions occur, or design flexibility is required while maintaining electrical and mechanical compatibility within specified parameter tolerances.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN - Pre-Biased	—
Current - Collector (Ic) (Max)	100	mA
Voltage - Collector Emitter Breakdown (Max)	50	V
Resistor - Base (R1)	2.2	kOhms
Resistor - Emitter Base (R2)	47	kOhms
DC Current Gain (hFE) (Min)	80	—
Vce Saturation (Max)	300	mV
Current - Collector Cutoff (Max)	500	nA
Frequency - Transition	250	MHz
Power - Max	100	mW
Mounting Type	Surface Mount	—
Package / Case	SC-75, SOT-416	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution eligibility for the RN1105,LF(CT is determined by strict alignment of the following critical parameters:

Electrical Compatibility Requirements:

Transistor type classification: NPN - Pre-Biased
Maximum collector current: 100 mA
Collector-emitter breakdown voltage: 50 V
Base resistor (R1): 2.2 kOhms
Emitter-base resistor (R2): 47 kOhms (where specified)
DC current gain minimum (hFE): 80
Collector cutoff current: 500 nA maximum
RoHS3 compliance and MSL 1 rating

Mechanical Compatibility Requirements:

Surface mount mounting type
Package configuration: SC-75 (SOT-416) or SOT-523 (with functional equivalence)

Substitute parts must satisfy all electrical parameters within the specified tolerances and maintain equivalent or superior performance characteristics. Package variations are acceptable when pin configuration and footprint compatibility are preserved.

Parameter Comparison

Parameter	RN1105,LF(CT (Toshiba)	DTC123JE-TP (Micro Commercial Co)	DTC123JET1G (onsemi)	NSVDTC123JET1G (onsemi)
Transistor Type	NPN - Pre-Biased	NPN - Pre-Biased	NPN - Pre-Biased	NPN - Pre-Biased
Current - Collector (Ic) (Max)	100 mA	100 mA	100 mA	100 mA
Voltage - Collector Emitter Breakdown (Max)	50 V	50 V	50 V	50 V
Resistor - Base (R1)	2.2 kOhms	2.2 kOhms	2.2 kOhms	2.2 kOhms
Resistor - Emitter Base (R2)	47 kOhms	Not specified	47 kOhms	47 kOhms
DC Current Gain (hFE) (Min)	80 @ 10mA, 5V	80 @ 5mA, 10V	80 @ 5mA, 10V	80 @ 5mA, 10V
Vce Saturation (Max)	300 mV @ 250µA, 5mA	250 mV @ 300µA, 10mA	250 mV @ 1mA, 10mA	250 mV @ 1mA, 10mA
Current - Collector Cutoff (Max)	500 nA	500 nA	500 nA	500 nA
Power - Max	100 mW	300 mW	200 mW	200 mW
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Package / Case	SC-75, SOT-416	SOT-523	SC-75, SOT-416	SC-75, SOT-416
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

Primary Substitutes (Highest Compatibility):

DTC123JET1G (onsemi) and NSVDTC123JET1G (onsemi) are direct functional equivalents to the RN1105,LF(CT. Both parts maintain identical package configuration (SC-75, SOT-416), matching pin assignments and PCB footprint requirements. These substitutes satisfy all critical electrical parameters including collector current, breakdown voltage, base and emitter-base resistor values, and current gain specifications. Both are ROHS3 compliant with MSL 1 rating. The onsemi variants demonstrate superior power dissipation capability (200 mW versus 100 mW) and improved saturation voltage characteristics, providing enhanced performance margins in switching applications.

Secondary Substitute (Package Variation):

DTC123JE-TP (Micro Commercial Co) operates within all specified electrical parameters but utilizes SOT-523 package configuration rather than SC-75 (SOT-416). This package variant requires PCB layout modification and is suitable only when design flexibility permits footprint changes. The DTC123JE-TP offers the highest power dissipation rating (300 mW) among all listed substitutes. The emitter-base resistor (R2) specification is not provided for this variant; verification of circuit compatibility is necessary when this parameter is critical to application performance.

Compliance and Availability:

All substitute parts maintain active product status and ROHS3 compliance. onsemi variants (DTC123JET1G and NSVDTC123JET1G) demonstrate significantly higher inventory availability (260,400 and 6,732 units respectively) compared to the primary part (1,070 units), supporting supply chain continuity and lead time reduction.

Frequently Asked Questions (FAQ)

Q: Can DTC123JE-TP be used as a direct replacement for RN1105,LF(CT on existing PCBs?

A: DTC123JE-TP is electrically compatible but uses SOT-523 package instead of SC-75 (SOT-416). Direct PCB substitution is not possible without layout modification. The different package footprint requires redesign of the component placement area.

Q: What is the difference between DTC123JET1G and NSVDTC123JET1G?

A: Both parts are manufactured by onsemi, share identical electrical specifications, package configuration (SC-75, SOT-416), and compliance ratings. The primary distinction is the part number prefix (DTC123 versus NSVDTC123), which may reflect different manufacturing lines or distribution channels. Electrical and mechanical performance are equivalent.

Q: Are the saturation voltage differences between RN1105,LF(CT and substitute parts significant?

A: The RN1105,LF(CT specifies 300 mV maximum saturation voltage at 250 µA base current and 5 mA collector current. Substitute parts specify 250 mV maximum at different test conditions (300 µA base, 10 mA collector for DTC123JE-TP; 1 mA base, 10 mA collector for onsemi variants). These differences reflect different measurement conditions rather than incompatibility. All parts meet saturation requirements for standard switching applications.

Q: Why is the emitter-base resistor (R2) not specified for DTC123JE-TP?

A: The DTC123JE-TP datasheet provided does not include R2 specification. When this parameter is critical to circuit function, DTC123JET1G or NSVDTC123JET1G are preferred substitutes, as both specify R2 = 47 kOhms matching the original RN1105,LF(CT.

Q: Can I use a substitute part with higher power dissipation rating?

A: Yes. DTC123JE-TP (300 mW) and DTC123JET1G/NSVDTC123JET1G (200 mW) all exceed the original 100 mW rating. Higher power dissipation capability provides additional thermal margin and does not compromise circuit function when electrical parameters remain within specification.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All listed substitute parts (DTC123JE-TP, DTC123JET1G, NSVDTC123JET1G) maintain ROHS3 compliance and MSL 1 (unlimited) moisture sensitivity rating, matching the original RN1105,LF(CT specifications.

Q: Which substitute offers the best supply availability?

A: DTC123JET1G (onsemi) provides the highest inventory level at 260,400 units in stock, followed by NSVDTC123JET1G at 6,732 units. Both onsemi variants significantly exceed the original part's 1,070-unit inventory, supporting extended lead time reduction and supply chain reliability.

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