RN4901,LF Equivalent & Substitute Parts

Part Overview

The RN4901,LF is a pre-biased dual bipolar transistor (BJT) manufactured by Toshiba Semiconductor and Storage, configured as 1 NPN and 1 PNP transistor pair in a surface mount package. This component is classified as obsolete, which necessitates identification of active equivalent and substitute parts for ongoing design requirements and production continuity. The RN4901,LF operates at 50V maximum collector-emitter breakdown voltage with 100mA maximum collector current and 200mW power dissipation in a 6-TSSOP (US6) package.

Key Parameters

Parameter	Value	Unit
Transistor Type	1 NPN, 1 PNP - Pre-Biased (Dual)	—
Current - Collector (Ic) (Max)	100	mA
Voltage - Collector Emitter Breakdown (Max)	50	V
Resistor - Base (R1)	4.7	kOhms
Resistor - Emitter Base (R2)	4.7	kOhms
DC Current Gain (hFE) (Min) @ Ic, Vce	30 @ 10mA, 5V	—
Vce Saturation (Max) @ Ib, Ic	300	mV
Current - Collector Cutoff (Max)	500	nA
Power - Max	200	mW
Package / Case	6-TSSOP, SC-88, SOT-363	—
Mounting Type	Surface Mount	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the RN4901,LF is determined by the following critical parameters:

Transistor Configuration: The main part contains 1 NPN and 1 PNP pre-biased pair. Substitutes must maintain this dual-transistor configuration or provide functional equivalence through alternative configurations (such as dual NPN pairs) when circuit topology permits.
Electrical Ratings: Maximum collector current (100mA), collector-emitter breakdown voltage (50V), and base/emitter-base resistor values (4.7kOhms each) must be matched or exceeded.
Package Compatibility: All substitutes must use 6-TSSOP, SC-88, or SOT-363 surface mount packages to ensure PCB footprint compatibility.
Pre-Biasing Resistor Network: Internal base and emitter-base resistor values of 4.7kOhms must be present in substitute parts.
Product Status: Active substitutes are preferred over obsolete parts to ensure long-term availability and supply chain continuity.

Substitutes are grouped into two categories: direct equivalents (same NPN/PNP configuration) and functional alternatives (different transistor configurations with compatible electrical characteristics).

Parameter Comparison

Part Number	Manufacturer	Transistor Type	Ic (Max) mA	Vce Breakdown (Max) V	R1 / R2 kOhms	Power (Max) mW	Package	Product Status	RoHS Status
RN4901,LF	Toshiba	1 NPN, 1 PNP	100	50	4.7 / 4.7	200	6-TSSOP	Obsolete	—
RN4901,LF(CT	Toshiba	1 NPN, 1 PNP	100	50	4.7 / 4.7	200	6-TSSOP	Active	ROHS3 Compliant
PUMD15,115	Nexperia	1 NPN, 1 PNP	100	50	4.7 / 4.7	300	6-TSSOP	Active	ROHS3 Compliant
PUMD15,135	Nexperia	1 NPN, 1 PNP	100	50	4.7 / 4.7	300	6-TSSOP	Active	ROHS3 Compliant
PUMH15,115	Nexperia	2 NPN	100	50	4.7 / 4.7	300	6-TSSOP	Active	ROHS3 Compliant
MUN5232DW1T1G	onsemi	2 NPN	100	50	4.7 / 4.7	250	SOT-363	Active	ROHS3 Compliant
SMUN5232DW1T1G	onsemi	2 NPN	100	50	4.7 / 4.7	187	SOT-363	Active	ROHS3 Compliant

Engineering Selection Recommendations

Direct Equivalent (Preferred for Pin-Compatible Replacement)

RN4901,LF(CT is the direct equivalent of the obsolete RN4901,LF. This part maintains identical electrical specifications, transistor configuration (1 NPN, 1 PNP), and package format. The primary distinction is product status: RN4901,LF(CT is active and ROHS3 compliant, ensuring supply availability and regulatory compliance. This part is the recommended first choice for direct substitution.

Nexperia Automotive-Grade Alternatives

PUMD15,115 and PUMD15,135 are functionally equivalent to the RN4901,LF with identical transistor configuration and electrical ratings. Both parts feature higher power dissipation capability (300mW versus 200mW) and are qualified to AEC-Q100 automotive standards. These parts are suitable for applications requiring automotive-grade components. PUMD15,115 and PUMD15,135 are interchangeable with each other.

PUMH15,115 is a dual NPN configuration (2 NPN) rather than the mixed NPN/PNP configuration of the main part. This substitute is applicable only in circuits where dual NPN transistors satisfy the functional requirements. PUMH15,115 also carries AEC-Q100 automotive qualification.

onsemi Dual NPN Alternatives

MUN5232DW1T1G and SMUN5232DW1T1G are dual NPN pre-biased transistor pairs from onsemi. Both maintain the 50V/100mA electrical ratings and 4.7kOhms resistor network. These parts are suitable for applications where dual NPN functionality replaces the original NPN/PNP configuration. MUN5232DW1T1G offers 250mW power dissipation, while SMUN5232DW1T1G provides 187mW. Selection between these onsemi parts depends on power budget requirements.

Selection Criteria Summary

For direct pin-compatible replacement: Use RN4901,LF(CT.

For automotive applications: Use PUMD15,115, PUMD15,135, or PUMH15,115.

For dual NPN functionality: Use MUN5232DW1T1G or SMUN5232DW1T1G.

All recommended substitutes are active products with ROHS3 compliance and MSL 1 rating.

Frequently Asked Questions (FAQ)

Q: Can RN4901,LF(CT be used as a direct replacement for the obsolete RN4901,LF?

A: Yes. RN4901,LF(CT is the direct equivalent with identical electrical specifications, transistor configuration, and package format. The only difference is product status (active versus obsolete) and ROHS3 compliance certification.

Q: What is the difference between PUMD15,115 and PUMD15,135?

A: Both parts are functionally identical with the same electrical ratings, transistor configuration (1 NPN, 1 PNP), and package format. They are interchangeable for design purposes.

Q: Can PUMH15,115 replace the RN4901,LF in all applications?

A: PUMH15,115 is a dual NPN configuration, whereas the RN4901,LF contains 1 NPN and 1 PNP. PUMH15,115 is suitable only for circuits where dual NPN transistors provide the required functionality. Circuit topology must be evaluated to confirm compatibility.

Q: What is the advantage of Nexperia parts (PUMD15, PUMH15) over the Toshiba RN4901,LF(CT?

A: Nexperia parts offer higher power dissipation (300mW versus 200mW) and carry AEC-Q100 automotive qualification. These advantages are relevant for automotive applications or designs requiring higher thermal headroom. For non-automotive applications with standard power requirements, RN4901,LF(CT is the direct equivalent.

Q: Are onsemi MUN5232DW1T1G and SMUN5232DW1T1G interchangeable?

A: Both parts are dual NPN pre-biased transistors with identical electrical ratings and package format. The primary difference is power dissipation: MUN5232DW1T1G provides 250mW, while SMUN5232DW1T1G provides 187mW. Selection depends on circuit power requirements. They are not interchangeable if power dissipation specifications are critical.

Q: Do all substitute parts use the same package footprint?

A: All substitute parts use 6-TSSOP, SC-88, or SOT-363 packages, which share compatible footprints for surface mount PCB assembly. Verify specific package designation in component datasheets to confirm footprint compatibility with existing PCB designs.

Q: What does MSL 1 (Unlimited) mean for moisture sensitivity?

A: MSL 1 indicates the lowest moisture sensitivity level, meaning the component has unlimited shelf life under standard storage conditions without requiring special moisture-control packaging or baking procedures prior to assembly.

Q: Are all recommended substitutes ROHS3 compliant?

A: Yes. All active substitute parts listed (RN4901,LF(CT, PUMD15,115, PUMD15,135, PUMH15,115, MUN5232DW1T1G, SMUN5232DW1T1G) are ROHS3 compliant, meeting regulatory requirements for hazardous substance restrictions.

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