FN4L4M-T1B-A Equivalent & Substitute Parts

Part Overview

The FN4L4M-T1B-A is a pre-biased NPN bipolar transistor manufactured by Renesas Electronics Corporation, rated for 50 V collector-emitter breakdown voltage and 100 mA maximum collector current. This device integrates internal base and emitter-base resistors (22 kOhms each) for simplified circuit design in switching and amplification applications.

The FN4L4M-T1B-A is classified as obsolete. Substitute parts are necessary to maintain design continuity and ensure long-term component availability for production and field service applications. Available alternatives include active pre-biased PNP transistors with equivalent electrical ratings and compatible package configurations.

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)	22	kOhms
Resistor - Emitter Base (R2)	22	kOhms
DC Current Gain (hFE) Min @ Ic, Vce	85 @ 5mA, 5V
Vce Saturation (Max) @ Ib, Ic	200mV @ 250µA, 5mA
Current - Collector Cutoff (Max)	100	nA
Power - Max	200	mW
Moisture Sensitivity Level (MSL)	1 (Unlimited)
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitute parts for the FN4L4M-T1B-A are selected based on the following electrical and mechanical criteria:

Critical Matching Parameters:

Maximum collector current: 100 mA
Collector-emitter breakdown voltage: 50 V
Maximum power dissipation: 200 mW or greater
Pre-biased configuration with integrated base resistors
Moisture sensitivity level: 1 (Unlimited)

Polarity Consideration: The FN4L4M-T1B-A is an NPN pre-biased transistor. All identified substitute parts are PNP pre-biased transistors. PNP devices operate with reversed polarity and require circuit redesign for direct substitution. However, they satisfy the electrical performance envelope and are listed as functional equivalents in the provided substitute list.

Internal Resistor Values: Substitute parts feature 47 kOhms base and emitter-base resistors, compared to 22 kOhms in the original part. This difference affects bias current and switching characteristics but remains within acceptable design margins for general-purpose switching applications.

Active Product Status: All substitute parts listed are active products with current manufacturing support, ensuring long-term availability and supply chain continuity.

Parameter Comparison

Parameter	FN4L4M-T1B-A	DTA144ECA-TP	DTA144ECAT116	MMUN2113LT1G	MMUN2113LT3G	MUN2113T1G	PDTA144ET,215	PDTA144ET,235	SMMUN2113LT1G
Transistor Type	NPN	PNP	PNP	PNP	PNP	PNP	PNP	PNP	PNP
Ic (Max) [mA]	100	100	100	100	100	100	100	100	100
Vce Breakdown (Max) [V]	50	50	50	50	50	50	50	50	50
R1 Base [kOhms]	22	47	47	47	47	47	47	47	47
R2 Emitter-Base [kOhms]	22	47	47	47	47	47	47	47	47
hFE (Min) @ Ic, Vce	85 @ 5mA, 5V	68 @ 5mA, 5V	68 @ 5mA, 5V	80 @ 5mA, 10V	80 @ 5mA, 10V	80 @ 5mA, 10V	80 @ 5mA, 5V	80 @ 5mA, 5V	80 @ 5mA, 10V
Vce Sat (Max) @ Ib, Ic	200mV @ 250µA, 5mA	300mV @ 500µA, 10mA	300mV @ 500µA, 10mA	250mV @ 300µA, 10mA	250mV @ 300µA, 10mA	250mV @ 300µA, 10mA	150mV @ 500µA, 10mA	150mV @ 500µA, 10mA	250mV @ 300µA, 10mA
Icbo (Max) [nA]	100	500	500	500	500	500	1000	1000	500
Power (Max) [mW]	200	200	200	246	246	230	250	250	246
Mounting Type	Through-Hole	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Package	Not Specified	SOT-23	SST3	SOT-23-3	SOT-23-3	SC-59	TO-236AB	TO-236AB	SOT-23-3
Product Status	Obsolete	Active	Active	Active	Active	Active	Active	Active	Active
RoHS Status	Not Specified	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
MSL	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

For Active Production Designs:

All substitute parts listed are active products with current manufacturing support. Selection among substitutes depends on packaging requirements and supply availability:

MMUN2113LT1G and SMMUN2113LT1G: Highest inventory availability (32,100 and 23,100 units respectively). SMMUN2113LT1G includes AEC-Q101 automotive qualification for applications requiring automotive-grade components.
PDTA144ET,235: Largest inventory among Nexperia devices (10,741 units). Offers lowest saturation voltage (150 mV) among all substitutes, beneficial for low-voltage switching applications.
MUN2113T1G: Moderate inventory (2,783 units). SC-59 package option for space-constrained designs.

For Legacy Design Maintenance:

When retrofitting obsolete FN4L4M-T1B-A designs, circuit polarity must be reversed to accommodate PNP substitutes. Base and emitter-base resistor values differ (47 kOhms vs. 22 kOhms), requiring bias network recalculation.

Compliance Considerations:

All substitute parts are ROHS3 compliant and REACH unaffected, meeting current environmental and regulatory requirements. MSL rating of 1 (Unlimited) matches the original part specification.

Frequently Asked Questions (FAQ)

Q: Can the FN4L4M-T1B-A be directly replaced with a PNP substitute without circuit modification?

A: No. The FN4L4M-T1B-A is NPN; all substitutes are PNP. PNP transistors require reversed polarity in the circuit. Direct pin-for-pin substitution will not function. Circuit redesign is necessary.

Q: What is the impact of different internal resistor values (22 kOhms vs. 47 kOhms)?

A: The higher resistor values in substitute parts reduce base bias current. This affects switching speed and saturation characteristics. Designs must be re-evaluated for bias point stability and switching performance. Substitutes remain functional for general-purpose switching but may require bias network adjustment.

Q: Which substitute offers the best availability?

A: MMUN2113LT1G has the highest inventory (32,100 units). SMMUN2113LT1G (23,100 units) is the second choice and includes automotive qualification.

Q: Are all substitutes surface-mount devices?

A: Yes. All listed substitutes are surface-mount components in SOT-23, SST3, SC-59, or TO-236AB packages. The original FN4L4M-T1B-A package type is not specified in the provided data. Through-hole alternatives are not available in the substitute list.

Q: What is the difference between MMUN2113LT1G and MMUN2113LT3G?

A: Both devices are electrically identical. The difference is packaging: MMUN2113LT1G is supplied in Tape & Reel (TR), while MMUN2113LT3G is supplied in Cut Tape (CT) & Digi-Reel®. Selection depends on assembly process requirements.

Q: Is SMMUN2113LT1G suitable for automotive applications?

A: Yes. SMMUN2113LT1G carries AEC-Q101 automotive qualification, making it appropriate for automotive-grade designs. Other substitutes are not specified with automotive qualification.

Q: How do saturation voltage differences affect circuit design?

A: PDTA144ET,215 and PDTA144ET,235 offer the lowest saturation voltage (150 mV), compared to 200-300 mV in other substitutes. Lower saturation voltage reduces power dissipation in saturated switching applications and improves noise margins in logic circuits.

Q: Can substitutes be used interchangeably in the same design?

A: Substitutes with identical electrical parameters (hFE, Vce Sat, Icbo) can be used interchangeably if package compatibility is confirmed. However, internal resistor value differences (47 kOhms) require bias network verification across all substitutes.

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