RSFALH Equivalent & Substitute Parts

Part Overview

The RSFALH is a fast recovery rectifier diode manufactured by Taiwan Semiconductor Corporation, rated for 50V DC reverse voltage and 500mA average rectified current. This component features a 150ns reverse recovery time and is housed in a SOD-123 surface mount package. The RSFALH carries an automotive grade qualification (AEC-Q101) and is RoHS3 compliant.

The RSFALH is designated as "Not For New Designs," indicating it has reached end-of-life status. Identification of equivalent and substitute parts is necessary for ongoing maintenance, repair, and legacy system support where this component remains in active use.

Key Parameters

Parameter	Value	Unit
Voltage - DC Reverse (Vr) (Max)	50	V
Current - Average Rectified (Io)	500	mA
Voltage - Forward (Vf) (Max) @ If	1.3 @ 500 mA	V
Reverse Recovery Time (trr)	150	ns
Current - Reverse Leakage @ Vr	5 @ 50 V	µA
Speed Classification	Fast Recovery ≤ 500ns, > 200mA	-
Package / Case	SOD-123	-
Mounting Type	Surface Mount	-
Operating Temperature - Junction	-55 to 150	°C
Grade	Automotive	-
Qualification	AEC-Q101	-

Substitute Part Grouping Explanation

Substitution of the RSFALH is determined by the following critical electrical and mechanical parameters:

Electrical Compatibility Requirements:

Reverse voltage rating must equal or exceed the application requirement (50V minimum)
Average rectified current capacity must equal or exceed the application requirement (500mA minimum)
Reverse recovery time must remain within fast recovery classification (≤ 500ns, > 200mA)
Forward voltage drop must be compatible with circuit design specifications
Reverse leakage current must not exceed acceptable limits for the application

Mechanical Compatibility Requirements:

Surface mount package type must be compatible with PCB layout and assembly equipment
Operating temperature range must encompass the application environment
Automotive grade qualification (AEC-Q101) must be maintained for automotive applications

Compliance Requirements:

RoHS3 compliance status must be maintained
REACH compliance status must be maintained

The RS1DLWH qualifies as a substitute part because it meets or exceeds all critical electrical parameters while maintaining automotive qualification and compliance certifications.

Parameter Comparison

Parameter	RSFALH	RS1DLWH	Notes
Manufacturer	Taiwan Semiconductor Corporation	Taiwan Semiconductor Corporation	Same manufacturer
Category	Diodes, Rectifiers	Diodes, Rectifiers	Same component category
Voltage - DC Reverse (Vr) (Max)	50 V	200 V	RS1DLWH rated higher
Current - Average Rectified (Io)	500 mA	1 A	RS1DLWH rated higher
Voltage - Forward (Vf) (Max) @ If	1.3 V @ 500 mA	1.3 V @ 1 A	Equivalent forward voltage
Reverse Recovery Time (trr)	150 ns	150 ns	Identical
Current - Reverse Leakage @ Vr	5 µA @ 50 V	5 µA @ 200 V	Equivalent leakage characteristic
Speed Classification	Fast Recovery ≤ 500ns, > 200mA	Fast Recovery ≤ 500ns, > 200mA	Identical classification
Mounting Type	Surface Mount	Surface Mount	Same mounting technology
Operating Temperature - Junction	-55 to 150 °C	-55 to 175 °C	RS1DLWH has extended upper range
Grade	Automotive	Automotive	Same grade
Qualification	AEC-Q101	AEC-Q101	Same qualification
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	Same compliance
REACH Status	REACH Unaffected	REACH Unaffected	Same compliance
Product Status	Not For New Designs	Active	RS1DLWH is actively supported
Package / Case	SOD-123	SOD-123W	Different package variants

Engineering Selection Recommendations

RS1DLWH as Primary Substitute:

The RS1DLWH is the manufacturer-recommended substitute for the RSFALH. This substitution is valid based on the following engineering criteria:

Electrical Superiority: The RS1DLWH exceeds the RSFALH in both reverse voltage rating (200V vs. 50V) and current capacity (1A vs. 500mA), ensuring compatibility with applications designed for the RSFALH while providing additional design margin.
Identical Speed Characteristics: Both devices maintain identical 150ns reverse recovery time and fast recovery classification, ensuring equivalent switching performance in rectification circuits.
Equivalent Forward Voltage: Forward voltage drop remains at 1.3V across the rated current range, maintaining circuit performance and power dissipation characteristics.
Automotive Qualification Maintained: Both devices carry AEC-Q101 automotive qualification, preserving suitability for automotive applications.
Compliance Continuity: RoHS3 and REACH compliance status is maintained, ensuring regulatory alignment.
Active Product Status: The RS1DLWH is designated as "Active," providing ongoing manufacturer support, availability, and supply chain continuity compared to the end-of-life RSFALH.
Package Consideration: The RS1DLWH uses SOD-123W packaging, a variant of the SOD-123 family. PCB layout verification is required to confirm physical compatibility with existing RSFALH footprints, as package dimensions may differ.

Frequently Asked Questions (FAQ)

Q: Can the RS1DLWH directly replace the RSFALH without circuit modification?

A: The RS1DLWH is electrically compatible with applications designed for the RSFALH. The higher voltage and current ratings of the RS1DLWH provide backward compatibility. However, PCB footprint verification is required due to the SOD-123W package variant. Consult PCB layout documentation and package datasheets to confirm physical compatibility.

Q: What is the significance of the higher voltage rating on the RS1DLWH?

A: The RS1DLWH is rated for 200V reverse voltage compared to the RSFALH's 50V rating. This higher rating provides additional design margin and allows the RS1DLWH to function in applications with higher voltage requirements. In applications designed for 50V operation, the RS1DLWH operates within its safe operating area with increased voltage headroom.

Q: Are the reverse recovery times identical between these devices?

A: Yes. Both the RSFALH and RS1DLWH have a reverse recovery time of 150ns and are classified as fast recovery diodes. This ensures equivalent switching performance in rectification and freewheeling applications.

Q: What is the difference between SOD-123 and SOD-123W packages?

A: SOD-123 and SOD-123W are both surface mount packages in the SOD family but have different physical dimensions. The SOD-123W is a wider variant. PCB footprint compatibility must be verified before substitution. Consult the respective package datasheets for dimensional specifications.

Q: Is the RS1DLWH suitable for automotive applications?

A: Yes. The RS1DLWH carries automotive grade qualification (AEC-Q101), identical to the RSFALH. It is suitable for automotive applications requiring fast recovery rectifier diodes.

Q: Why is the RSFALH marked as "Not For New Designs"?

A: The "Not For New Designs" designation indicates the RSFALH has reached end-of-life status. New designs should utilize the RS1DLWH or other active alternatives. Existing systems using the RSFALH can continue to source the RS1DLWH as a substitute for maintenance and repair.

Q: Are there any compliance differences between the RSFALH and RS1DLWH?

A: No. Both devices are RoHS3 compliant and REACH unaffected. Compliance status is maintained across the substitution.

Q: What inventory status should be considered for component selection?

A: The RS1DLWH has significantly higher inventory availability (20,765 pcs) compared to the RSFALH (1,095 pcs). This availability advantage supports long-term supply chain reliability for ongoing production and maintenance requirements.

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