SF18-TP Equivalent & Substitute Parts

Part Overview

The SF18-TP is a general-purpose rectifier diode rated for 600 V DC reverse voltage and 1 A average rectified current in a through-hole DO-41 package. Manufactured by Micro Commercial Co, this component is classified as obsolete. Identifying equivalent and substitute parts is necessary to maintain design continuity and ensure component availability for new production runs, repairs, and legacy system support.

Key Parameters

Parameter	Value
Voltage - DC Reverse (Vr) (Max)	600 V
Current - Average Rectified (Io)	1 A
Voltage - Forward (Vf) (Max) @ If	1.7 V @ 1 A
Speed	Fast Recovery ≤ 500ns, > 200mA (Io)
Reverse Recovery Time (trr)	35 ns
Current - Reverse Leakage @ Vr	5 µA @ 600 V
Mounting Type	Through Hole
Package / Case	DO-204AL, DO-41, Axial
Operating Temperature - Junction	-55°C ~ 125°C
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitute parts for the SF18-TP are selected based on electrical and mechanical compatibility within the following criteria:

Electrical Parameters (Must Match or Exceed):

Voltage - DC Reverse (Vr) (Max): 600 V minimum
Current - Average Rectified (Io): 1 A minimum
Speed Classification: Fast Recovery ≤ 500ns, > 200mA (Io)
Reverse Recovery Time (trr): Must support fast recovery operation
Current - Reverse Leakage @ Vr: 5 µA @ 600 V maximum

Mechanical Parameters (Must Match):

Mounting Type: Through Hole
Package / Case: DO-204AL, DO-41, or Axial equivalent
Supplier Device Package: DO-41 or DO-204AL (DO-41)

Compliance Parameters:

RoHS Status: ROHS3 Compliant
Moisture Sensitivity Level (MSL): 1 (Unlimited)

Substitute parts are grouped into direct equivalents (same manufacturer, active product status) and similar alternatives (different manufacturers, enhanced specifications or certifications).

Parameter Comparison

Part Number	Manufacturer	Product Status	Vr (Max)	Io	Vf (Max) @ If	trr (ns)	Ir @ Vr	Package	Temp Range
SF18-TP	Micro Commercial Co	Obsolete	600 V	1 A	1.7 V @ 1 A	35	5 µA @ 600 V	DO-41	-55°C ~ 125°C
SF18G-TP	Micro Commercial Co	Active	600 V	1 A	1.3 V @ 1 A	35	5 µA @ 600 V	DO-41	-55°C ~ 150°C
1N4937E-E3/53	Vishay General Semiconductor - Diodes Division	Active	600 V	1 A	1.2 V @ 1 A	200	5 µA @ 600 V	DO-204AL (DO-41)	-55°C ~ 125°C
UF1JHR1G	Taiwan Semiconductor Corporation	Active	600 V	1 A	1.7 V @ 1 A	75	5 µA @ 600 V	DO-204AL (DO-41)	-55°C ~ 150°C
UF4005	Fairchild Semiconductor	Active	600 V	1 A	1.7 V @ 1 A	75	5 µA @ 600 V	DO-41	-50°C ~ 175°C
UF4005 B0G	Taiwan Semiconductor Corporation	Active	600 V	1 A	1.7 V @ 1 A	75	5 µA @ 600 V	DO-204AL (DO-41)	-55°C ~ 150°C

Engineering Selection Recommendations

Direct Equivalent (Recommended Primary Substitute):

SF18G-TP is the recommended primary substitute. Manufactured by the same supplier (Micro Commercial Co), this part maintains design continuity and carries active product status. The SF18G-TP offers improved forward voltage characteristics (1.3 V vs. 1.7 V @ 1 A) and an extended operating temperature range (-55°C ~ 150°C vs. -55°C ~ 125°C). Both parts share identical reverse voltage, current rating, reverse recovery time, and reverse leakage specifications. Packaging is identical (DO-41). RoHS3 compliance and MSL 1 rating are maintained.

Alternative Substitutes (Active Status, Enhanced Specifications):

1N4937E-E3/53 (Vishay) provides the lowest forward voltage (1.2 V @ 1 A) among all candidates, supporting applications requiring minimal power dissipation. This part is ROHS3 compliant and REACH unaffected. The reverse recovery time is extended to 200 ns, which may affect switching performance in high-frequency applications compared to the SF18-TP baseline of 35 ns.

UF1JHR1G (Taiwan Semiconductor Corporation) is qualified to AEC-Q101 automotive standards and carries extended operating temperature range (-55°C ~ 150°C). This part is suitable for automotive and industrial applications requiring formal qualification documentation. Reverse recovery time is 75 ns.

UF4005 (Fairchild Semiconductor) and UF4005 B0G (Taiwan Semiconductor Corporation) are widely available alternatives with extended upper operating temperature limits (175°C for Fairchild variant). Both maintain 600 V / 1 A ratings and fast recovery characteristics. UF4005 B0G includes REACH compliance documentation.

Product Status Consideration:

The SF18-TP is classified as obsolete. All recommended substitutes carry active product status, ensuring long-term availability and continued manufacturing support.

Frequently Asked Questions (FAQ)

Q: Can SF18G-TP be used as a direct replacement for SF18-TP?

A: Yes. SF18G-TP is a direct equivalent manufactured by the same supplier. Both parts share identical electrical ratings (600 V, 1 A, 35 ns reverse recovery time) and package configuration (DO-41). SF18G-TP offers improved forward voltage performance and extended temperature range. No circuit modifications are required.

Q: What is the difference between DO-41 and DO-204AL packaging?

A: DO-41 and DO-204AL are equivalent package designations for the same through-hole axial diode form factor. Both refer to a cylindrical component with axial leads. Parts specified as DO-204AL (DO-41) or DO-41 are mechanically and electrically interchangeable in PCB applications.

Q: Why does 1N4937E-E3/53 have a longer reverse recovery time (200 ns) than SF18-TP (35 ns)?

A: Reverse recovery time varies by semiconductor design and manufacturing process. The 1N4937E-E3/53 exhibits slower recovery characteristics, which may introduce additional switching losses in high-frequency rectification circuits. For applications sensitive to reverse recovery time, SF18G-TP or UF4005 variants are preferred.

Q: Is UF1JHR1G suitable for automotive applications?

A: Yes. UF1JHR1G carries AEC-Q101 automotive qualification and is designated as automotive grade. This part is appropriate for automotive and industrial applications requiring formal qualification documentation and extended temperature operation (-55°C ~ 150°C).

Q: What is the significance of forward voltage differences among substitutes?

A: Forward voltage (Vf) directly affects power dissipation in rectification circuits. Lower Vf values reduce heat generation. SF18G-TP (1.3 V) and 1N4937E-E3/53 (1.2 V) dissipate less power than SF18-TP (1.7 V). For thermal-sensitive applications, lower Vf alternatives reduce cooling requirements.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All substitute parts listed carry RoHS3 compliance certification. SF18G-TP, 1N4937E-E3/53, UF1JHR1G, UF4005, and UF4005 B0G are all ROHS3 compliant, meeting environmental and regulatory requirements for lead-free manufacturing.

Q: Can UF4005 operate at higher temperatures than SF18-TP?

A: Yes. UF4005 (Fairchild variant) supports operating temperatures up to 175°C, compared to SF18-TP at 125°C. This extended range is beneficial for high-temperature environments. However, most alternative substitutes (SF18G-TP, UF1JHR1G, UF4005 B0G) operate to 150°C, which covers most industrial applications.

Q: What is the inventory status of substitute parts?

A: All substitute parts are listed as in-stock with new original inventory: SF18G-TP (862 pcs), 1N4937E-E3/53 (1056 pcs), UF1JHR1G (952 pcs), UF4005 (1780 pcs), and UF4005 B0G (1119 pcs). Availability is confirmed at the time of this reference.

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