KMB125S Equivalent & Substitute Parts

Part Overview

The KMB125S is a single-phase Schottky bridge rectifier diode manufactured by SMC Diode Solutions, rated for 1 A average rectified current at 250 V peak reverse voltage. The device is packaged in a 4-SMD Gull Wing surface mount configuration with an MBS supplier package designation. The KMB125S is classified as obsolete, necessitating identification of active equivalent components for new designs and ongoing production requirements. Substitute parts must maintain functional compatibility across rectification performance, thermal operating range, and mounting characteristics.

Key Parameters

Parameter	Value
Diode Type	Single Phase
Technology	Schottky
Current - Average Rectified (Io)	1 A
Voltage - Peak Reverse (Max)	250 V
Voltage - Forward (Vf) (Max) @ If	920 mV @ 1 A
Current - Reverse Leakage @ Vr	50 µA @ 250 V
Operating Temperature Range	-55°C ~ 150°C (TJ)
Mounting Type	Surface Mount
Package / Case	4-SMD, Gull Wing
Supplier Device Package	MBS
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the KMB125S is determined by the following critical parameters:

Mandatory Compatibility Criteria:

Diode Type: Single Phase
Technology: Schottky
Current - Average Rectified (Io): 1 A
Mounting Type: Surface Mount
Package / Case: 4-SMD, Gull Wing
Supplier Device Package: MBS
Operating Temperature Range: -55°C ~ 150°C (TJ)

Voltage Rating Consideration: The KMB125S operates at 250 V peak reverse voltage. Substitute parts with equal or higher voltage ratings maintain full functional compatibility. Parts with lower voltage ratings do not qualify as direct substitutes due to reduced voltage headroom in rectification circuits.

The KMB120S is identified as a manufacturer-recommended substitute despite operating at 200 V peak reverse voltage. This substitution is valid only in applications where the circuit design operates below 200 V, as the lower voltage rating represents a functional constraint rather than an enhancement.

Parameter Comparison

Parameter	KMB125S (Main Part)	KMB120S (Substitute)
Manufacturer	SMC Diode Solutions	SMC Diode Solutions
Diode Type	Single Phase	Single Phase
Technology	Schottky	Schottky
Current - Average Rectified (Io)	1 A	1 A
Voltage - Peak Reverse (Max)	250 V	200 V
Voltage - Forward (Vf) (Max) @ If	920 mV @ 1 A	900 mV @ 1 A
Current - Reverse Leakage @ Vr	50 µA @ 250 V	50 µA @ 200 V
Operating Temperature Range	-55°C ~ 150°C (TJ)	-55°C ~ 150°C (TJ)
Mounting Type	Surface Mount	Surface Mount
Package / Case	4-SMD, Gull Wing	4-SMD, Gull Wing
Supplier Device Package	MBS	MBS
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)
Product Status	Obsolete	Active
RoHS Status	Not specified	ROHS3 Compliant

Engineering Selection Recommendations

KMB120S Selection Criteria:

The KMB120S is the manufacturer-recommended substitute for the obsolete KMB125S. Selection of the KMB120S is appropriate when the following conditions are met:

Voltage Rating Compatibility: The application circuit operates at or below 200 V peak reverse voltage. The KMB120S provides equivalent rectification performance within this voltage envelope.
Product Status: The KMB120S maintains active product status with 653 units in current inventory, ensuring supply chain continuity and long-term availability compared to the obsolete KMB125S.
Compliance Requirements: The KMB120S is ROHS3 compliant, meeting modern regulatory requirements for new product designs and manufacturing operations.
Electrical Performance: Forward voltage drop is reduced to 900 mV at 1 A compared to 920 mV for the KMB125S, resulting in marginally improved efficiency characteristics.
Thermal and Mechanical Compatibility: Operating temperature range, mounting type, package configuration, and moisture sensitivity level are identical to the KMB125S, enabling direct PCB layout compatibility.

Application Limitation:

The KMB120S is not suitable for circuits requiring 250 V peak reverse voltage operation. In such applications, alternative Schottky bridge rectifiers with 250 V or higher ratings must be evaluated.

Frequently Asked Questions (FAQ)

Q: Can the KMB120S directly replace the KMB125S in all applications?

A: The KMB120S is a direct substitute only in applications where the circuit operates at 200 V peak reverse voltage or below. If the circuit design requires 250 V operation, the KMB120S does not provide adequate voltage headroom and cannot be used as a substitute.

Q: What is the primary reason for substituting the KMB125S?

A: The KMB125S is classified as obsolete. The KMB120S is the manufacturer-recommended active alternative, ensuring continued supply availability and compliance with current regulatory standards.

Q: Are the physical packages identical between KMB125S and KMB120S?

A: Yes. Both devices use 4-SMD Gull Wing surface mount packaging with MBS supplier device package designation. PCB footprints and reflow soldering profiles are identical.

Q: What is the difference in forward voltage drop between these parts?

A: The KMB125S exhibits 920 mV forward voltage drop at 1 A, while the KMB120S exhibits 900 mV at 1 A. This 20 mV difference results in marginally lower power dissipation with the KMB120S.

Q: Does the KMB120S meet RoHS compliance requirements?

A: Yes. The KMB120S is ROHS3 compliant. The KMB125S compliance status is not specified in available documentation.

Q: Are the operating temperature ranges the same?

A: Yes. Both the KMB125S and KMB120S operate across -55°C to 150°C junction temperature range, providing identical thermal performance characteristics.

Q: What is the moisture sensitivity level for both parts?

A: Both devices are rated MSL 1 (Unlimited), indicating no moisture sensitivity restrictions for storage, handling, or reflow processing.

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