MMQA24VT1 Transient Voltage Suppressor (TVS) Diode - Equivalent & Substitute Parts

Part Overview

The MMQA24VT1 is a unidirectional transient voltage suppressor diode manufactured by onsemi, designed for general-purpose overvoltage protection in surface-mount applications. This component features a 18V reverse standoff voltage with 34.6V maximum clamping voltage and 694mA peak pulse current capability in an SC-74 package. The product is classified as obsolete, necessitating identification of active equivalent alternatives that maintain electrical and mechanical compatibility for ongoing design support and production requirements.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	18V (Max)	V
Voltage - Breakdown (Min)	22.8V	V
Voltage - Clamping (Max) @ Ipp	34.6V	V
Current - Peak Pulse (10/1000µs)	694mA (8/20µs)	mA
Power - Peak Pulse	150W	W
Type	Zener	—
Unidirectional Channels	4	—
Operating Temperature Range	-55°C to 150°C	°C (TJ)
Mounting Type	Surface Mount	—
Package / Case	SC-74, SOT-457	—
RoHS Status	RoHS non-compliant	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the MMQA24VT1 is determined by the following critical electrical and mechanical parameters:

Primary Substitution Criteria:

Unidirectional channel configuration (4 channels required)
Voltage - Reverse Standoff: 18V nominal operation
Voltage - Clamping (Max) @ Ipp: 34.6V maximum threshold
Current - Peak Pulse capability: 694mA minimum
Power - Peak Pulse dissipation: 150W minimum
Surface-mount package compatibility (SC-74 / SOT-457)
Operating temperature range: -55°C to 150°C minimum

The substitute parts identified from the provided list are grouped into two distinct voltage classes based on their reverse standoff and clamping voltage specifications:

Group 1 - BZA420A Series (20V Standoff, 28V Clamp): BZA420A,115 | BZA420A,125 | BZA420A,165 These parts operate at a higher voltage class (20V standoff vs. 18V) with lower clamping voltage (28V vs. 34.6V), suitable for applications requiring reduced overvoltage margin.

Group 2 - BZA456A Series (5.6V Standoff, 8V Clamp): BZA456A,115 | BZA456A,125 | BZA456A,135 | BZA456A,165 These parts operate at a significantly lower voltage class (5.6V standoff vs. 18V) with proportionally lower clamping voltage (8V vs. 34.6V), applicable only to low-voltage protection circuits.

Parameter Comparison

Parameter	MMQA24VT1	BZA420A,115	BZA420A,125	BZA420A,135	BZA420A,165	BZA456A,115	BZA456A,125	BZA456A,135	BZA456A,165
Manufacturer	onsemi	Nexperia USA Inc.	Nexperia USA Inc.	Nexperia USA Inc.	Nexperia USA Inc.	Nexperia USA Inc.	Nexperia USA Inc.	Nexperia USA Inc.	Nexperia USA Inc.
Product Status	Obsolete	Active	Active	Active	Active	Active	Active	Active	Active
Type	Zener	Zener	Zener	Zener	Zener	Zener	Zener	Zener	Zener
Unidirectional Channels	4	4	4	4	4	4	4	4	4
Voltage - Reverse Standoff (Typ)	18V	20V	20V	20V	20V	5.6V	5.6V	5.6V	5.6V
Voltage - Clamping (Max) @ Ipp	34.6V	28V	28V	28V	28V	8V	8V	8V	8V
Current - Peak Pulse (10/1000µs)	694mA (8/20µs)	—	—	—	—	3A (8/20µs)	3A (8/20µs)	3A (8/20µs)	3A (8/20µs)
Power - Peak Pulse	150W	19.6W	19.6W	19.6W	19.6W	24W	24W	24W	24W
Operating Temperature Range	-55°C to 150°C	-65°C to 150°C	-65°C to 150°C	-65°C to 150°C	-65°C to 150°C	-65°C to 150°C	-65°C to 150°C	-65°C to 150°C	-65°C to 150°C
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Package / Case	SC-74, SOT-457	SC-74, SOT-457	SC-74, SOT-457	SC-74, SOT-457	SC-74, SOT-457	SC-74, SOT-457	SC-74, SOT-457	SC-74, SOT-457	SC-74, SOT-457
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Qualification	—	AEC-Q100	AEC-Q100	AEC-Q100	AEC-Q100	AEC-Q100	AEC-Q100	AEC-Q100	AEC-Q100
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

For Direct Voltage-Class Substitution (18V Protection Level): The BZA420A series (BZA420A,115 | BZA420A,125 | BZA420A,165) represents the closest electrical equivalent to the MMQA24VT1 within the provided substitute list. These parts maintain the same 4-channel unidirectional configuration, surface-mount SC-74 package, and operating temperature range. All BZA420A variants are active products with AEC-Q100 automotive qualification and ROHS3 compliance, addressing the obsolescence of the original onsemi component.

The BZA420A series operates at 20V reverse standoff with 28V maximum clamping voltage, representing a 2V increase in standoff voltage and 6.6V reduction in clamping voltage compared to the MMQA24VT1. This voltage shift requires circuit-level evaluation to confirm compatibility with the protected signal path.

For Low-Voltage Protection Applications (5.6V Protection Level): The BZA456A series (BZA456A,115 | BZA456A,125 | BZA456A,135 | BZA456A,165) is applicable only to circuits requiring protection at significantly lower voltage thresholds. These parts feature 5.6V reverse standoff with 8V maximum clamping voltage and deliver 3A peak pulse current with 24W peak power dissipation. Selection within this series is determined by packaging tape reel specifications (,115 | ,125 | ,135 | ,165 designations).

Compliance Considerations: All identified substitute parts are ROHS3 compliant and carry AEC-Q100 automotive qualification, providing regulatory and quality assurance advantages over the obsolete MMQA24VT1. Inventory availability ranges from 731 to 15,300 units across the substitute options, supporting production continuity.

Frequently Asked Questions (FAQ)

Q: Can BZA420A series parts directly replace MMQA24VT1 in existing designs? A: BZA420A parts share identical package geometry (SC-74, SOT-457), channel configuration (4 unidirectional), and operating temperature range (-65°C to 150°C). However, the voltage specifications differ: BZA420A operates at 20V standoff with 28V clamping versus MMQA24VT1's 18V standoff with 34.6V clamping. Circuit validation is required to confirm the 2V standoff increase and 6.6V clamping reduction are acceptable for the protected application.

Q: What is the difference between BZA420A,115 | BZA420A,125 | BZA420A,165 variants? A: These designations represent different tape and reel packaging specifications for the same electrical component. The core electrical parameters (20V standoff, 28V clamping, 4 channels) are identical across all variants. Selection depends on procurement and assembly equipment compatibility with the specified packaging format.

Q: Are BZA456A parts suitable as MMQA24VT1 replacements? A: BZA456A parts are not suitable for direct replacement in circuits designed for 18V protection. These components operate at 5.6V reverse standoff with 8V clamping voltage, appropriate only for low-voltage signal protection applications. Use BZA456A only if circuit requirements specifically call for 5.6V protection thresholds.

Q: What compliance advantages do substitute parts offer? A: All identified substitute parts (BZA420A and BZA456A series) are ROHS3 compliant and AEC-Q100 qualified, compared to the MMQA24VT1's RoHS non-compliant status. This provides regulatory alignment with current environmental standards and automotive quality requirements.

Q: How do peak pulse current ratings compare? A: MMQA24VT1 specifies 694mA peak pulse current (8/20µs). BZA420A series does not provide peak pulse current specification in the available data. BZA456A series delivers 3A (8/20µs), which exceeds the original component's capability but applies only to the lower 5.6V voltage class.

Q: What inventory considerations apply to substitute selection? A: BZA420A,115 offers 12,150 units in stock, BZA420A,125 provides 6,964 units, and BZA420A,165 has 1,138 units available. BZA456A variants range from 797 to 15,300 units. Selection should account for production volume requirements and supply continuity.

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