MMSZ5250B Zener Diode Equivalent & Substitute Parts

Part Overview

The MMSZ5250B is a 20 V, 500 mW Zener diode manufactured by onsemi in SOD-123 surface mount packaging. This component is classified as obsolete, though 305,300 pieces remain in stock as new original inventory. The part operates across a temperature range of -55°C to 150°C with ±5% voltage tolerance and is suitable for voltage regulation and protection applications in electronic circuits.

Due to its obsolete status, identifying equivalent and substitute parts is necessary for design continuity, long-term supply chain planning, and new product development. Active alternatives with identical or superior electrical characteristics are available from onsemi and other manufacturers.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	20	V
Tolerance	±5%	-
Power - Max	500	mW
Impedance (Max)	25	Ohms
Current - Reverse Leakage @ Vr	100 nA @ 15 V	-
Voltage - Forward (Vf) (Max) @ If	900 mV @ 10 mA	-
Operating Temperature	-55°C ~ 150°C	-
Mounting Type	Surface Mount	-
Package / Case	SOD-123	-

Substitute Part Grouping Explanation

Substitution of the MMSZ5250B is determined by the following critical parameters: nominal Zener voltage (20 V), maximum power dissipation (500 mW), voltage tolerance (±5%), impedance (25 Ohms maximum), reverse leakage current (100 nA @ 15 V), forward voltage drop (900 mV @ 10 mA), operating temperature range (-55°C to 150°C), and package type (SOD-123 surface mount).

Substitute parts are grouped into the following categories:

Direct Equivalents (Active Status): Parts with identical electrical specifications and active product status, available in alternative packaging formats (Tape & Reel or Cut Tape & Digi-Reel).

Parametric Equivalents: Parts with tighter voltage tolerance (±2%) or automotive-grade qualification (AEC-Q101) that meet or exceed the original specifications.

Similar Parts (Automotive Grade): Automotive-qualified alternatives with AEC-Q101 certification suitable for applications requiring enhanced reliability.

Cross-Manufacturer Alternatives: Equivalent parts from manufacturers other than onsemi that maintain identical electrical and mechanical specifications.

Upgrade Options: Parts with modified power ratings or temperature ranges that provide enhanced performance characteristics.

Parameter Comparison

Part Number	Manufacturer	Product Status	Vz (V)	Tolerance	Power (mW)	Zzt (Ohms)	Reverse Leakage	Vf (mV)	Temp Range (°C)	Packaging	RoHS
MMSZ5250B	onsemi	Obsolete	20	±5%	500	25	100 nA @ 15 V	900 @ 10 mA	-55 ~ 150	SOD-123	-
MMSZ20T1G	onsemi	Active	20	±5%	500	55	50 nA @ 14 V	900 @ 10 mA	-55 ~ 150	Tape & Reel	ROHS3
MMSZ4707T1G	onsemi	Active	20	±5%	500	-	10 nA @ 15.2 V	900 @ 10 mA	-55 ~ 150	Tape & Reel	ROHS3
MMSZ5250BT1G	onsemi	Active	20	±5%	500	25	100 nA @ 15 V	900 @ 10 mA	-55 ~ 150	Cut Tape & Digi-Reel	ROHS3
SZMMSZ20T1G	onsemi	Active	20	±5%	500	55	50 nA @ 14 V	900 @ 10 mA	-55 ~ 150	Tape & Reel	ROHS3
SZMMSZ4707T1G	onsemi	Active	20	-	500	-	10 µA @ 15.2 V	900 @ 10 mA	-55 ~ 150	Tape & Reel	ROHS3
MMSZ5250CT1G	onsemi	Active	20	±2%	500	25	100 nA @ 15 V	900 @ 10 mA	-55 ~ 150	Tape & Reel	ROHS3
SZMMSZ5250BT1G	onsemi	Active	20	±5%	500	25	100 nA @ 15 V	900 @ 10 mA	-55 ~ 150	Tape & Reel	ROHS3
SZMMSZ5250ET1G	onsemi	Active	20	±5%	500	25	100 nA @ 15 V	900 @ 10 mA	-55 ~ 150	Tape & Reel	ROHS3
MMSZ5250B-TP	Micro Commercial Co	Active	20	±5%	500	25	100 nA @ 15 V	900 @ 10 mA	-55 ~ 150	Tape & Reel	ROHS3
MMSZ5250B-13-F	Diodes Incorporated	Active	20	±5%	370	25	100 nA @ 15 V	900 @ 10 mA	-65 ~ 150	Tape & Reel	ROHS3

Engineering Selection Recommendations

For Direct Replacement (Identical Specifications):

MMSZ5250BT1G (onsemi) is the primary direct replacement. This part maintains all electrical parameters of the original MMSZ5250B, including 25 Ohms maximum impedance and 100 nA reverse leakage current at 15 V. The part is active with ROHS3 compliance and available in Cut Tape & Digi-Reel packaging with 149,300 pieces in stock.

MMSZ5250B-TP (Micro Commercial Co) provides an alternative direct equivalent from a different manufacturer. Electrical specifications are identical to the original part, with active product status and ROHS3 compliance. Packaging is Tape & Reel format with 30,905 pieces available.

For Automotive Applications:

SZMMSZ5250BT1G and SZMMSZ5250ET1G (onsemi) are automotive-grade alternatives with AEC-Q101 qualification. Both parts maintain identical electrical specifications to the original MMSZ5250B with 25 Ohms impedance and 100 nA reverse leakage. SZMMSZ5250BT1G has 17,400 pieces in stock; SZMMSZ5250ET1G has 3,714 pieces available.

For Tighter Voltage Tolerance:

MMSZ5250CT1G (onsemi) offers ±2% voltage tolerance compared to the original ±5%, with all other electrical parameters identical. This part is active with ROHS3 compliance and 3,200 pieces in stock. Selection is appropriate when circuit design requires enhanced voltage regulation precision.

For General-Purpose Applications with Lower Impedance:

MMSZ20T1G and SZMMSZ20T1G (onsemi) both feature 55 Ohms maximum impedance and lower reverse leakage (50 nA @ 14 V) compared to the original 25 Ohms and 100 nA. These parts are suitable for applications where impedance variation is acceptable. MMSZ20T1G is standard grade with 2,042 pieces in stock; SZMMSZ20T1G is automotive-qualified with 20,300 pieces available.

For Superior Reverse Leakage Performance:

MMSZ4707T1G (onsemi) provides 10 nA reverse leakage at 15.2 V, significantly lower than the original 100 nA. This part is active with ROHS3 compliance and 20,400 pieces in stock, suitable for low-leakage circuit requirements.

For Extended Temperature Range:

MMSZ5250B-13-F (Diodes Incorporated) extends the operating temperature range to -65°C to 150°C compared to the original -55°C to 150°C. Power dissipation is reduced to 370 mW. This part is active with ROHS3 compliance and 743 pieces in stock.

Frequently Asked Questions (FAQ)

Q: Can MMSZ5250BT1G be used as a direct replacement for MMSZ5250B?

A: Yes. MMSZ5250BT1G maintains identical electrical specifications including 20 V nominal Zener voltage, ±5% tolerance, 500 mW power rating, 25 Ohms maximum impedance, and 100 nA reverse leakage current at 15 V. The primary difference is product status (active versus obsolete) and packaging format (Cut Tape & Digi-Reel versus original packaging). Both are SOD-123 surface mount packages.

Q: What is the difference between MMSZ20T1G and MMSZ5250BT1G?

A: Both parts share identical nominal Zener voltage (20 V), tolerance (±5%), power rating (500 mW), forward voltage (900 mV @ 10 mA), and operating temperature range (-55°C to 150°C). The key difference is impedance: MMSZ20T1G has 55 Ohms maximum impedance, while MMSZ5250BT1G has 25 Ohms. MMSZ20T1G also exhibits lower reverse leakage (50 nA @ 14 V versus 100 nA @ 15 V). Selection depends on circuit impedance requirements.

Q: Are automotive-grade parts (SZMMSZ5250BT1G, SZMMSZ5250ET1G) suitable for non-automotive applications?

A: Yes. Automotive-grade parts with AEC-Q101 qualification meet or exceed standard commercial specifications. These parts maintain identical electrical parameters to the original MMSZ5250B and are suitable for any application requiring the specified 20 V, 500 mW Zener diode characteristics. Automotive qualification indicates enhanced reliability and process control.

Q: Why does MMSZ5250CT1G have a ±2% tolerance instead of ±5%?

A: MMSZ5250CT1G is a parametric equivalent with tighter voltage tolerance. The ±2% tolerance provides enhanced voltage regulation precision compared to the original ±5%. All other electrical specifications remain identical. This part is appropriate for applications requiring more precise Zener voltage control.

Q: What is the significance of the "T1G" suffix in part numbers like MMSZ5250BT1G?

A: The "T1G" suffix indicates the packaging and manufacturing date code format used by onsemi. These parts are available in Tape & Reel or Cut Tape & Digi-Reel packaging formats suitable for automated assembly processes. The suffix does not affect electrical specifications.

Q: Can MMSZ5250B-13-F (Diodes Incorporated) be used in place of MMSZ5250B?

A: MMSZ5250B-13-F is functionally compatible for most applications. It maintains the 20 V nominal Zener voltage, ±5% tolerance, and 900 mV forward voltage. However, the power rating is reduced to 370 mW (versus 500 mW), and the operating temperature range is extended to -65°C to 150°C (versus -55°C to 150°C). Selection requires confirmation that the reduced power dissipation rating is acceptable for the intended circuit.

Q: What is the difference between standard and automotive-grade Zener diodes?

A: Automotive-grade parts (identified by "SZ" prefix and AEC-Q101 qualification) undergo enhanced qualification testing and process controls to meet automotive reliability standards. Electrical specifications remain identical to standard-grade equivalents. Automotive-grade parts are suitable for any application but are typically specified for automotive, industrial, or mission-critical environments.

Q: Are all substitute parts ROHS3 compliant?

A: All active substitute parts listed are ROHS3 compliant. The original MMSZ5250B does not specify RoHS status due to its obsolete classification. ROHS3 compliance indicates the parts are free from restricted substances including lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls, and polybrominated diphenyl ethers.

Q: What packaging options are available for 20 V, 500 mW Zener diodes?

A: Available packaging formats include Tape & Reel (TR), Cut Tape (CT) & Digi-Reel, and standard component packaging. All substitute parts maintain SOD-123 surface mount package type. Packaging selection depends on assembly process requirements and volume considerations. Tape & Reel format is standard for high-volume automated assembly; Cut Tape & Digi-Reel is suitable for mixed-volume production.

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