MMSZ5255B Equivalent & Substitute Parts

Part Overview

The MMSZ5255B is a 28 V, 500 mW Zener diode manufactured by onsemi in SOD-123 surface mount packaging. This component is classified as obsolete, which necessitates identification of equivalent and substitute parts for ongoing design requirements and production continuity. 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.

Key Parameters

Parameter	Value
Voltage - Zener (Nom)	28 V
Tolerance	±5%
Power - Max	500 mW
Impedance (Max)	44 Ohms
Current - Reverse Leakage @ Vr	100 nA @ 21 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 MMSZ5255B is determined by the following critical parameters: nominal Zener voltage (28 V), maximum power dissipation (500 mW), voltage tolerance (±5%), impedance (44 Ohms maximum), reverse leakage current (100 nA @ 21 V), forward voltage drop (900 mV @ 10 mA), and surface mount SOD-123 packaging. Parts are grouped into three categories based on their relationship to the main part:

Direct Manufacturer Substitutes maintain identical electrical specifications and are sourced from the original manufacturer onsemi. These parts differ only in packaging format (Tape & Reel) or product status (Active vs. Obsolete).

Parametric Equivalents meet all critical electrical specifications but may originate from different manufacturers or include additional qualifications such as automotive-grade certification (AEC-Q101).

Similar Parts share the same nominal Zener voltage and package type but exhibit variations in power rating, impedance, or reverse leakage current. These parts are suitable only when application requirements permit tolerance of the specified parameter deviations.

Parameter Comparison

Part Number	Manufacturer	Vz (Nom)	Tolerance	Power (Max)	Zzt (Max)	Leakage @ Vr	Vf (Max) @ If	Temp Range	Package	Status
MMSZ5255B	onsemi	28 V	±5%	500 mW	44 Ω	100 nA @ 21 V	900 mV @ 10 mA	-55°C ~ 150°C	SOD-123	Obsolete
MMSZ5255BT1G	onsemi	28 V	±5%	500 mW	44 Ω	100 nA @ 21 V	900 mV @ 10 mA	-55°C ~ 150°C	SOD-123	Active
MMSZ5255ET1G	onsemi	28 V	±5%	500 mW	44 Ω	100 nA @ 21 V	900 mV @ 10 mA	-55°C ~ 150°C	SOD-123	Active
SZMMSZ5255BT1G	onsemi	28 V	±5%	500 mW	44 Ω	100 nA @ 21 V	900 mV @ 10 mA	-55°C ~ 150°C	SOD-123	Active
MMSZ5255B-7-F	Diodes Incorporated	28 V	±5%	500 mW	44 Ω	100 nA @ 21 V	900 mV @ 10 mA	-65°C ~ 150°C	SOD-123	Active
BZT52H-C27,115	Nexperia USA Inc.	27 V	±5%	375 mW	40 Ω	50 nA @ 18.9 V	900 mV @ 10 mA	-65°C ~ 150°C	SOD-123F	Active
CMHZ5255B TR PBFREE	Central Semiconductor Corp	28 V	±5%	500 mW	44 Ω	100 nA @ 21 V	900 mV @ 10 mA	-65°C ~ 150°C	SOD-123	Active
CZRW5255B-G	Comchip Technology	28 V	±5%	350 mW	44 Ω	100 nA @ 18 V	900 mV @ 10 mA	-65°C ~ 150°C	SOD-123	Active
DDZ28-7	Diodes Incorporated	28 V	±3%	500 mW	55 Ω	50 nA @ 23 V	900 mV @ 10 mA	-65°C ~ 150°C	SOD-123	Active
DDZ9712-7	Diodes Incorporated	28 V	±5%	500 mW	Not specified	50 nA @ 21.2 V	900 mV @ 10 mA	-65°C ~ 150°C	SOD-123	Active
MMSZ4715-TP	Micro Commercial Co	36 V	±5%	500 mW	Not specified	10 nA @ 27.3 V	950 mV @ 10 mA	-55°C ~ 150°C	SOD-123	Active

Engineering Selection Recommendations

Primary Substitutes (Direct Replacement)

MMSZ5255BT1G and MMSZ5255ET1G are direct onsemi substitutes with identical electrical specifications to the MMSZ5255B. Both parts are Active status and suitable for immediate replacement. MMSZ5255BT1G is available in Tape & Reel packaging format. MMSZ5255ET1G provides an alternative sourcing option within the same manufacturer series.

Automotive-Grade Alternative

SZMMSZ5255BT1G is an onsemi automotive-grade variant qualified to AEC-Q101 standard. This part maintains identical electrical specifications and is suitable for applications requiring automotive qualification. Product status is Active with substantial inventory availability.

Cross-Manufacturer Equivalent

MMSZ5255B-7-F from Diodes Incorporated provides parametric equivalence with identical electrical specifications. This part extends the operating temperature range to -65°C and holds Active status. RoHS3 compliance is confirmed.

Alternative Sourcing with Specification Variations

CMHZ5255B TR PBFREE from Central Semiconductor Corp matches all critical electrical parameters and extends the operating temperature range to -65°C. This part is RoHS3 compliant and Active.

DDZ28-7 from Diodes Incorporated provides tighter voltage tolerance (±3% versus ±5%) and is suitable for applications requiring improved voltage regulation accuracy. Impedance is specified at 55 Ohms maximum, which is higher than the main part. Reverse leakage current is reduced to 50 nA @ 23 V.

Parts with Reduced Power Rating

CZRW5255B-G from Comchip Technology maintains the 28 V nominal voltage and SOD-123 package but reduces maximum power dissipation to 350 mW. This part is suitable only for applications where the lower power rating is acceptable.

Parts with Voltage Deviation

BZT52H-C27,115 from Nexperia USA Inc. specifies 27 V nominal Zener voltage (versus 28 V) and reduces maximum power to 375 mW. This part includes automotive-grade qualification (AEC-Q101) and is suitable only when the 1 V voltage deviation is acceptable to the application.

MMSZ4715-TP from Micro Commercial Co specifies 36 V nominal Zener voltage and is not suitable as a direct substitute for 28 V applications.

Frequently Asked Questions (FAQ)

Q: Can MMSZ5255BT1G be used as a direct replacement for MMSZ5255B?

A: Yes. MMSZ5255BT1G is a direct onsemi substitute with identical electrical specifications: 28 V nominal Zener voltage, ±5% tolerance, 500 mW maximum power, 44 Ohms impedance, and SOD-123 packaging. The primary difference is packaging format (Tape & Reel) and Active product status versus the obsolete MMSZ5255B.

Q: What is the difference between MMSZ5255BT1G and SZMMSZ5255BT1G?

A: Both parts maintain identical electrical specifications. SZMMSZ5255BT1G is an automotive-grade variant qualified to AEC-Q101 standard, making it suitable for automotive applications. Selection depends on whether automotive qualification is required.

Q: Is DDZ28-7 a suitable substitute?

A: DDZ28-7 is suitable when tighter voltage tolerance is beneficial. It specifies ±3% tolerance versus ±5% for the MMSZ5255B, providing improved voltage regulation accuracy. However, impedance is specified at 55 Ohms maximum (versus 44 Ohms), and reverse leakage current is reduced to 50 nA @ 23 V. These variations are acceptable in most applications.

Q: Can BZT52H-C27,115 replace MMSZ5255B?

A: BZT52H-C27,115 is not a direct substitute. It specifies 27 V nominal Zener voltage (1 V lower than the 28 V requirement) and reduces maximum power dissipation to 375 mW. Use this part only when the application can tolerate the voltage deviation and lower power rating. The part includes automotive-grade qualification (AEC-Q101).

Q: What is the significance of the SOD-123F package variant?

A: BZT52H-C27,115 uses SOD-123F packaging, which differs from the standard SOD-123 package used by the MMSZ5255B and most substitutes. Verify PCB footprint compatibility before selection.

Q: Why is MMSZ4715-TP listed as a similar part?

A: MMSZ4715-TP is included for reference only. It specifies 36 V nominal Zener voltage and is not suitable as a substitute for 28 V applications. It is listed because it shares the same 500 mW power rating and SOD-123 package.

Q: Are all substitute parts RoHS3 compliant?

A: All substitute parts listed are confirmed RoHS3 compliant. The original MMSZ5255B does not specify RoHS status in the provided data.

Q: What is the temperature range difference between MMSZ5255B and MMSZ5255B-7-F?

A: MMSZ5255B specifies -55°C to 150°C operating temperature, while MMSZ5255B-7-F extends the lower limit to -65°C. This extended range is beneficial for applications requiring operation in colder environments.

Q: Can I use CMHZ5255B TR PBFREE as a direct replacement?

A: Yes. CMHZ5255B TR PBFREE maintains all critical electrical specifications: 28 V nominal voltage, ±5% tolerance, 500 mW power, 44 Ohms impedance, and SOD-123 packaging. It extends the operating temperature range to -65°C and is RoHS3 compliant.

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