MMBZ5237B-7 Equivalent & Substitute Parts

Part Overview

The MMBZ5237B-7 is a Zener diode rated at 8.2 V nominal voltage with 350 mW maximum power dissipation in a surface mount SOT-23-3 package. Manufactured by Diodes Incorporated, this component is classified as discontinued at DiGi Electronics, necessitating identification of equivalent and substitute parts for ongoing design requirements and production continuity. The part operates across a temperature range of -65°C to 150°C and maintains RoHS non-compliance status with unlimited moisture sensitivity rating.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	8.2	V
Tolerance	±5%	—
Power - Max	350	mW
Impedance (Max)	8	Ohms
Current - Reverse Leakage @ Vr	3	µA @ 6.5 V
Voltage - Forward (Vf) (Max) @ If	900	mV @ 10 mA
Operating Temperature	-65 to 150	°C
Mounting Type	Surface Mount	—
Package / Case	TO-236-3, SC-59, SOT-23-3	—

Substitute Part Grouping Explanation

Substitution of the MMBZ5237B-7 is determined by the following critical parameters:

Primary Substitution Criteria:

Zener voltage: 8.2 V nominal
Package type: SOT-23-3 (TO-236-3, SC-59)
Mounting: Surface mount
Operating temperature range: -65°C to 150°C minimum
Forward voltage: 900 mV @ 10 mA maximum

Secondary Substitution Criteria:

Power dissipation rating (350 mW preferred; lower ratings acceptable with design verification)
Impedance characteristics (8 Ohms preferred; up to 15 Ohms acceptable)
Reverse leakage current (3 µA @ 6.5 V preferred; up to 700 nA @ 5 V acceptable)
Voltage tolerance (±5% preferred; ±6% or ±1% acceptable)

Substitute parts are grouped into two categories: Parametric Equivalents (matching all critical specifications) and Functional Equivalents (meeting core electrical requirements with minor parameter variations).

Parameter Comparison

Part Number	Manufacturer	Vz (V)	Tolerance	Power (mW)	Zzt (Ohms)	Vf @ 10mA (mV)	Temp Range (°C)	Package	Status
MMBZ5237B-7	Diodes Inc.	8.2	±5%	350	8	900	-65 to 150	SOT-23-3	Discontinued
MMBZ5237B-7-F	Diodes Inc.	8.2	±5%	350	8	900	-65 to 150	SOT-23-3	Active
BZX84C8V2-7-F	Diodes Inc.	8.2	±6%	300	15	900	-65 to 150	SOT-23-3	Active
BZX84-A8V2,215	Nexperia USA Inc.	8.2	±1%	250	15	900	-65 to 150	TO-236AB	Active
BZX84C8V2-TP	Micro Commercial Co	8.2	±5%	350	15	900	-55 to 150	SOT-23	Active
MMBZ5237BLT1G	onsemi	8.2	±5%	225	8	900	-65 to 150	SOT-23-3	Active
SZBZX84C8V2LT1G	onsemi	8.2	±5%	225	15	900	-65 to 150	SOT-23-3	Active
SZMMBZ5237BLT1G	onsemi	8.2	±5%	225	8	900	-65 to 150	SOT-23-3	Active
CMPZ5237B TR PBFREE	Central Semiconductor Corp	8.2	±5%	350	8	900	-65 to 150	SOT-23	Active

Engineering Selection Recommendations

Parametric Equivalent (Direct Replacement):

MMBZ5237B-7-F is the primary direct replacement. This part maintains identical electrical specifications (8.2 V, ±5%, 350 mW, 8 Ohms impedance) and package configuration (SOT-23-3). The part is manufactured by Diodes Incorporated with active product status and ROHS3 compliance. Inventory availability is 23,400 units.

Functional Equivalents with Reduced Power Rating:

MMBZ5237BLT1G, SZBZX84C8V2LT1G, and SZMMBZ5237BLT1G are manufactured by onsemi with 225 mW maximum power dissipation. These parts maintain the 8.2 V nominal voltage, ±5% tolerance, SOT-23-3 package, and full operating temperature range. SZMMBZ5237BLT1G and SZBZX84C8V2LT1G carry AEC-Q101 automotive qualification. Selection of these parts requires verification that circuit power dissipation does not exceed 225 mW.

Functional Equivalents with Impedance Variation:

BZX84C8V2-7-F (Diodes Incorporated, 300 mW) and BZX84C8V2-TP (Micro Commercial Co, 350 mW) feature 15 Ohms maximum impedance compared to the original 8 Ohms. Both maintain 8.2 V nominal voltage and SOT-23-3 package. BZX84C8V2-TP operates at -55°C minimum temperature. These parts are suitable where impedance variation is acceptable within circuit design margins.

Automotive-Grade Alternative:

BZX84-A8V2,215 (Nexperia USA Inc.) provides AEC-Q101 qualification with ±1% voltage tolerance and 250 mW power rating. This part is specified in TO-236AB package with 15 Ohms impedance. Selection is appropriate for automotive applications requiring tighter voltage tolerance.

RoHS Compliance Consideration:

All substitute parts listed carry ROHS3 compliance status, whereas the original MMBZ5237B-7 is RoHS non-compliant. This distinction is significant for applications subject to RoHS regulatory requirements.

Frequently Asked Questions (FAQ)

Q: Can MMBZ5237B-7-F be used as a direct replacement for MMBZ5237B-7?

A: Yes. MMBZ5237B-7-F is a parametric equivalent with identical electrical specifications and package configuration. The primary difference is packaging format (Tape & Reel versus cut tape) and active product status. Both parts are manufactured by Diodes Incorporated.

Q: What is the difference between SOT-23-3 and TO-236AB packages?

A: SOT-23-3 and TO-236AB are equivalent package designations for the same physical form factor. Both refer to a three-terminal surface mount package with identical pin spacing and dimensions. Parts specified in either designation are mechanically and electrically interchangeable.

Q: Can I use a 225 mW rated part in place of the 350 mW original?

A: Substitution with lower power-rated parts (MMBZ5237BLT1G, SZBZX84C8V2LT1G, SZMMBZ5237BLT1G) is permissible only when circuit design ensures that power dissipation in the Zener diode does not exceed 225 mW under all operating conditions, including worst-case scenarios.

Q: What does ±5% voltage tolerance mean?

A: Voltage tolerance specifies the acceptable deviation of the Zener voltage from the nominal 8.2 V rating. ±5% tolerance indicates the actual voltage will fall between 7.79 V and 8.61 V. Tighter tolerances (such as ±1% in BZX84-A8V2,215) provide narrower voltage ranges.

Q: Are automotive-qualified parts required for this application?

A: Automotive qualification (AEC-Q101) is required only for applications subject to automotive industry standards. SZBZX84C8V2LT1G, SZMMBZ5237BLT1G, and BZX84-A8V2,215 carry this qualification. Standard industrial applications do not require this certification.

Q: What is the significance of impedance (Zzt) variation?

A: Impedance affects the Zener diode's dynamic response and voltage regulation characteristics. Lower impedance (8 Ohms) provides better voltage stability under load changes. Higher impedance (15 Ohms) may result in greater voltage variation. Selection depends on circuit requirements for voltage regulation performance.

Q: Why is the original part discontinued?

A: Product discontinuation at DiGi Electronics reflects supplier lifecycle management decisions. The MMBZ5237B-7 remains functionally viable; however, active alternatives with equivalent or superior specifications are available from multiple manufacturers.

Q: Can I mix different manufacturers' parts in the same circuit?

A: Yes. All listed substitute parts meet the same electrical specifications for Zener voltage, forward voltage, and operating temperature range. Mixing manufacturers is acceptable provided all parts meet the specific electrical requirements of the circuit design.

Q: What is the difference between reverse leakage current specifications?

A: Reverse leakage current (3 µA @ 6.5 V versus 700 nA @ 5 V) indicates the small current flowing through the Zener diode in reverse bias. Lower leakage current reduces power consumption in standby conditions. The difference is negligible for most applications.

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