ZMM5248B-7 Equivalent & Substitute Parts

Part Overview

The ZMM5248B-7 is a Zener diode rated at 18 V, 500 mW, manufactured by Diodes Incorporated in Mini MELF surface mount packaging. This component is classified as obsolete, necessitating identification of active equivalent and substitute parts for ongoing design requirements and production continuity. Substitute parts must maintain electrical equivalence across zener voltage, power dissipation, and thermal operating range while accommodating alternative package configurations.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	18	V
Tolerance	±5%	-
Power - Max	500	mW
Impedance (Max)	21	Ohms
Current - Reverse Leakage @ Vr	100 nA @ 14 V	-
Voltage - Forward (Vf) (Max) @ If	1.5 V @ 200 mA	-
Operating Temperature	-65°C ~ 175°C	-
Mounting Type	Surface Mount	-
Package / Case	DO-213AC, MINI-MELF, SOD-80	-
RoHS Status	ROHS3 Compliant	-
Moisture Sensitivity Level	1 (Unlimited)	-

Substitute Part Grouping Explanation

Substitution of the ZMM5248B-7 is determined by the following critical parameters:

Electrical Equivalence Requirements:

Zener voltage: 18 V nominal
Power dissipation: 500 mW maximum
Impedance: 21 Ohms maximum
Reverse leakage current: 100 nA @ 14 V
Operating temperature range: -65°C to 175°C minimum

Mechanical Compatibility:

Surface mount mounting type
Package options: DO-213AC (Mini MELF/SOD-80), SOD-123, or DO-213AB (MELF)

Substitute parts are grouped into two categories based on package configuration:

Category 1: Mini MELF/SOD-80 Package (Direct Package Match)

TLZ18A-GS08, TLZ18A-GS18, TLZ18B-GS08, TLZ18B-GS18 (Vishay)

Category 2: Alternative Surface Mount Packages (Electrical Equivalence with Package Change)

MMSZ5248B-7-F (SOD-123 package)
1N5248BUR-1 (DO-213AA package)
CDLL5248, CDLL5248A, CDLL5248B (DO-213AB package)

Parameter Comparison

Part Number	Manufacturer	Vz (Nom)	Tolerance	Power (Max)	Zzt (Max)	Vf (Max) @ If	Temp Range	Package	Status
ZMM5248B-7	Diodes Inc.	18 V	±5%	500 mW	21 Ω	1.5 V @ 200 mA	-65 to 175°C	Mini MELF	Obsolete
MMSZ5248B-7-F	Diodes Inc.	18 V	±5%	500 mW	21 Ω	900 mV @ 10 mA	-65 to 150°C	SOD-123	Active
1N5248BUR-1	Microchip	18 V	±5%	500 mW	21 Ω	1.1 V @ 200 mA	-65 to 175°C	DO-213AA	Active
CDLL5248	Microchip	18 V	±20%	-	21 Ω	1.1 V @ 200 mA	-65 to 175°C	DO-213AB	Active
CDLL5248A	Microchip	18 V	±10%	-	21 Ω	1.1 V @ 200 mA	-65 to 175°C	DO-213AB	Active
CDLL5248B	Microchip	18 V	±5%	-	21 Ω	1.1 V @ 200 mA	-65 to 175°C	DO-213AB	Active
TLZ18A-GS08	Vishay	18 V	-	500 mW	23 Ω	1.5 V @ 200 mA	-65 to 175°C	SOD-80	Active
TLZ18A-GS18	Vishay	18 V	-	500 mW	23 Ω	1.5 V @ 200 mA	-65 to 175°C	SOD-80	Active
TLZ18B-GS08	Vishay	18 V	-	500 mW	23 Ω	1.5 V @ 200 mA	-65 to 175°C	SOD-80	Active
TLZ18B-GS18	Vishay	18 V	-	500 mW	23 Ω	1.5 V @ 200 mA	-65 to 175°C	SOD-80	Active

Engineering Selection Recommendations

Primary Recommendation: Vishay TLZ18B-GS18

The TLZ18B-GS18 provides direct package compatibility with the ZMM5248B-7 in SOD-80 Mini MELF configuration. This part maintains identical electrical specifications (18 V, 500 mW, 23 Ω impedance) and operating temperature range (-65°C to 175°C). The part is active with ROHS3 compliance and REACH unaffected status. Inventory availability is 1,160 units.

Secondary Recommendation: Diodes Incorporated MMSZ5248B-7-F

The MMSZ5248B-7-F is manufactured by the same supplier as the original part, ensuring design continuity. It maintains ±5% tolerance and 500 mW power rating with identical impedance. The SOD-123 package requires PCB layout modification. Operating temperature range is -65°C to 150°C, which is acceptable for most applications within the original -65°C to 175°C specification. The part is active with ROHS3 compliance. Inventory availability is 77,400 units.

Tertiary Recommendation: Microchip 1N5248BUR-1

The 1N5248BUR-1 maintains full electrical equivalence with ±5% tolerance, 500 mW power, and -65°C to 175°C operating range. The DO-213AA package is compatible with Mini MELF footprints. The part is active but RoHS non-compliant. Inventory availability is 667 units.

Alternative for Tolerance-Relaxed Applications: Microchip CDLL5248B

The CDLL5248B provides ±5% tolerance matching with 18 V zener voltage and -65°C to 175°C operating range. The DO-213AB MELF package accommodates the original footprint. The part is active but RoHS non-compliant. Inventory availability is 678 units.

Frequently Asked Questions (FAQ)

Q: Can the ZMM5248B-7 be directly replaced with the MMSZ5248B-7-F?

A: Electrical substitution is valid. Both parts share 18 V nominal zener voltage, ±5% tolerance, 500 mW power rating, and 21 Ω impedance. The MMSZ5248B-7-F operates to 150°C versus the original 175°C maximum. PCB layout modification is required due to SOD-123 package versus Mini MELF. Thermal design must account for the reduced upper operating temperature limit.

Q: What is the difference between the Vishay TLZ18A and TLZ18B series?

A: Both series provide identical electrical performance at 18 V, 500 mW with SOD-80 Mini MELF packaging. The TLZ18B-GS variants specify reverse leakage current at 16 V, while TLZ18A-GS variants specify at 15.4 V. Both meet the original 100 nA @ 14 V specification. Selection between variants depends on specific application leakage requirements.

Q: Are the Microchip CDLL5248 variants interchangeable?

A: The CDLL5248, CDLL5248A, and CDLL5248B share identical 18 V zener voltage, 21 Ω impedance, and -65°C to 175°C operating range. Tolerance specifications differ: CDLL5248 (±20%), CDLL5248A (±10%), CDLL5248B (±5%). Selection depends on circuit tolerance requirements. The CDLL5248B matches the original ±5% specification.

Q: What are the package compatibility considerations?

A: The original ZMM5248B-7 uses Mini MELF (SOD-80) packaging. Direct package substitutes include Vishay TLZ18 series. Alternative packages require PCB modification: SOD-123 (MMSZ5248B-7-F) is smaller; DO-213AA and DO-213AB are larger MELF variants. Footprint verification is mandatory before design implementation.

Q: Does the operating temperature range affect substitution validity?

A: The original part specifies -65°C to 175°C. The MMSZ5248B-7-F operates to 150°C maximum. If the application requires operation above 150°C, this substitute is invalid. All other recommended substitutes maintain the full -65°C to 175°C range.

Q: What is the significance of RoHS compliance status?

A: The original ZMM5248B-7 is ROHS3 compliant. The Vishay TLZ18 series and MMSZ5248B-7-F maintain ROHS3 compliance. Microchip CDLL and 1N5248BUR variants are RoHS non-compliant. For applications requiring RoHS compliance, select from Diodes Incorporated or Vishay options.

Q: How do impedance differences affect circuit performance?

A: The original part specifies 21 Ω maximum impedance. Vishay TLZ18 series specifies 23 Ω maximum. This 2 Ω difference affects dynamic impedance characteristics at high frequencies. For precision voltage regulation circuits, verify that the higher impedance remains within circuit tolerance margins.

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