ZMM5256B-7 Equivalent & Substitute Parts

Part Overview

The ZMM5256B-7 is a 30 V, 500 mW Zener diode manufactured by Diodes Incorporated in Mini MELF surface mount packaging (DO-213AC). This component is classified as obsolete, indicating discontinuation from active production. Equivalent and substitute parts are necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for applications requiring 30 V Zener regulation at 500 mW power dissipation.

Key Parameters

Parameter	Value
Voltage - Zener (Nom)	30 V
Tolerance	±5%
Power - Max	500 mW
Impedance (Max)	49 Ohms
Current - Reverse Leakage @ Vr	100 nA @ 23 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 ZMM5256B-7 is determined by the following critical electrical and mechanical parameters:

Electrical Equivalence Criteria:

Zener voltage: 30 V nominal
Power dissipation: 500 mW maximum
Impedance: 49 Ohms maximum
Reverse leakage current: 100 nA @ specified voltage
Operating temperature range: -65°C to 175°C minimum

Mechanical Compatibility Criteria:

Surface mount mounting type
Package compatibility: DO-213AC (Mini MELF), SOD-123, or DO-213AB (MELF) footprints

Compliance Criteria:

RoHS3 compliance preferred for new designs
Moisture sensitivity level: 1 (Unlimited)

Substitute parts are grouped into two categories: direct electrical equivalents with alternative packaging (MMSZ5256B-7-F in SOD-123, TLZ series in SOD-80), and functional equivalents with tolerance variations (CDLL5256 and CDLL5256A with ±20% and ±10% tolerances respectively). The 1N5256BUR-1 provides electrical equivalence with extended temperature capability but differs in RoHS compliance status.

Parameter Comparison

Part Number	Manufacturer	Vz (Nom)	Tolerance	Power (Max)	Zzt (Max)	Package	Status	RoHS
ZMM5256B-7	Diodes Inc.	30 V	±5%	500 mW	49 Ω	DO-213AC	Obsolete	ROHS3
MMSZ5256B-7-F	Diodes Inc.	30 V	±5%	500 mW	49 Ω	SOD-123	Active	ROHS3
1N5256BUR-1	Microchip	30 V	±5%	500 mW	49 Ω	DO-213AA	Active	Non-compliant
CDLL5256	Microchip	30 V	±20%	—	49 Ω	DO-213AB	Active	Non-compliant
CDLL5256A	Microchip	30 V	±10%	—	49 Ω	DO-213AB	Active	Non-compliant
TLZ30A-GS08	Vishay	30 V	—	500 mW	80 Ω	SOD-80	Active	ROHS3
TLZ30A-GS18	Vishay	30 V	—	500 mW	80 Ω	SOD-80	Active	ROHS3
TLZ30B-GS08	Vishay	30 V	—	500 mW	80 Ω	SOD-80	Active	ROHS3
TLZ30B-GS18	Vishay	30 V	—	500 mW	80 Ω	SOD-80	Active	ROHS3
TLZ30C-GS08	Vishay	30 V	—	500 mW	80 Ω	SOD-80	Active	ROHS3
TLZ30C-GS18	Vishay	30 V	—	500 mW	80 Ω	SOD-80	Active	ROHS3

Engineering Selection Recommendations

Primary Recommendation: MMSZ5256B-7-F

The MMSZ5256B-7-F from Diodes Incorporated is the manufacturer-recommended direct equivalent. It maintains identical electrical specifications (30 V, ±5% tolerance, 500 mW, 49 Ω impedance) and RoHS3 compliance. The primary difference is packaging format (SOD-123 versus DO-213AC Mini MELF). This part is active in production with substantial inventory availability (32,100 units), ensuring long-term supply continuity.

Secondary Recommendation: TLZ30 Series (Vishay)

The TLZ30A-GS08, TLZ30A-GS18, TLZ30B-GS08, TLZ30B-GS18, TLZ30C-GS08, and TLZ30C-GS18 from Vishay General Semiconductor provide electrical equivalence with 30 V nominal voltage and 500 mW power rating. These parts maintain RoHS3 compliance and operate across the full -65°C to 175°C temperature range. The impedance specification differs (80 Ω maximum versus 49 Ω), and tolerance information is not specified. All variants are active in production. Selection among variants depends on tape reel configuration requirements (GS08 or GS18 designations).

Alternative Consideration: 1N5256BUR-1

The 1N5256BUR-1 from Microchip Technology provides electrical equivalence with identical voltage, tolerance, power, and impedance specifications. Operating temperature extends to 175°C. However, this part is RoHS non-compliant, limiting applicability to legacy or non-regulated applications. Use is restricted to designs where RoHS compliance is not required.

Tolerance-Relaxed Options: CDLL5256 and CDLL5256A

The CDLL5256 (±20% tolerance) and CDLL5256A (±10% tolerance) from Microchip Technology are functional alternatives where tighter voltage tolerance is not critical. Both are active in production and operate across -65°C to 175°C. RoHS non-compliance applies to both variants. Power dissipation specification is not provided for these parts.

Frequently Asked Questions (FAQ)

Q: Can MMSZ5256B-7-F directly replace ZMM5256B-7 without circuit modification?

A: MMSZ5256B-7-F provides electrical equivalence with identical voltage, tolerance, power, and impedance specifications. The primary difference is packaging format (SOD-123 versus DO-213AC Mini MELF). PCB footprint modification is required. Electrical performance is equivalent.

Q: What is the difference between TLZ30A, TLZ30B, and TLZ30C variants?

A: All three variants (TLZ30A, TLZ30B, TLZ30C) provide identical electrical specifications: 30 V nominal voltage, 500 mW power, 80 Ω impedance, and -65°C to 175°C operating range. Variants differ in reverse leakage current specifications at different voltage points (TLZ30A at 25.6 V, TLZ30B at 26.3 V, TLZ30C at 26.9 V). Selection depends on application leakage current requirements.

Q: Why do CDLL5256 and CDLL5256A have different tolerance specifications?

A: CDLL5256 is specified with ±20% tolerance, while CDLL5256A is specified with ±10% tolerance. Both maintain 30 V nominal voltage and 49 Ω impedance. CDLL5256A provides tighter voltage regulation where application requirements demand improved accuracy.

Q: Is RoHS compliance critical for substitute part selection?

A: RoHS3 compliance is mandatory for applications subject to European Union regulations or equivalent environmental standards. MMSZ5256B-7-F and all TLZ series parts are RoHS3 compliant. The 1N5256BUR-1 and CDLL series parts are RoHS non-compliant and are restricted to legacy or non-regulated applications.

Q: What packaging options are available for 30 V, 500 mW Zener diodes?

A: Available packages include DO-213AC (Mini MELF), SOD-123, SOD-80 (Mini MELF), and DO-213AB (MELF). Package selection depends on PCB layout constraints and manufacturing equipment capabilities. All packages provide surface mount mounting.

Q: Can TLZ30 series parts be used in applications requiring 49 Ω impedance specification?

A: TLZ30 series parts specify 80 Ω maximum impedance, which differs from the ZMM5256B-7 specification of 49 Ω. Applications with impedance-sensitive circuits may require circuit analysis to confirm compatibility. Higher impedance may affect voltage regulation performance in specific circuit topologies.

Q: What is the inventory status of substitute parts?

A: MMSZ5256B-7-F has 32,100 units in stock. TLZ30C-GS08 has 10,200 units. Other TLZ variants range from 693 to 1,900 units. CDLL5256A has 1,024 units. 1N5256BUR-1 has 937 units. CDLL5256 has 749 units. Inventory levels support immediate procurement for all substitute options.

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