MMBZ5259C-E3-18 Equivalent & Substitute Parts

Part Overview

The MMBZ5259C-E3-18 is a Zener diode rated at 39 V nominal voltage with 225 mW maximum power dissipation in a surface mount SOT-23-3 package. Manufactured by Vishay General Semiconductor - Diodes Division, this component is classified as obsolete. Due to its obsolete status and limited availability relative to active alternatives, equivalent substitute parts with matching or superior electrical characteristics are necessary for ongoing design support and production continuity.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	39	V
Tolerance	±2%	—
Power - Max	225	mW
Impedance (Max)	80	Ohms
Current - Reverse Leakage @ Vr	100 nA @ 30 V	—
Operating Temperature Range	-55 to 150	°C
Mounting Type	Surface Mount	—
Package / Case	TO-236-3, SC-59, SOT-23-3	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the MMBZ5259C-E3-18 is determined by the following critical parameters:

Primary Matching Criteria:

Zener voltage: 39 V nominal
Package type: SOT-23-3 (TO-236-3, SC-59)
Mounting: Surface mount
Reverse leakage current: 100 nA @ 30 V or equivalent test condition

Secondary Compatibility Criteria:

Power dissipation: Equal to or greater than 225 mW
Impedance: 80 Ohms or lower
Operating temperature range: Minimum -55°C to 150°C
RoHS3 compliance and MSL 1 rating

Tolerance Consideration: The main part specifies ±2% tolerance. Substitute parts with ±5% tolerance remain functionally compatible in applications where the tighter tolerance is not a circuit-critical requirement, as the nominal voltage remains 39 V.

Parameter Comparison

Parameter	MMBZ5259C-E3-18 (Main)	CMPZ5259B BK PBFREE	CZRT55C39-G	MMBZ5259BLT1G
Manufacturer	Vishay General Semiconductor	Central Semiconductor Corp	Comchip Technology	onsemi
Voltage - Zener (Nom)	39 V	39 V	39 V	39 V
Tolerance	±2%	±5%	±5%	±5%
Power - Max	225 mW	350 mW	350 mW	225 mW
Impedance (Max)	80 Ohms	80 Ohms	130 Ohms	80 Ohms
Current - Reverse Leakage @ Vr	100 nA @ 30 V	100 nA @ 30 V	100 nA @ 27.3 V	100 nA @ 30 V
Operating Temperature Range	-55 to 150°C	-65 to 150°C	-65 to 150°C	-65 to 150°C
Package / Case	TO-236-3, SC-59, SOT-23-3	TO-236-3, SC-59, SOT-23-3	TO-236-3, SC-59, SOT-23-3	TO-236-3, SC-59, SOT-23-3
Product Status	Obsolete	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

MMBZ5259BLT1G (onsemi)

This substitute provides direct electrical equivalence to the main part. It maintains the same 225 mW power rating, 80 Ohm impedance, and 39 V nominal voltage. The part is in active production status with 3400 units in stock, ensuring long-term availability. Operating temperature range extends to -65°C, providing enhanced low-temperature performance. RoHS3 compliance and MSL 1 rating match the original specification. This part is the preferred substitute for applications requiring identical power handling and impedance characteristics.

CMPZ5259B BK PBFREE (Central Semiconductor Corp)

This substitute offers increased power dissipation at 350 mW, providing design margin for thermal performance. Impedance remains at 80 Ohms, matching the original specification. The part is in active production with 1029 units in stock. Operating temperature range extends to -65°C. RoHS3 compliance and MSL 1 rating are maintained. This part is suitable for applications where higher power dissipation capability is beneficial or where tolerance relaxation to ±5% is acceptable.

CZRT55C39-G (Comchip Technology)

This substitute provides 350 mW power dissipation and extended operating temperature range to -65°C. Impedance is specified at 130 Ohms, which is higher than the original 80 Ohms specification. The part is in active production with 1010 units in stock. RoHS3 compliance and MSL 1 rating are maintained. This part is suitable for applications where impedance tolerance is not circuit-critical and higher power dissipation is desired.

All three substitute parts maintain RoHS3 compliance, MSL 1 rating, and the SOT-23-3 package format. Selection between substitutes depends on specific circuit requirements for power dissipation, impedance, and tolerance specifications.

Frequently Asked Questions (FAQ)

Q: Can MMBZ5259BLT1G directly replace MMBZ5259C-E3-18 without circuit modification?

A: Yes. MMBZ5259BLT1G maintains identical electrical specifications for voltage (39 V), power (225 mW), impedance (80 Ohms), and reverse leakage current (100 nA @ 30 V). The package format (SOT-23-3) is identical. The tolerance specification changes from ±2% to ±5%, which does not affect nominal voltage performance. The part is pin-compatible and requires no circuit modification.

Q: What is the difference between the three substitute parts?

A: MMBZ5259BLT1G matches the original power rating (225 mW) and impedance (80 Ohms). CMPZ5259B BK PBFREE and CZRT55C39-G both offer increased power dissipation (350 mW). CZRT55C39-G has higher impedance (130 Ohms) compared to the original 80 Ohms specification. All three maintain the 39 V nominal voltage and SOT-23-3 package.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All three substitute parts—MMBZ5259BLT1G, CMPZ5259B BK PBFREE, and CZRT55C39-G—are RoHS3 compliant with MSL 1 (Unlimited) moisture sensitivity level, matching the original part specification.

Q: Does the ±5% tolerance of substitute parts affect circuit performance?

A: The tolerance specification affects the acceptable voltage range around the 39 V nominal value. For applications where the ±2% tolerance of the original part is circuit-critical, MMBZ5259BLT1G maintains this tighter tolerance specification. For applications where ±5% tolerance is acceptable, all three substitutes are suitable.

Q: What is the operating temperature range difference?

A: The original MMBZ5259C-E3-18 operates from -55°C to 150°C. All three substitute parts extend the lower temperature limit to -65°C, providing enhanced performance in cold environments. The upper temperature limit remains 150°C for all parts.

Q: Can CZRT55C39-G be used if impedance is a critical parameter?

A: CZRT55C39-G specifies 130 Ohms maximum impedance, compared to 80 Ohms for the original part and the other two substitutes. If circuit design depends on the 80 Ohm impedance specification, CZRT55C39-G is not suitable. Use MMBZ5259BLT1G or CMPZ5259B BK PBFREE instead.

Q: Which substitute has the best availability?

A: MMBZ5259BLT1G (onsemi) has the highest inventory at 3400 units in stock, followed by CMPZ5259B BK PBFREE (1029 units) and CZRT55C39-G (1010 units). All three are in active production status.

Q: Are all substitute parts available in the same package format?

A: Yes. All substitute parts use the SOT-23-3 package format (also designated TO-236-3 or SC-59), which is identical to the original MMBZ5259C-E3-18 package. No PCB layout modification is required.

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