CZRT55C4V3-G Zener Diode 4.3V 350mW SOT-23-3 Equivalent & Substitute Parts

Part Overview

The CZRT55C4V3-G is a surface mount Zener diode manufactured by Comchip Technology, rated at 4.3 V nominal Zener voltage with 350 mW maximum power dissipation in a SOT-23-3 package. This component is classified as Active product status with full RoHS3 compliance and unlimited moisture sensitivity level (MSL 1). Substitute parts are identified based on matching electrical specifications and mechanical compatibility within the SOT-23-3 package family, enabling direct board-level replacement when component availability or supply chain requirements necessitate alternative sourcing.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	4.3	V
Tolerance	±7%	-
Power - Max	350	mW
Impedance (Max)	90	Ohms
Current - Reverse Leakage @ Vr	3	µA @ 1 V
Voltage - Forward (Vf) (Max) @ If	900	mV @ 10 mA
Operating Temperature Range	-65 to 150	°C
Package / Case	SOT-23-3	-
Mounting Type	Surface Mount	-
RoHS Status	ROHS3 Compliant	-

Substitute Part Grouping Explanation

Substitution eligibility for the CZRT55C4V3-G is determined by the following critical parameters:

Primary Matching Criteria:

Zener voltage (Nom): 4.3 V (exact match required)
Package / Case: SOT-23-3 (mechanical and thermal compatibility)
Mounting Type: Surface Mount (board assembly compatibility)
Operating Temperature Range: -65°C to 150°C minimum (thermal envelope)

Secondary Compatibility Parameters:

Power - Max: 350 mW or greater (thermal capability)
Impedance (Max): 90 Ohms or less (circuit performance)
Current - Reverse Leakage @ Vr: 3 µA @ 1 V or less (leakage characteristics)
Voltage - Forward (Vf) (Max) @ If: 900 mV @ 10 mA or less (forward conduction)

Tolerance Consideration: Zener voltage tolerance of ±7% or tighter is acceptable. Tighter tolerances (±2%, ±5%) provide improved circuit precision but remain functionally compatible with ±7% designs.

Compliance Requirements: All substitute parts must maintain RoHS3 compliance and REACH unaffected status for regulatory continuity.

Parameter Comparison

Manufacturer Part Number	Manufacturer	Vz (Nom)	Tolerance	Power (Max)	Zzt (Max)	Ir @ Vr	Vf (Max)	Temp Range	Package	RoHS Status	Product Status
CZRT55C4V3-G	Comchip Technology	4.3 V	±7%	350 mW	90 Ω	3 µA @ 1 V	900 mV @ 10 mA	-65 to 150°C	SOT-23-3	ROHS3	Active
BZX84B4V3-7-F	Diodes Incorporated	4.3 V	±2%	300 mW	90 Ω	3 µA @ 1 V	900 mV @ 10 mA	-65 to 150°C	SOT-23-3	ROHS3	Active
BZX84B4V3Q-7-F	Diodes Incorporated	4.3 V	±2%	300 mW	90 Ω	3 µA @ 1 V	900 mV @ 10 mA	-65 to 150°C	SOT-23-3	ROHS3	Active
BZX84C4V3-7-F	Diodes Incorporated	4.3 V	±7%	300 mW	90 Ω	3 µA @ 1 V	900 mV @ 10 mA	-65 to 150°C	SOT-23-3	ROHS3	Active
BZX84C4V3-TP	Micro Commercial Co	4.3 V	±5%	350 mW	90 Ω	3 µA @ 1 V	900 mV @ 10 mA	-55 to 150°C	SOT-23-3	ROHS3	Active
MMBZ5229B-7-F	Diodes Incorporated	4.3 V	±5%	350 mW	22 Ω	5 µA @ 1 V	900 mV @ 10 mA	-65 to 150°C	SOT-23-3	ROHS3	Active
BZX84C4V3 TR PBFREE	Central Semiconductor Corp	4.3 V	±5%	350 mW	90 Ω	3 µA @ 1 V	900 mV @ 10 mA	-65 to 150°C	SOT-23-3	ROHS3	Active

Engineering Selection Recommendations

Full Electrical and Thermal Equivalents (Direct Replacement):

BZX84C4V3 TR PBFREE (Central Semiconductor Corp) and BZX84C4V3-TP (Micro Commercial Co) provide complete parameter matching with the CZRT55C4V3-G, including identical 350 mW power rating, 90 Ohm impedance, and -65°C to 150°C operating range. Both maintain ROHS3 compliance and Active product status. BZX84C4V3 TR PBFREE offers the highest inventory availability (36,321 pcs) and is recommended for high-volume applications.

Reduced Power Rating Substitutes (300 mW):

BZX84B4V3-7-F, BZX84B4V3Q-7-F, and BZX84C4V3-7-F from Diodes Incorporated operate at 300 mW maximum power, representing a 14% reduction from the 350 mW specification. These parts maintain identical Zener voltage, impedance, and operating temperature range. BZX84B4V3Q-7-F includes AEC-Q101 automotive qualification and is suitable for applications where thermal margin is not critical. BZX84C4V3-7-F offers the largest inventory (6,100 pcs) among this group.

Alternative Impedance Characteristic:

MMBZ5229B-7-F (Diodes Incorporated) features a significantly lower impedance of 22 Ohms compared to the 90 Ohm specification, with slightly elevated reverse leakage (5 µA @ 1 V versus 3 µA @ 1 V). This part maintains 350 mW power rating and full temperature range compatibility. The lower impedance may affect circuit performance in applications sensitive to dynamic impedance characteristics.

Temperature Range Limitation:

BZX84C4V3-TP (Micro Commercial Co) operates over -55°C to 150°C, which is 10°C narrower at the lower temperature extreme compared to the -65°C to 150°C specification of the CZRT55C4V3-G. This part is suitable only for applications not requiring operation below -55°C.

Discontinued Status:

MMBZ5229B-7 (Diodes Incorporated) is discontinued at DiGi Electronics and should not be selected for new designs or long-term supply requirements.

Frequently Asked Questions (FAQ)

Q: Can BZX84B4V3-7-F replace CZRT55C4V3-G in all applications?

A: BZX84B4V3-7-F is electrically compatible with identical Zener voltage (4.3 V), impedance (90 Ω), and operating temperature range (-65°C to 150°C). However, the 300 mW power rating is 50 mW lower than the 350 mW specification. Substitution is valid only if circuit thermal analysis confirms that power dissipation remains below 300 mW under all operating conditions.

Q: What is the difference between BZX84B4V3-7-F and BZX84B4V3Q-7-F?

A: Both parts share identical electrical specifications (4.3 V, ±2% tolerance, 300 mW, 90 Ω impedance). BZX84B4V3Q-7-F includes AEC-Q101 automotive qualification and is packaged in Tape & Reel format, while BZX84B4V3-7-F is supplied in Cut Tape & Digi-Reel format. Selection depends on packaging requirements and automotive compliance needs.

Q: Why does MMBZ5229B-7-F have lower impedance (22 Ω) than other substitutes?

A: MMBZ5229B-7-F is a different Zener diode series with inherently lower dynamic impedance characteristics. While the 4.3 V Zener voltage and 350 mW power rating match the CZRT55C4V3-G, the 22 Ohm impedance may alter circuit performance in applications sensitive to Zener impedance. Circuit simulation or testing is necessary to confirm compatibility in impedance-critical designs.

Q: Is BZX84C4V3-TP suitable for applications requiring -65°C operation?

A: No. BZX84C4V3-TP operates over -55°C to 150°C, which does not meet the -65°C lower temperature limit of the CZRT55C4V3-G. This part is suitable only for applications with minimum operating temperature of -55°C or higher.

Q: What is the inventory advantage of BZX84C4V3 TR PBFREE?

A: BZX84C4V3 TR PBFREE maintains the highest available inventory at 36,321 pcs, compared to 1,011 pcs for the CZRT55C4V3-G. This part provides complete electrical equivalence (4.3 V, ±5% tolerance, 350 mW, 90 Ω impedance, -65°C to 150°C) and is recommended for high-volume production or long-term supply security.

Q: Are all substitute parts RoHS3 compliant?

A: All recommended substitute parts except MMBZ5229B-7 (discontinued) maintain ROHS3 compliance. MMBZ5229B-7 is RoHS non-compliant and should not be used in new designs. All active substitutes also maintain REACH unaffected status.

Q: Can tolerance differences affect circuit performance?

A: Zener voltage tolerance affects the precision of voltage regulation. The CZRT55C4V3-G specifies ±7% tolerance. Substitutes with tighter tolerances (±2% or ±5%) provide improved voltage accuracy but remain functionally compatible. Applications requiring specific voltage precision should confirm that the substitute tolerance meets circuit requirements.

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