CZRT55C22-G Zener Diode 22V 350mW SOT-23-3 Equivalent & Substitute Parts

Part Overview

The CZRT55C22-G is a surface mount Zener diode manufactured by Comchip Technology, rated at 22 V nominal Zener voltage with 350 mW maximum power dissipation in SOT-23-3 package. This component is classified as Active product status with full RoHS3 compliance and unlimited moisture sensitivity level (MSL 1). Zener diodes of this specification are used in voltage regulation, overvoltage protection, and reference circuits where precise voltage clamping at 22 V is required. Equivalent and substitute parts are identified based on matching electrical characteristics and mechanical compatibility to ensure direct circuit board replacement without design modification.

Key Parameters

Parameter	Value	Unit	Significance for Substitution
Voltage - Zener (Nom)	22	V	Primary electrical specification; must match exactly
Power - Max	350	mW	Thermal rating; substitutes must equal or exceed this value
Tolerance	±6%	%	Voltage accuracy; tighter tolerance acceptable
Impedance (Max)	55	Ohms	Dynamic impedance; affects circuit response
Current - Reverse Leakage @ Vr	100 nA @ 15.4 V	nA	Leakage specification; lower values acceptable
Voltage - Forward (Vf) (Max) @ If	900 mV @ 10 mA	mV	Forward conduction characteristic; must match
Operating Temperature	-65 to 150	°C	Thermal operating range; must match or exceed
Package / Case	TO-236-3, SC-59, SOT-23-3	-	Physical footprint; must be identical for PCB compatibility
Mounting Type	Surface Mount	-	Assembly method; must match
RoHS Status	ROHS3 Compliant	-	Regulatory compliance; must maintain

Substitute Part Grouping Explanation

Substitute parts for the CZRT55C22-G are classified into two categories based on electrical parameter alignment:

Category 1: Manufacturer Recommended Substitutes (MFR Recommended) These parts are explicitly recommended by manufacturers as direct replacements. They maintain the 22 V Zener voltage specification and SOT-23-3 package compatibility. Substitutes in this category include BZX84B22-7-F, BZX84B22Q-7-F, BZX84C22-7-F, DDZX22D-13, DDZX22D-7, and MMBZ5251B-7-F from Diodes Incorporated.

Category 2: Parametric Equivalents These parts meet the core electrical requirements (22 V Zener voltage, SOT-23-3 package, surface mount) but may originate from different manufacturers. BZX84C22 TR from Central Semiconductor Corp is classified as a parametric equivalent.

Substitution Logic: All substitute parts must satisfy the following mandatory criteria:

Zener voltage (Vz) = 22 V nominal
Package = SOT-23-3 (TO-236-3, SC-59)
Mounting type = Surface Mount
Operating temperature range = -65°C to 150°C minimum
RoHS3 compliance maintained
Power rating ≥ 300 mW (original specification 350 mW; lower power acceptable only if circuit design permits)
Forward voltage (Vf) @ 10 mA = 900 mV maximum
Reverse leakage ≤ 100 nA @ specified voltage

Tolerance variations (±2%, ±3%, ±5%, ±6%) are acceptable as they represent tighter or equivalent voltage accuracy. Impedance variations are acceptable within the range of 29–55 Ohms as this parameter affects transient response but does not prevent functional substitution in most applications.

Parameter Comparison

Part Number	Manufacturer	Vz (Nom)	Tolerance	Power (Max)	Impedance (Max)	Reverse Leakage @ Vr	Vf (Max) @ 10mA	Temp Range	Package	Inventory
CZRT55C22-G	Comchip Technology	22 V	±6%	350 mW	55 Ω	100 nA @ 15.4 V	900 mV	-65 to 150°C	SOT-23-3	953 Pcs
BZX84B22-7-F	Diodes Incorporated	22 V	±2%	300 mW	55 Ω	100 nA @ 15.4 V	900 mV	-65 to 150°C	SOT-23-3	875 Pcs
BZX84B22Q-7-F	Diodes Incorporated	22 V	±2%	300 mW	55 Ω	100 nA @ 15.4 V	900 mV	-65 to 150°C	SOT-23-3	975 Pcs
BZX84C22-7-F	Diodes Incorporated	22 V	±6%	300 mW	55 Ω	100 nA @ 15.4 V	900 mV	-65 to 150°C	SOT-23-3	35300 Pcs
DDZX22D-13	Diodes Incorporated	22 V	±3%	300 mW	30 Ω	50 nA @ 17 V	900 mV	-65 to 150°C	SOT-23-3	769 Pcs
DDZX22D-7	Diodes Incorporated	22 V	±3%	300 mW	30 Ω	50 nA @ 17 V	900 mV	-65 to 150°C	SOT-23-3	6050 Pcs
MMBZ5251B-7-F	Diodes Incorporated	22 V	±5%	350 mW	29 Ω	100 nA @ 17 V	900 mV	-65 to 150°C	SOT-23-3	4400 Pcs
BZX84C22 TR	Central Semiconductor Corp	22 V	±5%	350 mW	55 Ω	50 nA @ 15.4 V	900 mV	-65 to 150°C	SOT-23-3	1838 Pcs

Engineering Selection Recommendations

Primary Selection Criteria:

Electrical Compatibility: All listed substitute parts maintain the 22 V Zener voltage specification and are electrically compatible with circuits designed for CZRT55C22-G. Selection among substitutes depends on secondary parameters and availability.
Power Rating Consideration: The original part specifies 350 mW maximum power dissipation. Substitute parts rated at 300 mW (BZX84B22-7-F, BZX84B22Q-7-F, BZX84C22-7-F, DDZX22D-13, DDZX22D-7) are acceptable for applications where circuit design does not require the full 350 mW thermal margin. MMBZ5251B-7-F and BZX84C22 TR maintain the 350 mW rating and are preferred for thermally demanding applications.
Tolerance Selection: Tighter tolerance parts (±2%, ±3%, ±5%) provide improved voltage accuracy compared to the original ±6% specification. BZX84B22-7-F and BZX84B22Q-7-F offer ±2% tolerance for precision voltage reference applications. DDZX22D-13 and DDZX22D-7 provide ±3% tolerance with lower impedance (30 Ω vs. 55 Ω), beneficial for low-impedance circuit requirements.
Impedance Characteristics: Parts with lower impedance (DDZX22D series at 29–30 Ω, MMBZ5251B-7-F at 29 Ω) provide faster transient response and are suitable for high-frequency switching applications. Standard impedance parts (55 Ω) are suitable for general-purpose voltage regulation.
Regulatory and Compliance Status: All substitute parts maintain RoHS3 compliance, REACH unaffected status, and MSL 1 (unlimited) moisture sensitivity level, ensuring regulatory equivalence with the original part.
Automotive Grade Consideration: BZX84B22Q-7-F carries AEC-Q101 automotive qualification, making it the preferred choice for automotive and high-reliability applications requiring formal qualification documentation.
Availability and Lead Time: BZX84C22-7-F from Diodes Incorporated offers the highest inventory (35,300 Pcs), providing superior availability for high-volume production. DDZX22D-7 (6,050 Pcs) and MMBZ5251B-7-F (4,400 Pcs) provide secondary sourcing options.

Recommended Substitution Priority:

First Choice (Highest Compatibility): BZX84C22-7-F (matching tolerance ±6%, equivalent impedance 55 Ω, highest inventory)
Second Choice (Precision Applications): BZX84B22-7-F or BZX84B22Q-7-F (tighter ±2% tolerance, automotive qualified option available)
Third Choice (Low-Impedance Applications): DDZX22D-7 (lower impedance 30 Ω, ±3% tolerance, high inventory)
Fourth Choice (Full Power Rating): MMBZ5251B-7-F (maintains 350 mW rating, lower impedance 29 Ω)

Frequently Asked Questions (FAQ)

Q1: Can I substitute CZRT55C22-G with BZX84C22-7-F without circuit modification?

A: Yes. BZX84C22-7-F is electrically and mechanically compatible. Both parts specify 22 V Zener voltage, ±6% tolerance, 900 mV forward voltage at 10 mA, and identical SOT-23-3 package. The 50 mW reduction in power rating (300 mW vs. 350 mW) is acceptable unless the circuit design specifically requires the full thermal margin. Direct PCB replacement is possible without design changes.

Q2: What is the difference between BZX84B22-7-F and BZX84C22-7-F?

A: The primary difference is voltage tolerance: BZX84B22-7-F specifies ±2% tolerance versus BZX84C22-7-F at ±6%. Both maintain 22 V nominal Zener voltage, 300 mW power rating, and SOT-23-3 package. BZX84B22-7-F is preferred for precision voltage reference circuits where tighter voltage accuracy is required. BZX84C22-7-F is suitable for general-purpose voltage regulation where ±6% tolerance is acceptable.

Q3: Why do DDZX22D-13 and DDZX22D-7 have lower impedance (30 Ω) compared to other substitutes (55 Ω)?

A: Lower impedance indicates faster transient response and lower dynamic resistance during voltage regulation. DDZX22D series parts are optimized for applications requiring rapid voltage stabilization under load transients. The impedance difference does not affect DC voltage regulation but improves AC ripple rejection and transient suppression. Selection depends on circuit requirements for transient response speed.

Q4: Is BZX84B22Q-7-F suitable for automotive applications?

A: Yes. BZX84B22Q-7-F carries AEC-Q101 automotive qualification and is specifically designed for automotive-grade applications. It maintains all electrical specifications (22 V, ±2% tolerance, 300 mW, SOT-23-3) and is the recommended choice for automotive circuits, industrial equipment, and high-reliability applications requiring formal qualification documentation.

Q5: Can I use MMBZ5251B-7-F as a direct replacement for CZRT55C22-G?

A: Yes, with consideration of impedance differences. MMBZ5251B-7-F maintains 22 V Zener voltage, 350 mW power rating, and SOT-23-3 package. However, impedance is 29 Ω versus the original 55 Ω, resulting in faster transient response. This is generally beneficial but may affect circuit behavior in applications with specific impedance requirements. Verify circuit performance if transient response characteristics are critical.

Q6: What does "Tape & Reel (TR)" packaging mean, and does it affect substitution?

A: Tape & Reel packaging indicates the component is supplied on continuous carrier tape wound on a reel for automated assembly. This is a supply format, not a functional specification. Parts supplied in Tape & Reel format are identical to those in Cut Tape format; packaging format does not affect electrical performance or substitution compatibility. BZX84C22-7-F is available in Cut Tape & Digi-Reel format and is functionally equivalent to Tape & Reel versions.

Q7: Are all substitute parts RoHS3 compliant?

A: Yes. All listed substitute parts maintain RoHS3 compliance, REACH unaffected status, and MSL 1 (unlimited) moisture sensitivity level, ensuring regulatory equivalence with CZRT55C22-G. No additional compliance verification is required for substitution.

Q8: Which substitute part offers the best availability?

A: BZX84C22-7-F from Diodes Incorporated offers the highest inventory at 35,300 Pcs, providing superior availability for high-volume production and rapid delivery. DDZX22D-7 (6,050 Pcs) and MMBZ5251B-7-F (4,400 Pcs) provide secondary sourcing options with acceptable inventory levels.

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