BZX84C33 Equivalent & Substitute Parts

Part Overview

The BZX84C33 is a 33 V Zener diode manufactured by onsemi, rated for 350 mW power dissipation in a surface mount SOT-23-3 package. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement. The BZX84C33 operates across a temperature range of -55°C to 150°C with ±6% voltage tolerance and is suitable for voltage regulation and protection applications in electronic circuits.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nominal)	33	V
Tolerance	±6%	—
Power - Maximum	350	mW
Impedance (Maximum)	80	Ohms
Current - Reverse Leakage @ Vr	50	nA @ 23.1 V
Voltage - Forward (Maximum) @ If	900	mV @ 10 mA
Operating Temperature Range	-55 to 150	°C
Mounting Type	Surface Mount	—
Package / Case	TO-236-3, SC-59, SOT-23-3	—
Moisture Sensitivity Level	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the BZX84C33 is determined by the following critical parameters:

Primary Substitution Criteria:

Zener voltage: 33 V nominal
Package type: SOT-23-3 (TO-236-3, SC-59)
Mounting type: Surface Mount
Impedance: 80 Ohms maximum
Reverse leakage current: 50 nA @ 23.1 V
Forward voltage: 900 mV @ 10 mA maximum

Secondary Considerations:

Power rating: 350 mW or higher
Voltage tolerance: ±6% or tighter
Operating temperature range: -55°C to 150°C minimum
Moisture sensitivity: MSL 1 (Unlimited)

Substitute parts are grouped into three categories based on product status and compliance:

Active onsemi variants (BZX84C33LT1G, BZX84C33LT3G): Direct replacements with identical electrical specifications and improved temperature range (-65°C to 150°C). Lower power rating (225 mW) requires application verification.
Automotive-grade alternatives (SZBZX84C33LT1G, SZBZX84C33LT3G): AEC-Q101 qualified variants with identical electrical parameters, suitable for automotive applications.
Cross-manufacturer equivalents (NXP/Nexperia BZX84-C33,215 and BZX84-C33,235, Diodes Incorporated BZX84C33-7-F, Micro Commercial Co BZX84B33-TP, Panjit BZX84C33_R1_00001, Central Semiconductor CMPZ5257B): Parts meeting core electrical specifications with variations in power rating, tolerance, and leakage current.

Parameter Comparison

Part Number	Manufacturer	Vz (V)	Tolerance	Power (mW)	Zzt (Ohms)	Ir @ Vr (nA)	Vf @ If (mV)	Temp Range (°C)	Status	RoHS
BZX84C33	onsemi	33	±6%	350	80	50 @ 23.1	900 @ 10	-55 to 150	Obsolete	—
BZX84C33LT1G	onsemi	33	±6%	225	80	50 @ 23.1	900 @ 10	-65 to 150	Active	ROHS3
BZX84C33LT3G	onsemi	33	±6%	225	80	50 @ 23.1	900 @ 10	-65 to 150	Active	ROHS3
SZBZX84C33LT1G	onsemi	33	±6%	225	80	50 @ 23.1	900 @ 10	-65 to 150	Active	ROHS3
SZBZX84C33LT3G	onsemi	33	±6%	225	80	50 @ 23.1	900 @ 10	-65 to 150	Active	ROHS3
BZX84-C33,215	NXP Semiconductors	33	±5%	250	80	50 @ 23.1	900 @ 10	-65 to 150	Active	—
BZX84-C33,235	Nexperia USA Inc.	33	±5%	250	80	50 @ 23.1	900 @ 10	-65 to 150	Active	ROHS3
BZX84B33-TP	Micro Commercial Co	33	±2%	350	80	100 @ 23.1	900 @ 10	-55 to 150	Active	—
BZX84C33-7-F	Diodes Incorporated	33	±6%	300	80	100 @ 23.1	900 @ 10	-65 to 150	Active	ROHS3
BZX84C33_R1_00001	Panjit International Inc.	33	±5%	410	80	100 @ 23.1	—	-55 to 150	Active	ROHS3
CMPZ5257B BK PBFREE	Central Semiconductor Corp	33	±5%	350	58	100 @ 25	900 @ 10	-65 to 150	Active	ROHS3

Engineering Selection Recommendations

For Direct Replacement (Obsolete Part Mitigation):

The BZX84C33LT1G and BZX84C33LT3G from onsemi provide the most direct functional equivalence. Both are active products with identical electrical specifications to the obsolete BZX84C33, with the exception of reduced power rating (225 mW versus 350 mW). These parts are ROHS3 compliant and extend the operating temperature range to -65°C. Selection between LT1G (Cut Tape & Digi-Reel) and LT3G (Tape & Reel) depends on packaging requirements.

For Automotive Applications:

SZBZX84C33LT1G and SZBZX84C33LT3G are AEC-Q101 qualified automotive-grade variants with identical electrical performance to the onsemi LT1G/LT3G series. These are suitable for automotive circuit protection and voltage regulation applications.

For Higher Power Dissipation:

BZX84C33_R1_00001 (Panjit) offers 410 mW power rating, the highest among available substitutes, with ±5% tolerance and ROHS3 compliance. BZX84B33-TP (Micro Commercial Co) provides 350 mW matching the original part, with tighter ±2% tolerance but higher reverse leakage (100 nA).

For Cross-Manufacturer Sourcing:

BZX84-C33,215 and BZX84-C33,235 (NXP/Nexperia) are active products with 250 mW power rating and ±5% tolerance. BZX84C33-7-F (Diodes Incorporated) offers 300 mW with ±6% tolerance and extended temperature range (-65°C to 150°C).

Compliance Considerations:

All recommended substitutes maintain SOT-23-3 package compatibility, 80 Ohms impedance, and MSL 1 moisture sensitivity. ROHS3 compliance is available across most active alternatives. Reverse leakage current increases from 50 nA to 100 nA in several alternatives; circuit design must accommodate this parameter variation.

Frequently Asked Questions (FAQ)

Q: Can BZX84C33LT1G directly replace the obsolete BZX84C33?

A: BZX84C33LT1G is electrically equivalent with identical Zener voltage (33 V), tolerance (±6%), impedance (80 Ohms), and forward voltage characteristics. The primary difference is reduced power rating (225 mW versus 350 mW). Direct replacement is valid if circuit power dissipation does not exceed 225 mW. Extended temperature range (-65°C to 150°C) provides additional margin.

Q: What is the difference between BZX84C33LT1G and BZX84C33LT3G?

A: Both parts are electrically identical. The difference is packaging: LT1G is supplied in Cut Tape & Digi-Reel format, while LT3G is supplied in Tape & Reel format. Selection depends on assembly line requirements and tape reel compatibility.

Q: Are automotive-grade SZBZX84C33 variants suitable for non-automotive applications?

A: Yes. SZBZX84C33LT1G and SZBZX84C33LT3G are AEC-Q101 qualified but functionally equivalent to standard onsemi variants. They can be used in any application requiring 33 V Zener diodes with identical electrical specifications.

Q: Why do some substitutes have higher reverse leakage current (100 nA versus 50 nA)?

A: Reverse leakage current is a manufacturing parameter that varies by manufacturer and process. Parts with 100 nA leakage remain within acceptable limits for most voltage regulation and protection circuits. Circuit design must verify that increased leakage does not affect performance in high-impedance applications.

Q: Can I use BZX84C33_R1_00001 if my circuit requires 350 mW dissipation?

A: Yes. BZX84C33_R1_00001 (Panjit) is rated for 410 mW, exceeding the original 350 mW specification. It maintains 33 V Zener voltage, 80 Ohms impedance, and ±5% tolerance. This part provides additional thermal margin for power-constrained applications.

Q: What is the impact of ±5% tolerance versus ±6% tolerance?

A: Tighter tolerance (±5%) provides more precise Zener voltage control. Parts with ±5% tolerance (BZX84-C33,215, BZX84-C33,235, BZX84C33_R1_00001, CMPZ5257B) are suitable for applications requiring stricter voltage regulation. The ±6% tolerance of the original BZX84C33 and onsemi LT1G/LT3G variants is acceptable for standard protection and regulation circuits.

Q: Are all substitutes compatible with the SOT-23-3 package footprint?

A: Yes. All listed substitutes use TO-236-3, SC-59, or SOT-23-3 package designations, which are mechanically and electrically equivalent. PCB footprints are interchangeable.

Q: Which substitute offers the best compliance profile?

A: BZX84C33LT1G, BZX84C33LT3G, SZBZX84C33LT1G, and SZBZX84C33LT3G are ROHS3 compliant onsemi products with active status. For cross-manufacturer options, BZX84-C33,235 (Nexperia) and BZX84C33-7-F (Diodes Incorporated) are ROHS3 compliant with active product status.

Q: What is the temperature range difference between the original BZX84C33 and active substitutes?

A: The original BZX84C33 operates -55°C to 150°C. Most active substitutes extend the lower limit to -65°C, providing 10°C additional margin at low temperatures. This is beneficial for applications in cold environments or with wide operating temperature requirements.

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