KA33VBU Zener Diode Equivalent & Substitute Parts

Part Overview

The KA33VBU is a 33 V, 200 mW Zener diode manufactured by onsemi in a TO-92-2 through-hole package. This component is classified as obsolete, necessitating identification of active equivalent and substitute parts for ongoing design requirements and procurement needs. The part functions as a voltage reference and protection element in electronic circuits requiring 33 V regulation or transient suppression.

Substiute Parts

KA33VBU

onsemiIn Stock: 2533KA33VBU Datasheet

Current PartRFQ

2EZ33D5-TP

Micro Commercial CoIn Stock: 58092EZ33D5-TP Datasheet

SimilarRFQ

KA33VTA

Fairchild SemiconductorIn Stock: 4290KA33VTA Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the KA33VBU is determined by the following critical parameters:

Electrical Parameters:

• Zener voltage: 33 V nominal
• Voltage tolerance: ±6% or tighter
• Maximum power dissipation: 200 mW or greater
• Maximum impedance: 25 Ohms or lower

Mechanical Parameters:

• Mounting type: Through Hole
• Package compatibility: TO-92-2 or equivalent axial/radial through-hole packages

Environmental & Compliance:

• Operating temperature range: -20°C to 75°C minimum
• Moisture sensitivity: MSL 1 or MSL 3 acceptable for unlimited or 168-hour storage

Substitute parts are grouped into two categories:

Category 1 - Parametric Equivalent (Direct Replacement): Parts matching all electrical specifications and operating temperature range within the same package family.

Category 2 - Functional Equivalent (Higher Performance): Parts exceeding power dissipation or impedance specifications while maintaining 33 V zener voltage and through-hole mounting, suitable for applications with higher thermal or current demands.

Parameter Comparison

Engineering Selection Recommendations

KA33VTA (Parametric Equivalent - Recommended Primary Substitute)

The KA33VTA is an active product manufactured by Fairchild Semiconductor with identical electrical specifications to the KA33VBU: 33 V nominal zener voltage, ±6% tolerance, 200 mW maximum power, and 25 Ohms maximum impedance. Operating temperature range matches the original part (-20°C to 75°C). The TO-92-2 package provides direct mechanical compatibility. ROHS3 compliance and MSL 3 rating support modern manufacturing and storage requirements. This part is the preferred direct replacement for applications requiring equivalent performance characteristics.

2EZ33D5-TP (Functional Equivalent - Higher Power Applications)

The 2EZ33D5-TP is an active product manufactured by Micro Commercial Co suitable for applications requiring higher power dissipation. This part maintains the 33 V zener voltage specification with improved ±5% tolerance and provides 2 W maximum power dissipation (10× the original part). The DO-41 axial package differs mechanically from the TO-92-2 but accommodates through-hole mounting. Extended operating temperature range (-55°C to 150°C) and lower impedance (23 Ohms) provide enhanced performance margins. ROHS3 compliance and MSL 1 rating are supported. Selection of this part is appropriate for designs with higher thermal loads or where extended temperature operation is required, provided PCB layout accommodates the DO-41 package footprint.

Frequently Asked Questions (FAQ)

Q: Can the KA33VTA directly replace the KA33VBU without circuit modification?

A: Yes. The KA33VTA provides identical electrical parameters (33 V, ±6%, 200 mW, 25 Ohms impedance) and operates within the same temperature range (-20°C to 75°C). The TO-92-2 package is mechanically compatible. No circuit design changes are required.

Q: What is the primary difference between the KA33VTA and 2EZ33D5-TP?

A: The KA33VTA is a parametric equivalent with 200 mW power rating in TO-92-2 package. The 2EZ33D5-TP is a functional equivalent with 2 W power rating in DO-41 package. Selection depends on power dissipation requirements and available PCB space for the different package footprint.

Q: Can the 2EZ33D5-TP be used in a circuit designed for the KA33VBU?

A: The 2EZ33D5-TP maintains the 33 V zener voltage and is electrically compatible. However, the DO-41 axial package differs from the TO-92-2 radial package. PCB layout modification is required to accommodate the different lead configuration and spacing. Electrical performance is enhanced (lower impedance, higher power rating).

Q: What does the ±6% tolerance specification mean for the KA33VBU and KA33VTA?

A: The zener voltage will be within ±6% of the 33 V nominal value across the specified operating temperature range and load conditions. This means the actual zener voltage will fall between 31.02 V and 34.98 V. The 2EZ33D5-TP offers tighter ±5% tolerance (31.35 V to 34.65 V).

Q: Are there temperature range considerations when substituting these parts?

A: The KA33VBU and KA33VTA operate identically from -20°C to 75°C. The 2EZ33D5-TP extends this range to -55°C to 150°C. If the application operates within -20°C to 75°C, all three parts are suitable. For extended temperature applications, the 2EZ33D5-TP provides additional margin.

Q: What is the significance of the MSL (Moisture Sensitivity Level) rating?

A: MSL 1 (KA33VBU, 2EZ33D5-TP) indicates unlimited shelf life without moisture control. MSL 3 (KA33VTA) requires controlled storage conditions (168 hours maximum at specified humidity before reflow soldering). For standard manufacturing environments with proper storage, both ratings are acceptable.

Q: Does the impedance specification affect circuit performance?

A: Maximum impedance (25 Ohms for KA33VBU and KA33VTA; 23 Ohms for 2EZ33D5-TP) determines the dynamic resistance of the zener diode. Lower impedance provides better voltage regulation under varying load conditions. The 2EZ33D5-TP offers marginally superior regulation characteristics.

Q: Why is the KA33VBU listed as obsolete?

A: Obsolete status indicates the part is no longer manufactured by onsemi. Active equivalent parts (KA33VTA, 2EZ33D5-TP) are available from alternative manufacturers and should be used for new designs and ongoing procurement.