SMAJ33CA
400W peak pulse power bidirectional TVS diode with 33V working voltage and 53.3V clamping voltage. Ideal for 24V system protection in automotive and industrial applications.
Product Overview
Description
The Littelfuse SMAJ33CA is a high-performance bidirectional transient voltage suppression (TVS) diode designed to protect sensitive electronics from voltage transients and ESD events. With a 400W peak pulse power rating and fast response time, this device provides reliable protection for automotive, industrial, and consumer electronics applications.
Featuring a 33V working voltage and 53.3V maximum clamping voltage, the SMAJ33CA is ideal for protecting 24V systems against load dump, inductive kickback, and other transient events. The bidirectional configuration provides protection for both positive and negative voltage transients, simplifying circuit design.
Packaged in a compact SMA (DO-214AC) surface-mount package, the SMAJ33CA offers excellent thermal performance and is compatible with automated assembly processes. The device meets AEC-Q101 automotive qualification requirements, ensuring reliable operation in harsh automotive environments.
Product Series
SMAJ Series
Primary Application
24V automotive system protection
Key Features
- 400W peak pulse power rating (10/1000µs)
- Bidirectional protection
- Fast response time < 1 picosecond
- Excellent clamping capability
- AEC-Q101 automotive qualified
- Surface-mount SMA package
- Low leakage current < 1µA
- RoHS compliant
Specifications
| workingVoltage | 33V |
|---|---|
| breakdownVoltage | 36.7V - 40.6V |
| clampingVoltage | 53.3V |
| peakPulsePower | 400W |
| peakPulseCurrent | 7.5A |
| leakageCurrent | 1µA |
| responseTime | < 1ps |
| package | SMA (DO-214AC) |
| qualification | AEC-Q101 |
Applications
24V automotive system protection
Automotive and EV electronics
Industrial control systems
Industrial automation and control
Power supply protection
Power conversion and supply
Telecommunications equipment
Communication and interface
Consumer electronics
Consumer electronics
LED lighting systems
Electronic system design
FAE Expert Insights
"The SMAJ33CA is one of my most recommended TVS diodes for 24V system protection. In my 15 years of supporting industrial and automotive designs, I've seen this device provide reliable protection in thousands of applications. The 33V working voltage provides good margin for 24V systems while the 53V clamping voltage protects sensitive electronics. One key advantage is the AEC-Q101 qualification - this is essential for automotive applications where reliability is critical. I typically recommend placing the TVS as close as possible to the connector or the component being protected, with minimal trace length to reduce parasitic inductance. For high-energy transients, consider using multiple TVS devices in parallel or stepping up to the SMBJ series (600W). The bidirectional configuration simplifies design by protecting against both positive and negative transients with a single device."
Reliable 24V system protection with AEC-Q101 qualification for automotive applications
— David Wang, BeiLuo
Frequently Asked Questions
Where should I place the TVS diode in my circuit?
Proper placement of TVS diodes is critical for effective protection: (1) Place as close as possible to the point of entry for transients - typically at connectors or input terminals; (2) Minimize trace length between TVS and protected circuit - keep under 5mm if possible; (3) Use wide, short traces to minimize parasitic inductance; (4) Place on the same layer as the protected component when possible; (5) For power lines, place TVS across the power and ground rails; (6) For signal lines, place TVS between signal and ground; (7) Consider using multiple TVS devices at different points for distributed protection. The goal is to clamp the transient before it reaches sensitive components. Parasitic inductance in the protection path can cause voltage overshoot during fast transients, reducing protection effectiveness. For high-frequency applications, consider using TVS arrays with integrated low-capacitance diodes.
Place TVS as close as possible to the transient entry point with minimal trace length. Use wide traces and consider parasitic inductance in the protection path.
What is the difference between unidirectional and bidirectional TVS diodes?
TVS diodes come in two configurations: (1) Unidirectional - Acts like a Zener diode in reverse bias, clamping positive transients. In forward bias, it conducts like a standard diode. Used when only positive voltage transients need protection or when combined with a series diode for bidirectional protection; (2) Bidirectional - Contains two TVS elements in series back-to-back, providing clamping for both positive and negative transients. Functions like two Zener diodes in series. Used when protection is needed for both polarities, common in AC circuits or bipolar signal lines. For DC circuits with positive voltage only, unidirectional TVS is typically sufficient and slightly more efficient. For circuits that may see negative transients or for bipolar signals, bidirectional TVS simplifies design by providing protection with a single component. The SMAJ33CA is bidirectional, making it suitable for applications where transient polarity is unknown or varies.
Use unidirectional for DC circuits with positive voltage only. Use bidirectional for AC circuits, bipolar signals, or when transient polarity is unknown.