SMAJ36CA 36V TVS Diode: Providing Reliable Surge and Transient Protection for 24V DC Power Supplies

Introduction

In industrial control equipment, 24V DC is one of the most common power supply voltages. However, in actual operation, power lines are not always stable. Switching actions, inductive loads, and external surges can all cause transient overvoltages, impacting downstream electronic components.

Therefore, adding appropriate TVS protection at the 24V DC power input is a common protection method in industrial equipment. The Semiware SMAJ36CA TVS diode is designed for these applications. In elevator call board circuit protection schemes, the SMAJ36CA TVS is used at the DC 24V power supply terminal to provide transient overvoltage protection for downstream circuits.

I. SMAJ36CA Main Parameters and Characteristics

The SMAJ36CA is a 36V TVS diode in an SMA surface mount package. It features high peak pulse power and fast response capability, making it suitable for power inputs, industrial control, and other locations susceptible to transient interference.

1.1 SMAJ36CA main parameters

1.2 Why is the SMAJ36CA suitable for 24V DC power supply protection?

For 24V DC systems, the operating voltage of a TVS (Transient Voltage Suppressor) needs to be balanced between the normal supply voltage and the protection action voltage.

• The SMAJ36CA has a maximum reverse operating voltage of 36V. Under normal 24V supply conditions, it maintains high impedance and will not significantly affect the normal operation of the circuit.
• When a large transient overvoltage occurs on the power line and reaches its breakdown region, the device quickly enters a low-impedance state, bypassing the excessive transient energy and reducing the voltage across subsequent circuits through clamping.
• Simultaneously, its 400W peak pulse power and 58.1V maximum clamping voltage enable the SMAJ36CA to meet the transient protection requirements of many 24V industrial power supply inputs.

Therefore, the SMAJ36CA is a practical TVS protection choice for 24V industrial controllers, elevator control boards, automation equipment, and other 24V power supply systems.

II. Application of SMAJ36CA in Elevator Call Boards

During operation, elevator systems involve motors, relays, controllers, and long power and signal lines. These circuits are susceptible to switching actions and external electrical interference. Therefore, in addition to ensuring normal power supply, transient protection for the power supply and communication interfaces is crucial.

Elevator call board systems include functional modules such as DC24V, audio, display, CAN, buttons, and RS485. The SMAJ36CA series is used for DC24V power supply protection.

TVS is typically installed at the DC24V input, close to the power inlet.

When a transient overvoltage occurs on the power line, the TVS quickly enters the conducting state, bypassing the transient energy and limiting the voltage within a certain range. This reduces the impact of high-voltage spikes on downstream power management devices, MCUs, and other sensitive components.

It is recommended to place the SMAJ36CA near the DC24V power inlet to suppress transient voltages before they reach the subsequent circuitry. The shorter the PCB traces and the smaller the loop area, the better the actual protection effect of TVS.

III. Besides Elevator Call Boards, What Other Scenarios Can the SMAJ36CA Be Used In?

3.1 Industrial Control Equipment

• PLCs, industrial controllers, I/O modules, and other equipment typically use 24V DC power. The SMAJ36CA can be used for transient overvoltage protection at the power input.

3.2 Industrial Automation Equipment

• Automation equipment contains numerous relays, motors, and actuators. Switching actions can generate transient interference. The SMAJ36CA can be used at the DC power input to help reduce the impact of these transients on the control circuitry.

3.3 Sensors and Control Modules

• Many industrial sensors, controllers, and field devices use 24V power. The SMAJ36CA can be used for power supply protection, improving the reliability of equipment in the face of electrical transient interference.

3.4 Communication and Network Equipment

• Some industrial communication equipment uses 24V DC power. A suitable TVS can be selected for power supply protection based on the system's actual operating voltage and transient environment.

3.5 Power Management and Other DC Input Circuits

• For DC input circuits around 24V, the SMAJ36CA can also be used as a front-end transient protection device, working in conjunction with subsequent fuses, DC/DC converters, power management ICs, etc.

IV. Key Advantages of the Semiware SMAJ36CA TVS Diode

When selecting a TVS diode, performance parameters are important, but cost, lead time, and long-term supply capability must also be considered.

4.1 Performance Parameters Meet Industry Standards

• The Semiware SMAJ36CA's parameters are compatible with industry standards, making it a viable alternative to Littelfuse.

4.2 Standard SMA Package

• SMA is a mature surface mount package, suitable for automated mounting and mass production, and also facilitates PCB layout.

4.3 Original Manufacturer Supply, More Competitive Costs

• As the original manufacturer of TVS and other circuit protection devices, Semiware reduces intermediate supply links, helping to control procurement costs. For customers needing alternatives to similar devices from brands like Littelfuse and Vishay, Semiware can also provide corresponding alternative solutions based on specific parameters and application requirements.

4.5 Delivery Time and Supply Stability

• Semiware can provide bulk supply support according to customer project requirements.

4.6 More Than Just Single Devices, Protection Solutions Available

• Semiware's product range covers a variety of circuit protection products, including TVS, ESD protection devices, GDTs, varistors, and PPTCs.
• Therefore, in practical circuit applications, targeted protection devices can be selected based on different interfaces and power supply locations.

Conclusion

For 24V DC powered equipment, protecting the power input from transient overvoltages is a crucial component of improving overall system reliability.

From elevator call panels and industrial controllers to automation equipment and sensor modules, the SMAJ36CA provides a practical solution for suppressing transient voltages and reducing the risk of circuit damage.

As an original equipment manufacturer (OEM), Semiware offers a comprehensive range of circuit protection devices widely used in power, industrial, automotive, and consumer electronics sectors. For detailed electrical specifications, package information, or product selection support, please contact us.

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