DC to DC SSR Solid State Relays

In a DC to DC Solid-State Relay(DC SSR), various semiconductor technologies are used for switching the DC load. The main technologies typically used in DC SSRs are MOSFETs, IGBTs (Insulated Gate Bipolar Transistors), and Bipolar Junction Transistors (BJTs). Each of these technologies has its own strengths and trade-offs, and they are suited for different applications depending on factors like voltage, current handling, switching speed, and efficiency.

 

Differently to an AC SSR which has a latching function, current continues to flow in the drive circuit of a DC SSR, holding it on until the input signal is removed. The output current capability is continuously proportional to the input drive current through the photocoupler. The on-state voltage is similar to that of an AC SSR, which gives rise to most of the package dissipation; for this reason, Heat Sinking requirements are also similar.

 

Kane electric offers a complete range of DC solid state relays up to 600Vdc, 0 to 200A.

 

Let’s dive into each technology:

 

MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) DC to DC Solid State Relays

MOSFETs are commonly used when speed and energy efficiency are important. They respond quickly and don’t waste much energy when conducting electricity. Because they work best at lower voltages and higher currents, they’re often found in devices like power supplies, battery systems, microcontroller circuits, cars, and solar panels.

 

How it works:

A DC Solid-State Relay (DC SSR) using MOSFET technology works by using one or more MOSFET transistors to switch DC current on or off electronically, without any moving parts.

 

MOSFETs are a type of field-effect transistor (FET) used for switching DC current. In MOSFETs, the current is controlled by the voltage applied to the gate terminal, which is insulated from the rest of the device by a thin layer of oxide. When a sufficient voltage is applied to the gate, the MOSFET conducts and allows current to flow between the drain and the source.

 

Key features:

• High efficiency: MOSFETs have low on-resistance, which results in low conduction losses, making them highly efficient for switching DC circuits.
• Fast switching: MOSFETs can switch on and off very quickly, making them suitable for high-speed applications.
• Low gate drive requirement: They require very little current to control the gate, which reduces the complexity of the control circuit.
• Good for low-voltage, high-current applications: MOSFETs are ideal for low-voltage, high-current circuits where switching efficiency and speed are critical.

 

Applications:

• Low-to-medium power DC SSRs.
• Power supplies, battery management systems.
• Microcontroller interfacing (for switching small to medium DC loads).
• Automotive and solar power systems.

DC Mosfet Solid State Relays are ideal for applications requiring transient overcurrent withstand (motors).