Module protects from over-voltage damage

Claimed to be the industry’s first precision module for low power, low voltage voltage clamp, the SABMBOVP is available from Advanced Linear Devices (ALD). It protects low voltage designs from damage caused by over-voltage conditions in systems starting at 5V or less.

The SABMBOVP family voltage clamp is suitable for critical mission applications deployed in business, safety, and security products that are 5V or below. When these systems fail or are interrupted, operations may be significantly impacted. Low voltage designs are increasingly used industrial IoT (IIoT), banking, transportation, and power systems. The low voltage circuits are at risk of damage from transient voltage spikes due to sudden load changes or high transient energy levels. These events can radiate throughout the system and cause damage. Low power designs can guard against failure by using a circuit designed to limit the output voltage to a specific range, called a voltage clamp or over-voltage protection circuit.

  ALD’s SABMBOVP circuit board series protects from over-voltage by using very low-voltage precision enhancement-mode MOSFETs to improve the clamping function.  ALD’s proprietary EPAD technology was developed for low voltage, low power, high  precision linear applications. Stacking various SABMBOVP channels in series can realise different combinations of clamp voltages, advises ALD.

Both the SABMBOVP and the Zener diode options monitor the input voltage and control the external transistor switch’s gate without affecting the load circuit’s operation. The over-voltage protection circuit disconnects the load during the transient event, whereas the voltage clamp continues to power the load but clamps the voltage at a not to exceed a pre-determined voltage. Even precision Zener diodes have high leakage current and imprecise voltage ratings. Metal oxide varistors (MOVs), and most transient voltage suppressor (TVS) devices, are also impractical as they break down when voltages drop below 5V, ALD explains.

Compared to a Zener diode clamp, the SABMBOVP circuit, at less than 100nA max, has a significantly lower quiescent current than the low voltage Zener. It also has a better voltage versus current (I-V) characteristic and more precise voltages than the Zener alternative. The response time, at less than 100 nanoseconds is better than when using a Zener diode. Also, the surge current handling capability above 100 mA is better, says ALD.

As well as lower clamping voltages, compared to a Zener diode, the ALD over-voltage protection (OVP) clamps do not require additional components, such as a resistor divider, amplifier buffering circuits, and voltage regulator circuits, which are required by Zener diodes. This reduces complexity for the user as well as lowering power consumption.

Each ALD board provides two identical clamp voltage channels. The ALD SABOVP can be used as independent clamps, or they may be stacked to double the basic clamp threshold voltage. The clamp voltages on a single device will be identical boards with different clamp voltages able to be added to the stack.

The SABMBOVP family of products is available fully tested and available from Digi-Key.

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