Protect G2

A solid-state overvoltage cutoff and ideal-diode reverse protection module, adjustable from 5 to 30 V and rated for 25 A continuous.

Protect G2 combines adjustable 5–30 V overvoltage cutoff, reverse blocking and load switching up to 25 A. This compact second-generation board adds an opto-isolated fault output, with XT60 connections and an Enable input for remote control.

Description

• Adjustable Overvoltage Cutoff (5–30 V):
  Set your cutoff threshold by turning the onboard potentiometer. When input voltage exceeds the limit, Protect automatically shuts off the output and auto-recovers when conditions normalize. Typical accuracies of 3% or better are attainable by attaching a high-tolerance fixed resistor and using the given equation.
• Reverse Polarity & Reverse Current Protection:
  Acts like an ideal diode with only a 13.5 mV typical voltage drop up to 14 A. Prevents damage from incorrect power connections and supports ORing multiple supplies for redundancy and fault isolation: if one source fails, the others carry the load with no backfeed.
• Solid-State Reliability:
  No relays, no clicks. Just dependable, fast-acting MOSFET control. Designed for longevity and high reliability in demanding applications.
• Power Switch Capability:
  Use a low-current mechanical switch to toggle high-power loads via the Enable terminal block. No bulky high-current switches needed.
• Opto-isolated Fault Output:
  Open-drain fault pin goes LOW during an overvoltage event: ideal for system diagnostics, alerts, or shutdown logic.
• Dual Status LEDs:
  SAFE = Power is safely flowing. FAULT = Overvoltage fault detected and output disconnected
• Compact & Mountable:
  54.5 x 38.5 mm PCB with four M2 mounting holes. XT60 connectors make it easy to install inline with your system or stack multiple modules for power ORing.

Adjusting The Overvoltage Cutoff (OVC)

To calculate the desired cutoff voltage, use the following formula:

OVC Res = (OVC - 1.94) / 2.79

• OVC Res is in kilo-ohms (kΩ)
• OVC is your desired overvoltage shutdown voltage in volts (V)

You can measure the resistance between the test points with a multimeter while adjusting the potentiometer with a screwdriver. This provides fine-tuned control over the protection threshold.

Important: Always power off the Protect module before making adjustments to the OVC resistor to ensure current flow through the multimeter doesn’t affect its reading.

Overvoltage Protection Behavior

When the input voltage exceeds the configured OVC limit:

• The Protect module disables the output.
• The Fault LED turns on
• The FAULT signal pin is pulled low (open-drain to GND)

The module will automatically re-enable the output once the input voltage falls approximately 0.5–1 V below the OVC limit, allowing seamless recovery after transient spikes.

Paralleling Protection Behavior

⚠️ Why would you need to use a Protect module instead of just directly connecting in Parallel?

When two unequal voltage sources are connected in parallel, the higher-voltage source will push current into the lower-voltage one, trying to bring them both to the same potential.

This uncontrolled current can damage supplies that aren’t designed to accept it, as the internal control loop of the lower supply now has to fight to compensate for what the other source is doing. In the case of a battery, an unregulated and potentially dangerous current spike can flow, possibly exceeding the battery’s maximum charge current, damaging it by plating lithium and contributing to early failure.

Each Protect module has an internal comparator that senses the voltage across its pass MOSFET and switches it off within microseconds if reverse current is detected, isolating that source and protecting whatever is behind it.

A note on load sharing: ORing gives you clean redundancy and fault isolation. If one source drops out, the others carry the load with no backfeed. It does not actively balance current between sources. For the sources to share the load reasonably at all, we’ve found they generally need to be within about 0.5 V of each other; the higher source will still tend to carry more of the load until it reaches its current limit.

To operate the Protect module in paralleling (ORing) mode:

1. Use one Protect module per power source.
2. Set the OVC (overvoltage cutoff) limit on each module, or turn the OVC resistor to maximum resistance to put the cutoff at the top of its range, about 29.8 V.
3. Connect each power source to its own Protect module.
4. Join the output terminals of all Protect modules together to form the combined output.
5. (Optional) Add a switch to the Enable terminal on each module to individually turn sources on or off

Additional information