Protect Nano

Breadboard-sized inline protection against over-voltage, under-voltage, reverse polarity and overcurrent on 3.3, 5 and 12 V rails, up to 5 A. Ships as a two-pack.

Protect Nano protects 3.3, 5 and 12 V rails against overvoltage, undervoltage and overcurrent, with up to 5 A continuous current. Its resettable electronic fuse, reverse blocking and breadboard-compatible format suit prototypes and embedded systems. Every order ships with two boards.

Description

Key Features

• Selectable Over/Under voltage Protection for 3.3, 5 and 12 V systems:
  Set your operating mode by soldering on board jumpers. When input voltage becomes invalid, the module automatically shuts off and auto-recovers when conditions normalize.
• Reverse Polarity & Reverse Current Protection:
  Features a high-side reverse-blocking MOSFET to protect against reverse current and reverse polarity faults. Also supports paralleling power supplies for redundancy (ORing).
• Adjustable Overcurrent Protection:
  Solderable jumpers let you change the overcurrent protection level either to 1, 3 or 6 A. When this triggers, the Power Good signal goes low and the module is latched-off until either the RST button is pushed or a signal is sent to the RST pin.
• Power Switch Capability:
  Toggle loads via pulling the reset (RST) pin high.
• Power Good (PG) Signal:
  Open-drain PG signal is normally pulled high to Vcc and otherwise goes LOW during a fault event, ideal for system diagnostics, alerts, or shutdown logic.
• Status LED:
  A green SAFE LED tells you that power is safely flowing through the IC.
• Thermal Shutdown feature and on-board SMD fuse:
  In the event that the maximum current draw is exceeded and the board overheats, the IC has a thermal shutdown feature that will kick in around 140-150 °C. Rest assured that there is also an 8 A series fuse on the module as a last resort in case a rapid power surge destroys the IC before the shutdown can respond.
• Soft-start feature:
  The power output gets ramped at around 1 V/ms into your circuit, which helps reduce inrush current on start up and provides a smooth turn-on.
• Breadboard and SMT Compatible, with space for terminal blocks (included):
  A small 20×26 mm footprint that fits on a standard breadboard makes this ideal for prototyping circuits. It also can be soldered to a larger PCB via its edge pads.

Over/Under Voltage Protection Behavior

Performance In 3.3, 5 And 12 V Modes

The cutoff voltages for each of the modes is shown in the figures above. Note that the module has built-in hysteresis so the cut off levels change with rising and falling voltage levels.

Important: In order for the module to turn on, the current jumper must also be soldered.

Start-up Protection Behavior

• Upon turn-on, the output voltage of the Protect Nano ramps at approximately 1.0 V/ms until the device is fully on.
• If at any point the input voltage is higher than the overvoltage cut-off (OVC) shown in the plots above, the device will enter shutdown mode and the output voltage will fall, ensuring that your circuit never sees that high voltage.
• When the output is off, the SAFE led is unlit and the Power Good (PG) signal is pulled to ground.

Continuous Conduction Mode Behavior

• If the voltage falls below the undervoltage lockout (UVLO) threshold, or rises above the OVC, the module will enter shutdown mode within a few microseconds and pull the PG signal to ground.
• If the voltage returns to a valid level as dictated by the UVLO threshold and OVC, the module will automatically turn back on and pull the PG signal to Vcc.

Creating A Redundant Supply System (Power ORing)

Multiple Protect Nano modules can be connected in parallel to create a power ORing controller.

In order for the power supplies to share the load, we have found that they generally need to be within 0.5 V or less of each other.

To operate the Protect Nano module in Paralleling mode:

1. Using one Protect Nano module per source, join the output terminals of all Protect modules to create a common bus. This is referred to as power ORing.
2. After creating the bus, connect PG to Vcc to give it a reference when it is asserted high. You can now use the PG signal from the first module as a disabling signal to pass to the reset pin of the other module(s) to create a priority power multiplexing configuration.

Resetting The Module After Overcurrent Events

The Protect Nano features a latch-off circuit breaker that can be toggled to trigger at 1, 3 or 6 A.

If the module experiences an overcurrent event and shuts off, it can be reset by pushing the reset (RST) button or by sending a 3-15 V electrical pulse to the reset pin.

Note that this board is only rated for 5 A of continuous current, the 6 A rating is a transient setting.

Additional Resources

Learn more information to effectively use the Protect Nano in a variety of applications. All content belongs to the original owners, which we have linked.

[Continuous Over-Voltage Protection Circuits]:

• Understand the pros/cons of solid state protection circuits here on our blog post.

[Intro to e-Fuses]:

• GreatScott! Explains how eFuses work and why they are awesome (YouTube)

Additional information