Description
📝 Overview
The PN Labs Protect Nano module is a miniature electronic circuit breaker with undervoltage, overvoltage, reverse polarity and over and reverse current protection intended for use with lower-power applications. Operating at 3.3, 5 and 12 V up to 5 A of continuous current, it fits nicely onto a standard breadboard and is suitable for soldering to a larger PCB.
It sits between your power source and load, monitoring your power input conditions during an initial soft-start and subsequent operation and disconnecting the load if unsafe voltages are detected—preventing costly damage.
Use Protect Nano is an excellent choice for DIY and industrial applications.
✅ 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 Circuit Breaker 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 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 steady state 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, which are compatible for SMT processes. It also comes with 3.5 mm terminal blocks.
🚨 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.
- 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:
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.
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 to as a disabling signal to pass to the reset pin of the other module(s) to create a priority power multiplexing configuration.
🟢Normal Operation
When operating within safe voltage limits:
-
The SAFE (green) LED is illuminated
-
The Power Good (PG) signal pin is pulled high to Vcc.
- The series resistance of the module is approximately 39 mOhm.
🔌 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.
[Intro to e-Fuses]:
- GreatScott! Explains how eFuses work and why they are awesome (YouTube)
Reviews
There are no reviews yet