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Component Documentation

How to Use Resettable Fuse PTC: Examples, Pinouts, and Specs

Image of Resettable Fuse PTC

Design with Resettable Fuse PTC in Cirkit Designer

Introduction

The Resettable Fuse PTC (Positive Temperature Coefficient), manufactured by SparkFun Electronics (Part ID: COM-08357), is a versatile and reusable circuit protection device. It is designed to limit current flow in a circuit by increasing its resistance when the current exceeds a predefined threshold. Unlike traditional fuses, this component automatically resets itself once the fault condition is removed and the device cools down, eliminating the need for manual replacement.

Explore Projects Built with Resettable Fuse PTC

PT100 Temperature Sensor with Rocker Switch and Resettable Fuse

Image of soldering iron: A project utilizing Resettable Fuse PTC in a practical application

This circuit is a basic power control system that uses a rocker switch to control the flow of 220V power through a resettable fuse and a PT100 temperature sensor. The switch allows the user to turn the power on or off, while the fuse provides overcurrent protection and the PT100 sensor can be used for temperature monitoring.

Open Project in Cirkit Designer

Basic Surge Protection Circuit with Benedict Switch

Image of DC & Monitoring Box: A project utilizing Resettable Fuse PTC in a practical application

The circuit includes a Benedict Switch connected in series with a Fuse Holder and an SPD (Surge Protection Device). The SPD is also connected to a Ground reference. This configuration suggests that the circuit is designed to control power flow, protect against overcurrent with the fuse, and guard against voltage surges with the SPD, with a safe path to ground for surge dissipation.

Open Project in Cirkit Designer

PID Temperature Control System with Thermocouple and SSR

Image of IR: A project utilizing Resettable Fuse PTC in a practical application

This circuit is a temperature control system that uses a thermocouple to measure temperature and a PID controller to regulate it. The PID controller drives a solid-state relay (SSR) to control an external load, with power supplied through an AC inlet socket.

Open Project in Cirkit Designer

Arduino Mega 2560 Controlled Relay Switch for PTC Air Heater

Image of ptc air heater functional test: A project utilizing Resettable Fuse PTC in a practical application

This circuit features an Arduino Mega 2560 microcontroller connected to a 4x4 membrane matrix keypad and a 1-channel relay module. The Arduino is programmed to interact with the keypad inputs and control the relay, which switches an AC supply connected to a PTC air heater. The purpose of the circuit is likely to allow user input via the keypad to control the heating element, potentially for a temperature regulation system.

Open Project in Cirkit Designer

Explore Projects Built with Resettable Fuse PTC

Image of soldering iron: A project utilizing Resettable Fuse PTC in a practical application

PT100 Temperature Sensor with Rocker Switch and Resettable Fuse

This circuit is a basic power control system that uses a rocker switch to control the flow of 220V power through a resettable fuse and a PT100 temperature sensor. The switch allows the user to turn the power on or off, while the fuse provides overcurrent protection and the PT100 sensor can be used for temperature monitoring.

Open Project in Cirkit Designer

Image of DC & Monitoring Box: A project utilizing Resettable Fuse PTC in a practical application

Basic Surge Protection Circuit with Benedict Switch

The circuit includes a Benedict Switch connected in series with a Fuse Holder and an SPD (Surge Protection Device). The SPD is also connected to a Ground reference. This configuration suggests that the circuit is designed to control power flow, protect against overcurrent with the fuse, and guard against voltage surges with the SPD, with a safe path to ground for surge dissipation.

Open Project in Cirkit Designer

Image of IR: A project utilizing Resettable Fuse PTC in a practical application

PID Temperature Control System with Thermocouple and SSR

This circuit is a temperature control system that uses a thermocouple to measure temperature and a PID controller to regulate it. The PID controller drives a solid-state relay (SSR) to control an external load, with power supplied through an AC inlet socket.

Open Project in Cirkit Designer

Image of ptc air heater functional test: A project utilizing Resettable Fuse PTC in a practical application

Arduino Mega 2560 Controlled Relay Switch for PTC Air Heater

This circuit features an Arduino Mega 2560 microcontroller connected to a 4x4 membrane matrix keypad and a 1-channel relay module. The Arduino is programmed to interact with the keypad inputs and control the relay, which switches an AC supply connected to a PTC air heater. The purpose of the circuit is likely to allow user input via the keypad to control the heating element, potentially for a temperature regulation system.

Open Project in Cirkit Designer

Common Applications and Use Cases

Overcurrent protection in power supplies and battery packs
Short-circuit protection in consumer electronics
Protection for USB ports and peripheral devices
Automotive electronics and industrial control systems
Circuit protection in Arduino and other microcontroller-based projects

Technical Specifications

The Resettable Fuse PTC is designed to provide reliable overcurrent protection with the following key specifications:

Parameter	Value
Manufacturer	SparkFun Electronics
Part ID	COM-08357
Hold Current (I_HOLD)	500 mA (typical)
Trip Current (I_TRIP)	1 A (typical)
Maximum Voltage (V_MAX)	30 V
Resistance (R_MIN)	0.5 Ω
Resistance (R_MAX)	1.5 Ω
Maximum Time to Trip	0.5 seconds at 8 A
Operating Temperature	-40°C to +85°C
Reset Time	Varies based on ambient conditions

Pin Configuration and Descriptions

The Resettable Fuse PTC is a two-terminal device with no polarity. The terminals are typically labeled as follows:

Pin	Description
Pin 1	Input terminal (connect to power source)
Pin 2	Output terminal (connect to load)

Usage Instructions

How to Use the Component in a Circuit

Placement in Circuit: Place the Resettable Fuse PTC in series with the load you want to protect. Ensure that the current flowing through the circuit does not exceed the fuse's hold current (I_HOLD) under normal operating conditions.
Voltage Rating: Verify that the operating voltage of your circuit does not exceed the maximum voltage rating (V_MAX) of the fuse.
Connection: Connect Pin 1 to the power source and Pin 2 to the load. Since the fuse is non-polarized, the orientation does not matter.
Resetting: If the fuse trips due to an overcurrent condition, allow it to cool down and reset automatically. Ensure the fault condition is resolved before resuming operation.

Important Considerations and Best Practices

Ambient Temperature: The trip and hold currents are affected by ambient temperature. Higher temperatures may reduce the hold current, while lower temperatures may increase it.
Derating: Always derate the fuse's hold current by 20-30% to ensure reliable operation under varying conditions.
Testing: Test the circuit under normal and fault conditions to verify the fuse's performance.
Arduino Compatibility: When using the Resettable Fuse PTC with an Arduino UNO or similar microcontroller, place the fuse in series with the power supply or a specific I/O pin to protect against overcurrent.

Example Arduino Circuit

Below is an example of using the Resettable Fuse PTC to protect an Arduino UNO's 5V power supply:

/* Example: Using a Resettable Fuse PTC to protect an Arduino UNO
   This circuit places the PTC fuse in series with the 5V power supply.
   If the current exceeds the trip current, the fuse will cut off power
   to the Arduino until the fault is cleared and the fuse resets. */

// No specific code is required for the PTC fuse itself, as it operates
// passively. Ensure proper placement in the circuit as shown below:

/*
   +5V Power Supply -----> Pin 1 (PTC Fuse) Pin 2 -----> Arduino 5V Pin
   GND -------------------> Arduino GND Pin
*/

// Note: Ensure the PTC fuse's hold current is sufficient for the Arduino's
// normal operating current, including any connected peripherals.

Troubleshooting and FAQs

Common Issues and Solutions

Issue	Solution
Fuse trips frequently under normal operation	Verify that the circuit's normal operating current does not exceed I_HOLD. Derate the fuse's hold current by 20-30% for safety.
Fuse does not reset after tripping	Ensure the fault condition is resolved and allow sufficient time for the fuse to cool down.
Circuit does not power on	Check the connections to the fuse and ensure it is properly placed in series with the load.
Fuse trips at lower current than expected	Consider the effect of ambient temperature on the fuse's performance. Use a fuse with a higher hold current if necessary.

FAQs

Can the Resettable Fuse PTC be used with AC circuits?
Yes, but ensure the voltage and current ratings are suitable for the AC application.
How long does it take for the fuse to reset?
The reset time depends on the ambient temperature and the duration of the fault condition. Typically, it takes a few seconds to minutes.
Can I use multiple PTC fuses in parallel?
It is not recommended, as the current may not distribute evenly between the fuses, leading to unreliable operation.
What happens if the fuse is exposed to continuous overcurrent?
The fuse will remain in a high-resistance state until the fault is cleared and the device cools down.

By following these guidelines and best practices, the Resettable Fuse PTC (COM-08357) can provide reliable and reusable overcurrent protection for a wide range of applications.