## Overview of the RSR-02-R The **RSR-02-R** is a specific electronic component typically identified as a **Radial Lead Resettable Fuse** (also known as a Polymeric Positive Temperature Coefficient or **PPTC** device). These parts are used for overcurrent protection in electronic circuits. Unlike traditional fuses that "blow" and must be replaced, the RSR-02-R increases its resistance significantly when an overcurrent occurs, then resets once the fault is cleared and the temperature drops. --- ### Technical Specifications Below is a breakdown of the typical electronic characteristics for the RSR-02-R series: | Parameter | Description | Typical Value | | :--- | :--- | :--- | | **$I_{hold}$** | Maximum current the device will not trip at $23^\circ C$ | 0.20 A (200mA) | | **$I_{trip}$** | Minimum current that will cause the device to trip | 0.40 A (400mA) | | **$V_{max}$** | Maximum voltage the device can withstand | 30V - 60V (Series dependent) | | **$I_{max}$** | Maximum fault current the device can safely handle | 40 A | | **$P_d$** | Power dissipated from the device in tripped state | 0.41 W | | **Temperature Range** | Operating environment capability | $-40^\circ C$ to $+85^\circ C$ | --- ### Key Electronic Functions 1. **Overcurrent Protection:** It acts as a gatekeeper. If the current exceeds $I_{trip}$, the internal polymer expands, breaking the conductive chain and stopping the flow of electricity. 2. **Automatic Reset:** Once the power is removed and the device cools down, the polymer shrinks, the conductive pathways re-establish, and the circuit functions normally again. 3. **Resistance Change:** * **Normal State:** Very low resistance (milliohms). * **Tripped State:** Very high resistance (kilo-ohms). --- ### Physical Construction The "R" suffix and "Radial" designation refer to the physical lead configuration: * **Encapsulation:** Cured, flame-retardant epoxy polymer (meeting UL 94V-0 requirements). * **Leads:** Two tin-plated copper wires extending from the bottom of the disc. * **Form Factor:** Disc-shaped, small footprint for Through-Hole Technology (THT) on PCBs. --- ### Common Applications The RSR-02-R is frequently found in: * **USB Ports:** Protecting against shorts in peripheral devices. * **Battery Packs:** Preventing damage from accidental short circuits. * **Security Systems:** Protecting sensors and control panels. * **Transformers:** Used as secondary protection for low-voltage power supplies. ---