ERF SERIES--OVERVIEW

RESETTABLE FUSE
ERF SERIES

OVERVIEW

WHAT IS POLYMERIC PTC

The overcurrent circuit protection can be achieved with either a traditional fuse or recently developed PPTC. However, the most obvious difference between traditional fuse and PPTC is that PPTC is “resettable”. Its resistance is able to recovered, and allows to be used again.

PPTC(Polymeric positive temperature coefficient) elements compose of the polymer matrix and conductive materials. It protects the circuit by “tripping” from a low resistance to an extremely high resistance state in response to an overcurrent (see Figure 1 below).

TECHNOLOGY BASIC OF ECE RESETTABLE FUSE

ECE Resettable fuse, with wide selection of product construction type, are made of PPTC materials and most innovative PPTC technology. The resistance of the device will be increased when temperature arises. If the situations of overcurrent / overheat effect the device, the device will begin to heat up itself and its polymer matrix will change from crystalline to amorphous(see Figure 2 below). This change will dramatically increase the resistance of PPTC, and then reduce/limit the current flow in the circuit. After the fault is removed or disappeared, the resistance of device will recover in a short time and enable to be used again at normal conditions. Through this reaction, ECE resettable fuse are able to reach the purpose of circuit protection.

HOLD/TRIP CURRENT & THERMAL DERATING

Hold Current (IH) is the maximum current at which the device will not trip, and Trip Current (IT) is the minimum current at which the device will always trip. The value of Hold Current and Trip Current in ECE specifications are rated at the temperature of 23?. The following Temperature Derating Curve clearly illustrates that both IH and IT decrease while Ambient Temperature increases (see Figure 3 below).

QUICK SELECTION GUIDE

Please follow below steps to select a ECE Polymeric PTC resettable fuse to protect your circuit:

Step 1:	Determine the product construction type(Radial Leaded, Axial Leaded, or Surface Mount PTC) based on your application and circuit.
Step 2:	Confirm Operating Voltage, Operating Current, Maximum Operating Voltage, Maximum Interrupt Current, and Maximum Ambient Temperature to protect your circuit.
Step 3:	Refer to the Electrical Characteristics Table and Thermal Derating Curve to choose an appropriate Polymeric PTC resettable fuse.
Step 4:	Make sure the circuit’s Maximum Operating Voltage and Maximum Operating Current are below the standard of selected resettable fuse.
Step 5:	Verify the Time-To-Trip curve and make sure the selected resettable fuse is capable of protecting your circuit in time.
Step 6:	Ensure the dimension of selected resettable fuse is suitable for your circuit.

Finally, test and make sure the suitability of selected resettable fuse.

Model	Voltage	Current	Form factor	Application
RN	90V or below	100mA~3.75A	Radial Leaded	Telecom & Electronic Equipment
RA	60V or below	50mA~3.75A	Radial Leaded	Computer & Electronic Equipment
CA	90V or below	100mA~900mA	Radial Leaded	Cable Telephone / Cable Power Passing Tap
RB	30 V or below	900mA~9A	Radial Leaded	Computer & Electronic Equipment
BX/BU	16V/30V	750mA~2.5A	Radial Leaded	Computer & Electronic Equipment
RG	16V	2.5A~14A	Radial Leaded	Electronics, Automotive & Appliance
HX/HU	60V/250V/600V	0.08A~0.18A	Radial Leaded	Telecom Equipment
LX/LU	240VAC/DC	50mA~2.0A	Radial Leaded	Power supply Equipment
EX/EU	120VAC/DC	100mA~3.75A	Radial Leaded	Power supply Equipment
FT	36V	500mA~2.5A	Radial Leaded	Telecom & Electronic Equipment
FX/FU	16V/30V	500mA~15A	Radial Leaded	Telecom & Electronic Equipment (Operating temperatures up to 125)
AN	15V/30V	1.2A~4.2A	Axial Leaded	Rechargeable Battery & Packs
TN	24V	0.7A~3.4A	Axial Leaded	Rechargeable Battery & Packs (Preferred for NiMH chemistry batteries.)
LN	15V/20V	1.9A~7.3A	Axial Leaded	Rechargeable Battery & Packs
AD	On request	On request	Axial Leaded	Rechargeable Battery & Packs Lithium cell and battery packs & Motors
SL	6~60V	300mA~3.0A	Surface Mount	High-density PCB
SD	6~60V	100mA~3.0A	Surface Mount	High-density PCB
SM	6~60V	50mA~1.5A	Surface Mount	High-density PCB
SN	6~60V	50mA~2.0A	Surface Mount	High-density PCB
SR	6~15V	100mA~1.0A	Surface Mount	High-density PCB

Warning:

Operation beyond the specified maximum ratings or improper use may result in damage and possible electrical arcing and/or flame.
PPTC device are intended for occasional overcurrent protection. Application for repeated overcurrent condition and/or prolonged trip are not anticipated.
void contact of PPTC device with chemical solvent. Prolonged contact will damage the device performance.

Note: Specifications subject to change without prior notice.