SMD1140 Fast - Acting Surface Mount Fuse 11.6x4x4mm 1A 250V 72V UL 248-14 475 Series

UL 248-14 475 Series SMD1140 Fast-Acting Surface Mount Fuse 11.6x4x4mm 1A 250V 72V

Description

The SMD Fuse is a very small, Wire-in-Air (WIA) square shape surface mount fuse which is very suitable for the secondary side circuit over-current protection applications and is designed for PCB using surface mount technology.

Size (mm)

Main Characteristics

Time vs Current Characteristics: UL-248-14

Specification

Note:

(1) Permissible continuous operating current is ≤100% at ambient temperature of 23°C (73.4°F)

(2) The current values used for calculating I2T should be within the standard range of 10ms.

Features

Very fast acting
Small size
Wide range of current rating available (0.062A to 20A)
Wide operating temperature range
Low temperature rerating
RoHS compliant and Halogen Free

Applications

Notebook PC
LCD/PDP TV
LCD monitor
LCD/PDP panel
LCD backlight inverter
Portable DVD player
Power supply
Networking
PC server
Cooling fan system
Storage system
Telecom system
Wireless basestation
White goods
Game console
Office Automation equipment
Battery charging circuit protection
Industrial equipment

Parameters

Consider the following parameters when choosing a proper AEM SolidMatrix® and AirMatrix® fuse:
1. Maximum Steady State operating current
2. Maximum operating temperature
3. Waveform of maximum transient pulse current
4. Pulse cycle
5. Overload current and corresponding breaking time
6. Possible maximum fault current in applications
7. Maximum operating voltage
8. Dimension
9. Compliance standard

Example

The following example describes the previous selection process.

Circuit parameters:
1. Maximum steady operating current: I=0.6A
2. Operating temperature: +65°C
3. Waveform of maximum transient pulse current (Sine wave)maximum current Ip =45.5A, pulse width t=120Sec
4. Required number of pulses to withstand: 100,000
5. Overload current and corresponding breaking time: I=10A, 60Sec
6. Possible maximum fault current in application: 50A
7. Maximum operating voltage: 12V
8. Dimension: 1206
9. Compliance standard: UL Recognized

Calculation of steady state parameters:
The minimum rated current of the fuse to meet the requirements of steady parameters is In >= I/0.75 (current derating factor)/K (temperature derating factor)= 0.6/75%/90% =0.89A. In this way, the fuse with its rated current larger than or equal to 1A is acceptable.

Calculation of transient parameters:
I2t value:
Refer to the formula in Table 1 to calculate the I2t value of pulse current. The impact of ambient temperature to pulse withstanding capability should be considered at the same time.
I2t value of pulse current:
Ip2t =0.5x(45.52A)2x120µSec= 0.1243A2Sec
This application requires the fuse to withstand 100,000 pulses under +65°C, and thus pulse and temperature derating should be considered concurrently.
If2t >= Ip2t /P(Pulse derating) /K(Temperature derating) = 0.1243/20%/90%=0.69A2Sec
Comparing the I2t vs t curve in AEM's catalog, the specification of the fuse (If2t>0.69A2Sec; t=120µSec) is not less than 3.5A If2t value. Therefore, F1206HI series fuses with the rated current larger than or equal to 3.5A are acceptable.

Protection performance:
The fuse should blow within 60s when the current is 10A. AEM's F1206HI series feature a clear time of less than 60s when the current is twice overloaded (200%). Therefore a fuse with rated current less than 5A may be selected.

Conclusion:
In conclusion, the F1206HI series from 3.5A to 5A may satisfy all product specifications as required above.Considering that the fluctuation of parameters of other comp