Document
Special Application Fuses
Intrinsically Safe > Surface Mount > 308 Series
308 Series 30V Intrinsically Safe Fuse
Pb RoHS
Agency Approvals
Agency
Agency File Number DEMKO 15 ATEX 1439U
II 1 G Ex ia IIC E358130
IECEx UL 15.0011U Ex ia IIC
Ampere Rating 0.250A – 1.5A 0.250A – 1.5A 0.250A – 1.5A
Reference Standards
Certification ATEX IECEx UL
cUL
Standards
EN 60079-0, EN 60079-11 IEC 60079-0, IEC 60079-11
UL 913, UL 60079-0, UL 60079-11
CAN/CSA C22.2 No. 157, CAN/CSA C22.2 No. 60079-0, CAN/CSA C22.2 No. 60079-11
Description The 308 Series offers a range of surface mountable encapsulated fuses certified as intrinsically safe components that can be used in hazardous locations. Ideal for use in oil, gas, mine, chemical, pharmaceutical and process industries, the 308 Series surface mountable fuse was designed to limit the energy and temperature generated during its operation. The fuse design and its encapsulant are suitable for use in intrinsically safe apparatus and associated apparatus for peak voltage not exceeding 30V.
Features
• Surface Mountable
• Encapsulated and sealed (0.7mm minimum)
• Designed for operation in a range of hazardous area applications requiring 30V peak
• RoHS compliant and Pb-Free
• Fully compatible with lead-free solder alloys and higher temperature profiles associated with lead-free assembly
• Global hazardous locaiton (haz loc) certificaitons
Applications
• Testing, measuring or processing electronic and electrical equipment
• Motor controllers
• Communication handsets/ two-way radios
• Process control and
automation • Sensors • Lighting • Flow/gas meters
Electrical Characteristics for Series
% of Ampere Rating
100% 250%* 350%** * Applicable to 750mA - 1.5A ** Applicable to 250mA - 1.5A
Opening Time
4 Hours, Minimum 120 Seconds, Maximum 60 Seconds, Maximum
Electrical Specifications by Items
Catalog Number
Ampere Rating
(A)
Amp Code
Interrupting Rating
Nominal Melting I2t (A2 Sec.)
Minimum Cold Resistance at -20°C (Ohms)
Minimum Cold Resistance at -40°C (Ohms)
0308.250 0308.375 0308.500 0308.750 0308001. 03081.25 030801.5
0.250 0.375 0.500 0.750 1.00 1.25 1.50
.250 .375 .500 .750 001. 1.25 01.5
50A@24VAC 50A@30VDC
0.004 0.010 0.022 0.048 0.100 0.220 0.3
1.856 1.022 0.712 0.520 0.226 0.240 0.182
1.821 1.006 0.676 0.511 0.216 0.236 0.144
Notes: 1. The fuse must be mounted so that creepage and clearance distances aren’t impaired in any way. 2. The fuse is suitable for use in intrinsically safe equipment and associated apparatus for voltage not exceeding 30V peak. 3. Maximum surface temperature rise at 170% rated current: 250-375mA = 23°C, 500mA = 35°C, 750mA = 53°C, 1A = 38°C, 1.25-1.50A = 96°C. 4. Minimum Cold Resistance at -30°C is available upon request.
Nominal Cold Resistance at 25°C (Ohms)
2.290 1.330 0.908 0.665 0.420 0.318 0.209
Agency Approvals
X XX X XX X XX X XX X XX X XX X XX
© 2019 Littelfuse, Inc. Specifications are subject to change without notice.
Revised: 12/04/19
Special Application Fuses
Intrinsically Safe > Surface Mount > 308 Series
0.250A 0.375A 0.500A 0.750A 1.00A 1.25A 1.5A
PERCENT OF RATING
Temperature Rerating Curve
140
120
100
80
60
40 -85 -65 -45 -25 -5 15 35 55 75 95 115 135 155 TEMPERATURE (ºC)
Notes: 1. Re-rating depicted in this curve is in addition to the standard re-rating of 20% for continuous operation. Example: For continuous operation at 55°C, the fuse should be rerated as follows: I = (0.80)(0.90)IRAT = (0.72)IRAT 2. The temperature rerating curve represents the nominal conditions. For questions about temperature rerating curve, please consult Littelfuse technical support for assistance.
Time in Seconds
Average Time Current Curves
100.000 10.000 1.000 0.100
Soldering Parameters
Reflow Condition
- Temperature Min (Ts(min))
Pre Heat
- Temperature Max (Ts(max))
- Time (Min to Max) (ts)
Average ramp up rate (Liquidus Temp (TL) to peak
TS(max) to TL - Ramp-up Rate
Reflow
- Temperature (TL) (Liquidus) - Temperature (tL)
Peak Temperature (TP)
Time within 5°C of actual peak Temperature (tp)
Ramp-down Rate
Time 25°C to peak Temperature (TP) Do not exceed
Pb – Free assembly 150°C 200°C 60 – 180 secs 3°C/second max. 3°C/second max. 217°C 60 – 150 seconds 260+0/–5 °C 30 Sec Max 6°C/second max. 8 minutes max. -
Temperature
0.010 0.001
0.01
0.1 1 Current in Ampers
10
100
TP
TL TS(max)
Ramp-up
TS(min)
25
Preheat
tS
time to peak temperature (t 25ºC to peak)
tP
Critical Zone TL to TP
tL
Ramp-down
Time
© 2019 Littelfuse, Inc. Specifications are subject to change without notice.
Revised: 12/04/19
Special Application Fuses
Intrinsically Safe > Surface Mount > 308 Series
Dimensions (mm)
GATE SEE MARKING CODE 5.40 +-00.1.042
3.65 +-0.0.1145
3.80 +-00.1.145
Part Marking System
Amp Code
0.250 0.375 0.500 0.750 001.0 1.25 01.5
Marking Code
D E F G H J K
2
.
20
+0.50 -0.20
RECOMMENDED PCB LAND PATTERN 2.45
0. 20 MIN 2.34
.