Low Resistance
Metal Alloy Resistor
LRMA Series
www.bitechnologies.com www.irctt.com www.welwyn-tt.com
General Note
TT electronics reserves the right to make changes in product specification without notice or liability.
All information is subject to TT electronics’ own data and is considered accurate at time of going to print.
© TT electronics plc
09. 11
· Resistance range 1 to 100mΩ
· High temperature operation to 170°C
· Low thermal EMF version
· High power version
· Current sensing for power electronics
· RoHS compliant & halogen free
Low Resistance Metal Alloy Resistor
LRMA Series
•Resistance range 1 to 100mΩ
•High temperature operation to 170°C
•Low thermal EMF version
•High power version
•Current sensing for power electronics
•RoHS compliant & halogen free
Electrical Data
LRMA Version T (Standard) P (Power)
Size 2512 2512
Power rating @70°CW≤R01: 2, >R01: 1 3
Overload rating (5s) W≤R01: 10, >R01: 5 15
Resistance range
mΩ1 to50 3 to100
Standard values 1mΩ1, 1.5, 2, 3, 4, 5, 7, 8, 9, 10,
11,12, 15, 18, 20, 25, 30, 33, 40, 50
3, 5, 10, 11, 15,
20,25, 30, 40, 50, 80, 100
Resistance t
olerance
% 1, 5
TCR (25 to 125°C) ppm/°C >R01: ±75 >R001 & ≤R01: ±100, R001: ±275
Ambient temperature °C -55 to 170
Insulation resistance
MΩ>100
Element alloy Cu-Ni or Mn-Cu
Coating Black
LRMA Version M (Low thermal EMF) N (Inverse)
Size 1206 2512 0815
Power rating @70°CW 1 ≤R02: 2, >R02: 1 12
Overload rating (5s) W 5 ≤R02: 10, >R02: 5 5
Resistance range
mΩ5 to30 5 to40 1 to30
Standard values 1mΩ5, 10, 15, 20, 25, 30 5, 10, 20, 30, 40 1, 6, 8, 10,
15,20, 25, 30
Resistance t
olerance
% 1, 5
TCR (25 to 125°C) ppm/°C >R01: ±75, ≤R01: ±100 ±100
Ambient temperature -55 to 170°C
Insulation resistance
MΩ>100
Element alloy Mn-Cu Cu-Ni
Coating Black Green Black
Notes: 1. Non-standard values may be available for high volume requirements. 2. Requires 300mm2copper pad & trace area
Physical Data (All dimensions in mm and nominal weight in g)
Size L W C t Wt
1206 3.2 ±0.2 1.6 ±0.2 0.5 ±0.3 0.6 ±0.2 18.3
0815 2.1 ±0.25 3.75 ±0.3 0.5 ±0.2 0.7 ±0.2 14.1
2512
≤R002 2.0 ±0.2
2512
>R002
6.4 ±0.2 3.2 ±0.2
0.9 ±0.2
0.65 ±0.25 57 to 63
General Note 08/10
Welwyn Components reserves the right to make changes in product specification withoutnotice or liability
All information is subject to Welwyn’s own data and is considered accurate at time of going to print.
Welwyn Components Limited Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670 822181 •Facsimile: +44 (0) 1670 829465 •Email: info@welwyn-tt.com •Website: www.welwyn-tt.com
Low Resistance
Metal Alloy Resistor
LRMA Series
www.bitechnologies.com www.irctt.com www.welwyn-tt.com
General Note
TT electronics reserves the right to make changes in product specification without notice or liability.
All information is subject to TT electronics’ own data and is considered accurate at time of going to print.
© TT electronics plc
09. 11
Low Resistance Metal Alloy Resistor
LRMA Series
Temperature Derating
0%
20%
40%
60%
80%
100%
-30 20 70 120170
Ambient Temperature (°C)
Proportion of Pr
Typical Temperature Rise
0
20
40
60
80
100
120
0% 20% 40% 60%80% 100%
Proportion of Pr
Temperature Rise (°C)
Joint
Hot spot
Construction
Marking
The components are marked with ohmic value, e.g. “R002” = 2mΩ, “R010” = 10 mΩ.
Solvent Resistance
The component is resistant to all normal industrial cleaning solvents suitable for printed circuits.
Performance Data
Maximum (%) Typical (%)
Load at rated power (cyclic load, 1000hours at 70C) ±R 1 0.3
Short term overload (5 x rated power for 5s) ±R 0.5 0.15
Humidity (1000hours, 85°C, 85%RH) ±R 0.5 0.15
Temperature cycle (-40 to +125°C, 1000 cycles, 15 minute dwell) ±R 0.5 0.15
Resistance to solder heat (260°C ±5°C for 20s ±1s) ±R 0.5 0.3
Solderability (245°C ±5°C for 2s ±0.5s) >95% coverage
Dry heat (1000hours at 170C) ±R 0.5 0.3
Low temperature storage (1000hours at -55°C) ±R 0.5 0.15
Substrate bending (board 1.6mm, fulcrum spacing 90mm, deflection 2mm) ±R 0.5 0.3
Insulation resistance (1 minute @ 100Vdc) >100M
Thermal Performance & Mounting
Reference Pad Dimensions (mm)
Size a b L
12061.8 1.9 1.4
08157.9 1.5 0.9
2512≤R0024.0 3.1 1.3
2512>R0024.0 2.1 4.1
General Note 08/10
Welwyn Components reserves the right to make changes in product specification without notice or liability
All information is subject to Welwyn’s own data and is considered accurate at time of going to print.
Welwyn Components LimitedBedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670822181Facsimile: +44 (0) 1670829465 Email: info@welwyn-tt.com Website: www.welwyn-tt.com
Copper electrode with
nickel then tin plating
Coating (UL94-V0)
Low TCR
resistance alloy plate
The temperature rise shown is highly
dependent on mounting conditions.
Reference conditions assume 20
copper with thermal vias to multiple
layers.
The self-heating in the current tracks
should be kept negligible, or allowed
for by temperature derating.
SenseCurrent
L b
a
Low Resistance
Metal Alloy Resistor
LRMA Series
www.bitechnologies.com www.irctt.com www.welwyn-tt.com
General Note
TT electronics reserves the right to make changes in product specification without notice or liability.
All information is subject to TT electronics’ own data and is considered accurate at time of going to print.
© TT electronics plc
09. 11
Low Resistance Metal Alloy Resistor
LRMA Series
Paper Tape
Bottom Tape
Packaging
Size Tape A B W F E P1P2P0ΦD0tΦAΦBΦC Wr Tr
1206 Paper 2.0
±0.15
3.6
±0.2
8.0
±0.2
3.5
±0.05
1.75
±0.1
4.0
±0.1
2.0
±0.05
4.0
±0.1
1.5
+0.1/-0
0.84
±0.1 178 ±0.2 60 ±1 13 ±1 9±1 11.5
±1
0815 Emboss 2.6
±0.2
4.5
±0.2
12
±0.2
5.5
±0.1
1.75
±0.1
4.0
+-0.1
2.0
±0.2
4.0
±0.1
1.55
±0.05
1.1
±0.1 178 ±0.2 60 ±1 13 ±1 13 ±1 15.4
±2
2512 Emboss 3.6
±0.2
6.9
±0.2
12
±0.2
5.5
±0.05
1.75
±0.1
4.0
±0.1
2.0
±0.05
4.0
±0.05
1.5
+0.1/-0
0.85
±0.15 178 ±0.2 60 ±1 13 ±1 13 ±1 15.4
±2
Storage
Conditions: 5°C to35°C and 40% to75%RH
Shelf life: 2 years from manufacture
Processing
LRMA series resistors are suitable for both wave and IR reflow soldering. The recommended reflow profile for Pb-
free SAC305 alloy (Sn 96.5%, Ag 3%, Cu 0.5%) soldering is as follows:
Pre-heat: 60s to120s at 150°C to180°C
Soldering: 20s to40s at ≥230°C
Peak: 5s at 250°C to255°C
Ordering Procedure
Example: LRMA low thermal EMF version in 2512 size and at 10 milliohms and 1% tolerance packed in tape.
L R M A M 251 2 – R 0 1 F T 4
Type
Version
T P M N
Size
Value (use IEC62 code)
Tolerance (use IEC62 code)
F 1%
J 5%
Packing
T5 1206 5000/reel
T4 Tape0815,2512 4000/reelStandard
General Note 08/10
Welwyn Components reserves the right to make changes in product specification withoutnotice or liability
All information is subject to Welwyn’s own data and is considered accurate at time of going to print.
Welwyn Components Limited Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670 822181 •Facsimile: +44 (0) 1670 829465 •Email: info@welwyn-tt.com •Website: www.welwyn-tt.com
ΦCΦBΦA
Tr
Wr
