MH25 MH37
Power rating at 70°C max watts 0.25 0.5
Resistance range ohms 100K - 10M 100K - 3M
Limiting element voltage volts dc or ac peak 1,600 3,500
Isolation voltage volts 700
TCR ppm/°C 100
Resistance tolerance % 1, 2, 5
Standard values E24 and E96 preferred
Thermal impedance °C/watt 140 112
Ambient temperature range °C - 55 to 155
General Note
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 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
Electrical Data
Issue E · 10.05
A subsidiary of
TT electronics plc
Welwyn Components
191
Construction
Thin film material is sputtered on to high grade ceramic rods.
Nickel plated steel caps are force fitted and the termination
wires are welded to the caps. The value is obtained by a
helical cut in the film and finally the resistor body is protected
by a cement protection applied so that the terminations
remain completely clear.
Marking
1% tolerance resistors are colour coded with 5 bands.
2% and 5% tolerance have 4. Band IEC 62 colours are used.
Terminations
Material Solder-coated copper wire.
Strength The terminations satisfy the requirements of
IEC 68.2.21.
Solderability The terminations meet the requirements of
IEC 115-1, Clause 4.17.3.2
Solvent resistance
The body protection and marking are resistant to all normal
industrial cleaning fluids suitable for printed boards.
Dimensions (mm) and Weight (g)
PCB Min
mounting
Bend
Type L max D max f min d nom centres Radius Wt.nom
MH25 6.2 2.5 21.0 0.6 10.2 0.6 0.3
MH37 9.0 3.7 19.6 0.8 12.7 1.2 0.5
Physical Data
L
Df
d
High Voltage
Metal Film Resistors
MH Series
•BSEN 60065 Approval for MH37
in value range 680K to 3M
•High working voltage to 3.5KV
•Small size
•High pulse load capability
•Robust cement coating
•Value up to 10M
High Voltage
Metal Film Resistors
MH Series
© 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 Issue E · 10.05
Welwyn Components
192
52
f1f2
6
5
Body Location f1 – f2≤ 1.4 mm
6
Packaging
All MH series resistors are supplied tape packed ready for
loading on automatic sequencing and insertion machines.
Component wires will not protrude beyond the outside edge
of the tape.
Alternative packing available by request.
Lead Formed Resistors can also be supplied. Standard options
of Lancet, Radial and Goal Post forming are shown in the
Lead Form information sheet.
Application Notes
To ensure reliable performance at high voltages care should
be taken to avoid potential sources of ionic contamination
contacting the resistor body, for example, flux applied by
spraying, encapsulation materials or contaminants from the
environment of use.
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Load at rated voltage : 1000 hrs at 70°C ∆4.05.1%R
C°551 ta oreZC°07 ta rewop detar morf gnitareD
Overload ∆52.00.1%R
56 days at DHSS ∆2.05.1%R
Climatic ∆2.05.1%R
Climatic category 55/155/56
Temperature rapid change ∆50.05.0%R
Resistance to solder heat ∆50.05.0%R
Vibration and bump ∆50.05.0%R
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Performance Data
Ordering Procedure
Example: MH25 at 4.7 megohms and 1% tolerance in ammo pack box of 5000 pieces –
M H 2 5 – 4 M 7 F I
Type
Value (use IEC62 code)
Tolerance (use IEC62 code)
F
1%
G
2%
J
5%
Packing
I
Ammo
MH25
5000/box
MH37
2500/box