Ohmite increase power ratings and decrease thermal management requirements
New TO247 resistor has a 100W rating and New heatsink design
saves time and money
Ever aware that the threat of high temperatures caused by pushing
boundaries will result in serious malfunction and damage, Ohmite’s
engineers have spent some time investigating ways in which they can
improve thermal management which, in turn, leads to the improved
performance of their products.
Knowing that thermal management is an important part of environmental
care, and that anything which doesn’t require the use of electricity in order
to maintain acceptable temperatures is likely to be welcomed by design
engineers, Ohmite have developed a range of heatsinks which not only meet
these requirements, but also save time and money.
Consequently, the new, fully tested heatsink design has enabled Ohmite
to push the power ratings of their TO-247 resistors to new levels, resulting
in the new TEH100 which is rated at 100W at a 25ºC case temperature.
Ideally suited to power supply applications, the thick film, non-inductive power
resistor is totally encapsulated and insulated and attaches to the heatsink with
a simple, single screw mounting. Environmental issues are addressed by the
totally moulded housing.
The TEH100 has a maximum working voltage of 350V and is available in stock
resistance ranges of 0.05Ω to 1MΩ. Resistance tolerances are ±1%, ±2%, ±5%,
±10% and the linear derating is 100% at 25°C to 0% at 175°C.
Ohmite’s new heatsinks have been specifically designed for use with TO-220 and
TO-247 packages, including Ohmite’s own TAH20, TBH25, TCH35, TEH70, TEH100,
TK20 and TN15 power resistors. They feature an integrated clip for securing the
component to the heatsink without the need of a screw which saves time, money
and potential damage.
Pressure is directed on to the center of the heat dissipating device, maximising
the efficient transfer of heat and avoiding the cantilever effect which can result
from over torqueing the screw in conventional designs. The torsion spring clip also
has solderable feet to secure the assembly to the PCB.
Among the many advantages to this design are the reduced labour cost of assembly.
The spring clips make mounting holes, screws, and fasteners obsolete in the assembly
process. The spring coil also provides superior performance under shock and vibration.
Light weight and resilient, the spring clip can absorb energy as it locks the electronic
component in place. Since no screw hole needs to be tapped, stray metal particles are
eliminated as is the possibility of an accidental short circuit resulting from their presence.
Ohmite plans to release a number of derivative heatsink products based on this design
over the next few months including dual, ganged, and SMD versions.
