SMD resistors are seen as a component which “just exists”. Designers are usually not willing to give the part more attention – unless one fails or becomes inaccurate due to overheating or environmental problems.

Vishay’s TNPW family, represented here by family member TNPW120614K3BEEA, is an excellent candidate for all situations where high amounts of reliability are needed in a SMD package. The resistors most outstanding feature is its incredible insensitivity to moisture and heating. The datasheet claims that the parts keep their value even at 85°C and when confronted with a humidity of 85%.

Vishay prides itself on offering a wide variety of value and heat dissipation options, most of which are outlined in the table.

The TNPW family is available in various case sizes

Let the OEMsecrets team share an old hint here: designing resistor values very close to the maximum allowed amount of power dissipation is a real anti-pattern. Especially when working in automotive or motor control scenarios, spikes will crop up - in many cases, using a resistor with a sufficiently large power dissipation capability is enough to neutralize them.

Finally, developers planning to use the parts in their project are well advised to contact their distributor. Vishay is willing to send lots consisting of parts in a single date code, which - in theory - should reduce the spread of the individual parts even further.

However, it is not sure whether this is even needed. Vishay claims that every single part is optimized using a laser trimming process known from traditional precision resistors. Furthermore, parts are tested on the one by one basis, which means that that promised accuracy should be met without issues.

Author: Tam Hanna
Published: March 12, 2021