Feature: Industrial electronics
Figure 1: Without maintenance, complex industrial processes and machines eventually fail, resulting in extended downtimes. Even after repair, repeated failures of wornout equipment continue to occur (bottom graph). Preventative maintenance schemes schedule frequent service intervals to ensure processes and machines run for long periods and machines don’t wear out, but are resource intensive (middle graph). Condition monitoring allows for extended service intervals without risk of failure whilst lowering maintenance costs (top graph)
Figure 2: Recom’s RxxCTExx Series DC-DC converters are supplied in compact surface-mount SOIC-16 packages, with a profi le under 3mm
Figure 3: Application circuit for the Recom Power RxxC05TExxS isolated DC-DC converter
resorting to a larger component size, or to maintain the power output whilst shrinking the product’s overall dimensions. For the DC-DC converter supplier, the key to off ering high
energy density is to boost the chip’s effi ciency and/or enhance its thermal performance, enabling the use of a smaller package and a higher maximum operational temperature. Recom Power DC-DC converters have an effi ciency curve
that is relatively fl at across the 20% to full output load range (Figure 4), compared to competitive devices, which oſt en exhibit poor effi ciency at low and medium output loads. T e junction temperature (Tj
top of the silicon die) for a fi xed power dissipation device such as a DC-DC regulator largely depends on the internal multipath thermal resistance (Ψjt
immediate environment. Ψjt
can escape from the component, including through the bottom of the chip via the PC board. T is parameter is diffi cult to measure outside the lab and is oſt en missing from data sheets. A good proxy for Ψjt
is θja thermal impedance (Rθja – a simpler measurement of the
directly to the ambient environment. T e units of Rθja centigrade (or Kelvin) per W (˚C/W). Hence, Tj
from the following equation: Tj
) of a component (measured centre-
) and the eff ectiveness of heat transfer to the covers all the means by which heat
Or, Tj
= Ta + ((Vin – Vout ) x Iin
) of a single heat path from the silicon die are degrees
can be estimated = ambient temperature + (power loss x thermal impedance) (1) x Rθja )
Component designers aim to minimise internal thermal impedance and maximise conductive and convective heat transfer,
www.electronicsworld.co.uk September 2022 21
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