When a system designer specifies a nonisolated dc/dc power
module, considering the needed input voltage range is
equally as important as considering the required performance
attributes and features. Generally, nonisolated modules
have either a narrow or a wide input voltage range. Narrowinput
modules typically have a nominal input voltage of
3.3, 5, or 12 V. For systems that operate from a tightly
regulated input bus—such as those that do not use battery
backup—a narrow-input module is often adequate since
the input remains fairly stable.
Offering greater flexibility, wide-input modules operate
within a range of 7 to 36 V, which includes the popular
12- or 24-V industrial bus. This enables a single module to
be used for generating multiple voltages. These modules
are ideal for industrial controls, HVAC systems, vehicles,
medical instrumentation, and other applications that use
a loosely regulated distribution bus. In addition, systems
powered by a rectifier/battery charger with lead-acid
battery backup almost always require wide-input modules.
System designers who choose power supplies may want
to take a close look at the latest generation of wide-input
dc/dc modules.