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was key to their design brief and
hence the requirements of modern
electronic equipment, but do so at
a competitive price.
Modules do not have to
be a compromise
The controllers used in Exar’s
power modules offer the same
performance as their ICcounterparts
and provide exceptional line and
load regulation. Furthermore, to
achieve maximum efficiency at both
ends of the output current range,
operation can be switched from
the regular constant current mode
(CCM) to discontinuous conduction
mode (DCM) to save power at light
load currents. These modules also
provide all the usual protection
features, such as over current, over
temperature, short circuit and under
voltage lockout, to ensure safe
operation under abnormal operating
conditions. Additional features
include: programmable soft-start,
a programmable hiccup current
limit with thermal compensation,
flags for Power-Good and Precision
Enable, and an integrated bootstrap
diode.
Where the module approach really
wins out is in integrating the control
IC, with its rich feature set, together
with the power train components,
which have been selected for optimal
switching performance, in one
very small, cost-effective package.
The QFN packages used for these
modules (see figure 2) include large
pads that connect to key nodes in
the power train, ensuring good
Ohmic contact and minimizing EMI.
These pads also provide excellent
heatsinking for the module, which
result in the package’s low junction-
to-case thermal resistance and
superior thermal performance.
Combined with the regulator’s
intrinsic high power conversion
efficiency that minimizes internal
losses, these modules can deliver
full power with little or no de-rating
required – see figure 3. This solid
performance specification allows the
modules to be easily used in multiple
applications simply by replacing
a few passive components. This
saves development time and R&D
expense and results in a faster time-
to-market and a more competitive
product positioning.
Summary
Today’s fast paced innovative
electronic design environment
places enormous pressure on the
practicing engineer to complete his/
her designs in record times without
any sacrifice in performance or cost.
Coming to their rescue is a family
of fully integrated power modules
that are conceived, designed
and produced to help turn the
development of a power delivery
subsystem into an easy five step
process:
(1)
Know your requirement
(2)
Select the appropriate
module
(3)
Calculate the values of the
housekeeping components – see
figure 4 below
(4)
Layout your PCB
(5)
Test and verify your
prototype … then move on to your
next achievement!
The first three tasks should take
less than 30 minutes for guaranteed
Figure 5. The XR79206 achieves nearly 95% efficiency at 700kHz
switching frequency and VIN = 24V
24 l New-Tech Magazine Europe