SI8250 Datasheet, PDF (14/30 Pages) Silicon Laboratories – DIGITAL POWER CONTROLLER

Si8250/1/2
2. Benefits of Digital Power Control
Digitally controlled power systems have the following
key advantages over analog implementations:
In-system programmability: Virtually all aspects of
digital controller behavior can be changed in
software locally or remotely, and without hardware
modification. This benefits the system in several
ways:
Hardware designs can be segregated into base
platforms (for example, by form factor or output power),
and optimized to the end application in software. This
lowers development costs by reducing the total number
of hardware designs required to address a given
application segment.
The controller's ability to readily accept change makes
possible low-cost, custom power supply versions with
relatively short lead-time.
The cost and risk of field configuration and/or updating
is greatly reduced, lowering the overhead associated
with customer support.
More advanced control algorithms: Power supply
design with fixed-function analog components leads
to many performance trade-offs. For example,
analog compensator design routinely trades stability
for higher loop bandwidth, and places the required
poles and zeros using passive components. The "if-
then-else" decision-making capability of digital
control can change loop bandwidth as needed for
optimum control response. For example the
controller can operate the compensator at a
relatively low bandwidth during steady-state
operation, but significantly extend bandwidth during
a transient. This adaptive response concept can be
applied to improve other operating parameters such
as efficiency.
Power Efficiency Optimization: In a switched mode
power supply, it is desirable to maintain high power
efficiency over a wide range of loads. Software
algorithms can optimize efficiency at every point of
line and load. For example, the software can adjust
dead time with changes load, disable synchronous
rectification at low loads, or take other measures to
maximize efficiency.
Higher operating precision: Switch timing, control
response and protection setting thresholds in analog
systems are typically determined by the values of
external passive components. These components
typically have a wide tolerance and vary with
temperature and time. Designers must allow for
these tolerances when considering worst case
operating conditions. Digital control offers tighter
parameter tolerances with greatly reduced
temperature/time variations resulting in improved
worst-case operating specifications.
Power management and power delivery functions in
a single package: Power management functions,
such as external supply sequencing, PMBus
communication support and fan control can be
performed by the digital controller, eliminating
dedicated external components.
System connectivity: PMBus and other emerging
communication protocols enable system processors
to communicate with the power supply to obtain data
and command action. For example, the system
processor may request the power supply operating
history, perform self-diagnostics or change system
settings without taking the supply off-line.
Communications with the system controller enables
notification of a pending power supply failure,
enhancing system reliability. This attribute also
reduces the cost and complexity of field
configurations and upgrades.
Higher integration/smaller size/lower cost: Many
discrete circuits can be transformed to lines of
software code, eliminating components and saving
cost. The digital controller can be used to execute
self-diagnostic routines during production test
thereby reducing test time and saving cost. The
small physical size of the Si8250 in particular
(5 x 5 mm) saves board space.
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Preliminary Rev. 0.8