Introduction to Digital Power Conversion
XMC4000/1000 Family
Comparison of Power Conversion Methods
Application Guide
14
V1.0, 2015-01
2.4.1
Power Conversion Oriented Peripheral Features
Here we highlight features of the XMC-family embedded peripherals that are essential for the
significant tasks required in power conversion control loops.
2.4.1.1
Sensing
Analog values are monitored, or detected upon crossing level limits, via Versatile Analog-to-Digital
Converter (VADC) channels (featuring fast compare mode), or by Analog Comparator (ACMP/CSG).
These units are interconnected with events via hardware action providers, or softwre routines via
interrupts.
The functionality of the ADCs includes:
Automatic scheduling of complex conversion sequences with priority for time-critical conversions
Synchronous sampling of up to 4 signals / Independent result registers, selectable for 8/10/12 bits
Sampling rates up to 2MHz / Flexible data rate reduction / FIR/IIR filter with selectable coefficients
Adjustable conversion speed and sampling timing
4 independent converters with up to 8 inputs w/ channel wise selectable reference voltage source
2.4.1.2
Stability and Software
An important property of conversion control loops is the frequency response of the duty-cycle-to-
output-voltage transfer function. Stabilization is provided via softwre actions in the open loop gain
paths, using DSP operations on discrete time variables, maintained by sampling at rates triggered by
a CCU (Capture and Compare Unit).
2.4.1.3
Modulation
The steady state duty-cycle-to-output-voltage transfer function is controlled by sense-modulate-drive
algorithms in hardware, with some optional add-on attributes, including (but not limited to):
Fixed-Frequency (FF)
Fixed-On-Time (FOT)
Fixed-Off-Time (FOFFT)
Conduction Mode Switching
Comparator & Slope Generation (CSG)
Blanking
Clamping
Filtering
XMC modulation modes
Voltage Mode Control
(VC)
Average Current Mode Control (ACC)
Peak Current Mode Control
(PCC)
Valley Current Mode Control
(VCC)
Zero Crossing Detection Mode (ZCD)
The XMC peripherals handle modulation dynamically, with mode-switch on changed conditions in run-
time (on load variation for example). A set of resources can be
exchanged “on-the-fly” by a Mode-Bit.
