Current-mode control in digitally controlled switched-mode
power supplies typically requires analog-to-digital (A/D) conversion of at
least two signals, voltage, and current. The complexity of voltage A/D
converters can be reduced using window A/D techniques. In conventional current
A/D conversion, however, relatively high resolution is required over a wide range
of signals, which results in increased complexity, power consumption, and cost
of the controller. This paper proposes a very simple feedback sensor capable of
high-resolution average inductor current sensing using two analog comparators
and an analog low-pass filter. The approach requires very few external components
and employs minimal digital hardware resources. A dynamic model and performance
of the average inductor current sensor are experimentally verified on a 12-V
input, 19-V output, 50-W boost converter prototype. The applicability of the
proposed sensor is demonstrated in a digitally controlled 400-W, 400-V output
Boost power factor preregulator.
No comments:
Post a Comment