- 2074 Chaitra · 3 marks
Short note: Switching regulators
Short answer
Switching regulators use a transistor as a switch with PWM to control average output voltage. Basic types: buck (Va=kVs), boost (Va=Vs/(1-k)), buck-boost (Va=-kVs/(1-k)). They offer high efficiency (80-95%), small size, but produce switching noise and require more complexity.
Write a short note on switching regulators.
A switching regulator is a DC voltage regulator in which a transistor (BJT/MOSFET) is operated as a switch (fully ON or fully OFF) at high frequency (20 kHz – 1 MHz), instead of in the linear region. The output voltage is controlled by the duty cycle k = Ton/T using PWM, and an L-C filter smooths the output.
Vs -->[SWITCH]-->[L-C FILTER]--+--> Vo
^ |
| [divider]
[PWM CONTROL]<--[ERROR AMP]<--Vref
The error amplifier compares a fraction of Vo with a reference; the PWM controller changes k to keep Vo constant against changes in input or load.
Basic types:
| Type | Output | Relation |
|---|---|---|
| Buck | Va < Vs | Va = k·Vs |
| Boost | Va > Vs | Va = Vs/(1 − k) |
| Buck-boost | Inverted, < or > Vs | Va = −k·Vs/(1 − k) |
| Cuk | Inverted, < or > Vs | Va = −k·Vs/(1 − k) |
Advantages: high efficiency (80–95 %), since the switch dissipates little power; small size and weight; can step up, step down or invert the voltage.
Disadvantages: output ripple and switching noise (EMI), more complex circuit, slower transient response than linear regulators.
✓ Answer checked by Claude Opus 5.5 (high effort)