Have you anytime as designer asked a question to yourself the need for the highighted capacitor? Many times we follow the recommendations of the vendor in the design and tend to ignore the underlying facts. Ofcourse, in this modern design trend of finishing a product within no time, designers tend to follow guidelines without which deadlines are difficult to meet. the only thing designers do is to customize the existing design as per their design requirements.
The capacitor highlighted in the circuit is called a feed-forward capacitor. Feed Forward capacitor is included in the design parallel to the high side resitor of the resistive feedback. Some of the regulators have this capacitor internally and an extra capacitor can be used outside to improve the performance further.
The need for this capacitor is:
1. Improves the band-width of the regulator
2. Improves the stability of the capacitor
3. Improves the phase margin.
The capacitor adds a zero to the circuit there by improving the operational charactersitics of the regulator. This is a type 3 compensation.
How in real time as a designer can measure the effect of this capacitor?
Measure the transient response of the regulator and a clear improvement would be seen with this capacitor.
Feed forward cpacitor value depends on the output capacitance and inductance included in the design. Feed forward capacitor is not required if the output capacitor has large ESR, generally, electrolytic capacitors have large ESR values and if it is present in the design at the output, then feed forward capacitor is not needed.
The capacitor highlighted in the circuit is called a feed-forward capacitor. Feed Forward capacitor is included in the design parallel to the high side resitor of the resistive feedback. Some of the regulators have this capacitor internally and an extra capacitor can be used outside to improve the performance further.
The need for this capacitor is:
1. Improves the band-width of the regulator
2. Improves the stability of the capacitor
3. Improves the phase margin.
The capacitor adds a zero to the circuit there by improving the operational charactersitics of the regulator. This is a type 3 compensation.
How in real time as a designer can measure the effect of this capacitor?
Measure the transient response of the regulator and a clear improvement would be seen with this capacitor.
Feed forward cpacitor value depends on the output capacitance and inductance included in the design. Feed forward capacitor is not required if the output capacitor has large ESR, generally, electrolytic capacitors have large ESR values and if it is present in the design at the output, then feed forward capacitor is not needed.
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