What are the criteria for stability of a SMPS power supply?
Transient Response: A Measure of Power Supply Stability Transient performance of a switching power supply is characterized by two main criteria: the bandwidth (BW) and phase margin (PM). A higher BW results in a faster transient response. A higher PM, on the other hand, means better stability.
Why switching regulators are more efficient?
However, the simplicity comes at the cost of low efficiency. Switching regulators on the other hand are more expensive and a little more complex internally but are significantly more efficient and capable of conducting large amounts of current without the same thermal concerns of a linear regulator.
What is loop stability?
The loop stability is determined by looking at the number of encirclements of the (-1, 0) point on this plot. For a typical analog feedback loop power supply, its open-loop transfer function is typically stable (that is, without RHP).
What is a acceptable gain margin?
In general, the phase margin of 30–60 degrees and the gain margin of 2–10 dB are desirable in the closed-loop system design. A system with a large gain margin and phase margin is stable but has a sluggish response, while the one with a small gain margin and phase margin has a less sluggish response but is oscillatory.
What are the advantages of the switching regulator?
Switching Regulator
| Advantages | Disadvantages |
|---|---|
| High efficiency Low heat generation Boost/buck/negative voltage operation possible | More external parts required Complicated design Increased noise |
What is the criteria for stability in a closed-loop control system?
By using the above stability criteria, Δ(s) is stable if the following conditions are met: K>0 and 6−K>0. Accordingly, the range of K for closed-loop stablity is given as 0
Why is switching regulator more efficient than linear regulator?
Linear regulators are simpler regulators that step down the input voltage. The goal is to set the output to a specific DC voltage. Switching regulators provide much higher efficiencies, but they can be more complex and create switching noise.
What is done in switching regulators to Minimise power dissipation during switching?
What is done in switching regulators to minimize its power dissipation during switching? Explanation: To minimize power dissipation during switching, the external transistor must be a switching power transistor and a 1mH choke smooth out the current pulses delivered to the load.
How do you tell if a system is stable or unstable?
A system is said to be stable, if its output is under control. Otherwise, it is said to be unstable. A stable system produces a bounded output for a given bounded input.
What is gain stability?
Effects of Negative Feedback If the open-loop gain decreases due to frequency or the effects of system ageing, providing that βG is still relatively large, the overall system gain does not change very much. So negative feedback tends to reduce the effects of gain change giving what is generally called “gain stability”.
Is higher gain margin better?
How do I select a switching regulator?
Factors to Consider when Selecting a Switching Regulator
- Input Voltage Range. This refers to tolerable range of input voltages supported by the IC.
- Output Voltage Range. Switching regulators usually have variable outputs.
- Output Current.
- Operating Temperature Range.
- Noise.
- Efficiency.
- Load Regulation.
- Packaging and Size.
How to identify switching regulators with instability?
As discussed earlier, the instability in a switching regulator can be verified by looking at its transient response to a load change. Figure 1 showed an example of an unstable power supply, which exhibited several oscillations on the output voltage when a load transition occurred. Figure 4 shows the bode plot for the power supply in Figure 1.
How do you limit the power of a switching regulator?
The most effective method to limit the BW of a switching regulator with an internal compensation network is using a resistor in series with the feedback pin (called a FB-series resistor). Figure 6 shows the impact of adding a FB-series resistor.
What causes instability when switching power supply?
While there are various reasons for instability, an un-tuned compensation network accounts for majority of instability issues in switching power supplies.