Selecting a Switching regulator

Switching regulators have been among the good books of designers for their good efficiency under different conditions, less heat generated, power savings and smaller size with that performance. Following are the main design points where designers start thinking of selecting a switching regulator in their power circuitry:

1. When the drop between input and output of regulator is high.

2. When the power available at the input of regulator is precious, like the case of battery. In this case efficiency must be high to eliminate power loss.

3. When the form factor of the board is less and pulling heat out of regulator is challenging. You may not be able to include large heat sinks which are required for linear regulators.

4. When the input range is high with a fixed output, then switching regulator is a must.

5. Check out the load requirements that vary over a period of time (low load current and high load current). Switching regulator is definitely not the best choice when your product is operating at low loads.

6. Give preference to a regulator which has smooth efficiency curve rather than the one which has large variations. This will give out a constant heat dissipation.

7. Keep track of the certification requirements, if a power module used comes pre certified, then give preference to the same.

8. Some certifications mandate minimum power efficiency of the switching regulator. check out those specifications.

9. Choose a switching regulator in which your efficiency is always on the higher in the entire region of  product operation.

10. Never think of too much margin at the output current side. Like for example, if your application demands a load current of 1A on the regulator, choose a regulator with current of 1.5A maximum. this helps the regulator to be within good efficiency for the entire load condition. If you choose a regulator with too much margin on output current side, efficiency may have more fluctuations in the actual operating area.

11. Think of a charge pump device (SC632 from SEMTECH) if the load current is too much on the lower side.

12. In most cases, switching regulator should always have a minimum load that is always demanded by the inductor. Otherwise excessive noise and harmonics damage the switching regulator.

13. Consider a switching regulator with in-built high and low side FETs. This will help reduce the PCB side. during this selection, thermal performance of the regulator should be eyed on.

Switching regulator basic block diagram:

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