Do you have a clear understanding of the basic issues of these six regulators?

The regulator generates a fixed output voltage with a constant preset amplitude, regardless of whether its input voltage or load conditions change. Voltage stabilizers are divided into two categories: linear and switching. The following shares the basic problems of the six regulators.

The linear regulator uses an active (BJT or MOSFET) current-passing device (series or parallel) controlled by a high-gain differential amplifier. It compares the output voltage with a precision reference voltage source and adjusts the current-passing device to maintain a constant output voltage.

The switching regulator can convert the DC input voltage into a switching voltage applied to the power MOSFET or BJT switch. The filtered output voltage of the power switch is fed back to the circuit that can control the on and off time of the power switch, so that the output voltage can remain constant regardless of whether its input voltage or load current changes.

1. What are the topologies of switching regulators?

There are three common topologies: buck, boost, and buck/boost. Other topologies include flyback, SEPIC, Cuk, push-pull, forward, full-bridge and half-bridge topologies.

2. How does the switching frequency affect the regulator design?

The higher switching frequency means that the regulator can use smaller inductance and capacitance. This also means higher switching losses and greater circuit noise.

3. What are the losses of the switching regulator?

The power required to turn the MOSFET on and off causes losses and is related to the MOSFET gate driver. Similarly, it takes a certain amount of time to switch from the conducting state to the non-conducting state, so MOSFET power consumption is generated. In addition, the energy required to charge and discharge the MOSFET gate capacitance between the threshold voltage and the gate voltage also causes losses.

Do you have a clear understanding of the basic issues of these six regulators?

4. What are the common applications of linear and switching regulators?

Given the input and output voltages, the power consumption of the linear regulator is proportional to the output current, so the typical efficiency can be 50% or lower. By optimizing the device, the switching regulator can achieve 90% efficiency. However, the noise output of a linear regulator is much lower than that of a switching regulator with the same output voltage and current requirements. Normally, compared to linear regulators, switching regulators can drive higher current loads.

5. How does a switching regulator control its output?

A switching regulator needs to change its output voltage in some way to respond to changes in input and output voltage. One method is to use PWM to control the input of the relevant power switch, thereby controlling its switching time (duty cycle). When working, the filtered output voltage of the regulator will be fed back to the PWM controller to control the duty cycle. If the filtered output changes, the feedback applied to the PWM controller will change the duty cycle to maintain a constant output voltage.

6. Which design specifications are important for regulator ICs?

The basic parameters include input voltage, output voltage and output current. Depending on the application, other parameters may also be important, such as output ripple voltage, load transient response, output noise, and efficiency. Important parameters of linear regulators include dropout voltage, PSRR (power supply rejection ratio) and output noise.

The regulator generates a fixed output voltage with a constant preset amplitude, regardless of whether its input voltage or load conditions change. Voltage stabilizers are divided into two categories: linear and switching. The following shares the basic problems of the six regulators.

The linear regulator uses an active (BJT or MOSFET) current-passing device (series or parallel) controlled by a high-gain differential amplifier. It compares the output voltage with a precision reference voltage source and adjusts the current-passing device to maintain a constant output voltage.

The switching regulator can convert the DC input voltage into a switching voltage applied to the power MOSFET or BJT switch. The filtered output voltage of the power switch is fed back to the circuit that can control the on and off time of the power switch, so that the output voltage can remain constant regardless of whether its input voltage or load current changes.

1. What are the topologies of switching regulators?

There are three common topologies: buck, boost, and buck/boost. Other topologies include flyback, SEPIC, Cuk, push-pull, forward, full-bridge and half-bridge topologies.

2. How does the switching frequency affect the regulator design?

The higher switching frequency means that the regulator can use smaller inductance and capacitance. This also means higher switching losses and greater circuit noise.

3. What are the losses of the switching regulator?

The power required to turn the MOSFET on and off causes losses and is related to the MOSFET gate driver. Similarly, it takes a certain amount of time to switch from the conducting state to the non-conducting state, so MOSFET power consumption is generated. In addition, the energy required to charge and discharge the MOSFET gate capacitance between the threshold voltage and the gate voltage also causes losses.

Do you have a clear understanding of the basic issues of these six regulators?

4. What are the common applications of linear and switching regulators?

Given the input and output voltages, the power consumption of the linear regulator is proportional to the output current, so the typical efficiency can be 50% or lower. By optimizing the device, the switching regulator can achieve 90% efficiency. However, the noise output of a linear regulator is much lower than that of a switching regulator with the same output voltage and current requirements. Normally, compared to linear regulators, switching regulators can drive higher current loads.

5. How does a switching regulator control its output?

A switching regulator needs to change its output voltage in some way to respond to changes in input and output voltage. One method is to use PWM to control the input of the relevant power switch, thereby controlling its switching time (duty cycle). When working, the filtered output voltage of the regulator will be fed back to the PWM controller to control the duty cycle. If the filtered output changes, the feedback applied to the PWM controller will change the duty cycle to maintain a constant output voltage.

6. Which design specifications are important for regulator ICs?

The basic parameters include input voltage, output voltage and output current. Depending on the application, other parameters may also be important, such as output ripple voltage, load transient response, output noise, and efficiency. Important parameters of linear regulators include dropout voltage, PSRR (power supply rejection ratio) and output noise.

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Author: Yoyokuo