Switching regulator with soft start circuit and operation method thereof
Disclosed herein is a switching regulator with a soft start circuit for suppressing an in-rush current. The switching regulator includes a peak detector configured to receive a clock signal and detect a peak voltage of the clock signal, a comparator configured to generate a soft start signal for controlling a soft start of the switching regulator based on a result of comparing a level of the peak voltage of the clock signal to a preset reference voltage level, a counter configured to switch a state of the soft start signal at a time point when a preset soft start time arrives, and a ramp voltage generation unit configured to generate a ramp voltage by adjusting a resistance of a variable resistor based on the soft start signal.
1. A switching regulator with a soft start circuit for suppressing an in-rush current, comprising:
a peak detector configured to receive a clock signal and detect a peak voltage of the clock signal;
a comparator configured to generate a soft start signal for controlling a soft start of the switching regulator based on a result of comparing a level of the peak voltage of the clock signal to a preset reference voltage level;
a counter configured to switch a state of the soft start signal at a time point when a preset soft start time arrives; and
a ramp voltage generation unit configured to generate a ramp voltage by adjusting a resistance of a variable resistor based on the soft start signal.
2. The switching regulator of claim 1 , wherein the clock signal is a system clock output from an oscillator or a real-time clock output from a crystal clock.
3. The switching regulator of claim 1 , wherein the comparator has hysteresis.
4. The switching regulator of claim 1 , wherein the counter comprises N number of cascaded D-flip flops, and wherein a soft start time depends on the value of N.
5. The switching regulator of claim 4 , wherein the counter determines that the soft start time has arrived at the time point when an output of each of the N number of D-flip flops is in a high state.
6. The switching regulator of claim 1 , wherein a soft start time is set as a number of cycles of the clock signal.
7. A method of operating a switching regulator with a soft start circuit for suppressing an in-rush current, comprising:
receiving a clock signal and detecting a peak voltage of the clock signal;
generating a soft start signal for controlling a soft start of the switching regulator based on a result of comparing a level of the peak voltage of the clock signal to a preset reference voltage level; and
generating a ramp voltage by adjusting a resistance of a variable resistor based on the soft start signal.
8. The method of claim 7 , wherein the clock signal is a system clock output from an oscillator or a real-time clock output from a crystal clock.
9. The method of claim 7 , wherein the soft start signal remains in an on-state until an output of each of N number of cascaded D-flip flops is in a high state.
10. The method of claim 7 , wherein the soft start signal remains in an on-state during a preset cycle of the clock signal.