Current controlling mode direct current (DC)-DC converter
View Patent ↗There is provided a current controlling mode DC-DC converter that operates in a PWM mode or a PFM mode by adjusting a turned-on time of a gate depending on power consumption of a load. The DC-DC converter includes a first comparator that receives a first input voltage and a second input voltage and outputs a first output signal, a second comparator that receives a reference voltage for mode switching and the second input voltage and outputs a second output signal, and a first logic element that outputs a reset signal for turning off a gate at a point of time when both the first output signal and the second output signal are applied. Examples may also include additional elements to facilitate mode switching.
1. A direct current (DC)-DC converter, comprising:
a first comparator configured to receive a first input voltage and a second input voltage and to output a first output signal;
a second comparator configured to receive a reference voltage configured to indicate mode switching and the second input voltage and to output a second output signal, wherein the second input voltage is based on a sensing signal and a ramp signal; and
a first logic element configured to output a reset signal based upon a determination that both the first output signal and the second output signal are applied to the first logic element, wherein the reset signal is configured to turn off a gate.
2. The DC-DC converter of claim 1 , wherein the first input voltage comprises an output voltage of an error amplifier.
3. The DC-DC converter of claim 2 , wherein the inputs of the error amplifier comprise a reference voltage for controlling a feedback voltage.
4. The DC-DC converter of claim 1 , further comprising:
an inverter configured to invert the first output signal;
a second logic element configured to receive a clock signal and an output signal of the inverter and to output a set signal; and
an Set-Reset (SR) latch configured to receive the reset signal or the set signal and configured to generate a waveform in which an on-time section of the gate has been adjusted.
5. The DC-DC converter of claim 4 , wherein the first logic configured to output the reset signal and the second logic element configured to output the set signal are AND gates.
6. The DC-DC converter of claim 4 , wherein the reference comprises a minimum on-time value of the gate that enables the DC-DC converter to operate in a Pulse Width Modulation (PWM) mode.
7. The DC-DC converter of claim 4 , wherein the DC-DC converter operates in a Pulse Width Modulation (PWM) mode in a section of gate operation in which the first input voltage is larger than the reference voltage.
8. The DC-DC converter of claim 7 , wherein in the PWM mode, the first output signal is generated later than the second output signal.
9. The DC-DC converter of claim 7 , wherein the on-time section of the gate becomes narrower based on a decrease in the first input voltage in the PWM mode.
10. The DC-DC converter of claim 7 , wherein a width of the second output signal becomes narrower based on a decrease in the first input voltage in the PWM mode.
11. The DC-DC converter of claim 4 , wherein the DC-DC converter operates in a Pulse Frequency Modulation (PFM) mode in a section of gate operation in which the first input voltage is smaller than the reference voltage.
12. The DC-DC converter of claim 11 , wherein in the PFM mode, the first output signal is generated earlier than the second output signal.
13. The DC-DC converter of claim 11 , herein in the PFM mode, the on-time section of the gate is constant.
14. The DC-DC converter of claim 11 , wherein the gate is maintained in a turned-off state in a section in which the first input voltage is smaller than an initial voltage of the second input voltage.
15. The DC-DC converter of claim 4 , wherein the DC-DC converter changes from Pulse Width Modulation (PWM) mode to Pulse Frequency Modulation (PFM) mode or from PFM mode to PWM mode in a section of gate operation in which the first input voltage is equal to the reference voltage.
16. A direct current (DC)-DC converter, comprising:
a first comparator configured to receive a first input voltage and a second input voltage and to output a first output signal;
a second comparator configured to receive a reference voltage for mode switching and the second input voltage and to output a second output signal;
a first logic element configured to output a reset signal based upon a determination that both the first output signal and the second output signal are applied to the first logic element, wherein the reset signal is configured to turn off a gate; and
a second logic element configured to output a set signal based upon a determination that a clock signal and an inverted first output signal are applied to the second logic element, wherein the set signal is configured to turn on the gate,
wherein the DC-DC converter switches between modes by outputting a reset signal for a gate at a point in time at which both the first output signal and the second output signals are applied, and
wherein the DC-DC converter changes from Pulse Width Modulation (PWM) mode to Pulse Frequency Modulation (PFM) mode or from PFM mode to PWM mode in a section of gate operation in which the first input voltage is equal to the reference voltage.
17. The DC-DC converter of claim 16 , wherein the first input voltage comprises an output voltage of an error amplifier.
18. The DC-DC converter of claim 17 , wherein the inputs of the error amplifier comprise a reference voltage for controlling a feedback voltage.
19. The DC-DC converter of claim 16 , wherein the second input voltage comprises a combined signal of a sensing signal and a ramp signal.
20. The DC-DC converter of claim 16 , wherein the DC-DC converter operates in a Pulse Width Modulation (PWM) mode in a section of gate operation in which the first input voltage is larger than the reference voltage and operates in a Pulse Frequency Modulation (PFM) mode in a section of gate operation in which the first input voltage is smaller than the reference voltage.