CN-122026279-A - Switching converter, controller and control method thereof

Abstract

A switching converter, a controller thereof and a control method thereof are disclosed. The control method includes providing a comparison signal based on a feedback signal representative of an output voltage of the switching converter, determining whether an unloading event has occurred to a load of the switching converter, and providing a switch control signal based on the unloading event and the comparison signal, wherein in response to the unloading event, the switch control signal is latched in tri-state to force both the high side power switch and the low side power switch of the switching converter to be turned off until the feedback signal is below a sum of a reference signal and a ramp signal, and the switch control signal is unlatched from tri-state to turn on the high side power switch and turn off the low side power switch. The switching converter has good transient response performance and reduces overshoot of output voltage.

Inventors

• XIAO JIAJUN

Assignees

• 成都芯源系统有限公司

Dates

Publication Date

20260512

Application Date

20251027

Priority Date

20241111

Claims (20)

1. 1. A controller for a switching converter, comprising: a comparison circuit configured to provide a comparison signal based on a feedback signal representative of an output voltage of the switching converter, a reference signal, and a ramp signal; A load detection unit configured to determine whether an unloading event occurs to a load of the switching converter; a switch signal generator configured to provide a switch control signal based on the comparison signal and the unloading event, and A ramp generator coupled to the comparison circuit for providing the ramp signal, wherein In response to the load detection unit determining that the unloading event has not occurred, the switch control signal transitions to a first state to turn on a high side power switch of the switching converter and turn off a low side power switch of the switching converter when the feedback signal is lower than a sum of the reference signal and the ramp signal until an end of a conduction period, the switch control signal transitions to a second state to turn off the high side power switch and turn on the low side power switch, and wherein In response to the load detection unit determining that the unloading event occurs, the switch control signal is locked in a third state to force the high-side power switch and the low-side power switch to be off, thereby forcing the body diode of the low-side power switch to be on, until the feedback signal is below the sum of the reference signal and the ramp signal, the switch control signal is unlocked from the third state to the first state.
2. 2. The controller of claim 1, wherein the load detection unit is configured to determine whether the unloading event occurs based on the ramp signal, wherein the ramp signal is reset when the high-side power switch is turned on, the ramp signal increasing after a reset period has ended.
3. 3. The controller of claim 2, wherein the load detection unit determines that the unload event occurs when the ramp signal is clamped at a voltage level.
4. 4. The controller of claim 1, wherein the load detection unit is further configured to determine whether the unloading event occurs based on the output voltage, a switching frequency of the switching control signal, and the ramp signal, wherein if any of the output voltage, the switching frequency of the switching control signal, or the ramp signal satisfies a respective unloading indication condition, the load detection unit is configured to determine that the unloading event occurs.
5. 5. The controller of claim 4, wherein the load detection unit is configured to determine that the load event occurs once the output voltage is greater than an overshoot threshold, the load indication condition is satisfied.
6. 6. The controller of claim 4, wherein the load detection unit is configured to determine that the load event occurs once the switching frequency of the switching control signal is below a load off threshold, the load indication condition is met.
7. 7. The controller of claim 4, wherein the load detection unit is configured to determine that the load off event occurs once the ramp signal is clamped at a voltage level, the load off indication condition is met.
8. 8. A switching converter, comprising: An input node configured to receive an input voltage; an output node configured to provide an output voltage to a load; A switching circuit comprising a high side power switch and a low side power switch, wherein the high side power switch and the low side power switch are coupled in series between the input node and a reference ground, the high side power switch and the low side power switch forming a switching node; A magnetic element coupled between the switch node and the output node; A driver configured to drive the high side power switch and the low side power switch based on a switch control signal, and A controller coupled to the driver and configured to provide the switch control signal based on an unloading event and a feedback signal representative of the output voltage, wherein In response to the controller determining that the unloading event occurs, the switch control signal is locked in tri-state to force the high side power switch and the low side power switch to turn off until the feedback signal is below a sum of a reference signal and a ramp signal, the switch control signal is unlocked from the tri-state to turn on the high side power switch and turn off the low side power switch.
9. 9. The switching converter of claim 8, wherein the controller further comprises: And a load detection unit configured to determine whether the unloading event occurs based on the ramp signal, wherein the ramp signal is reset when the high-side power switch is turned on, and the ramp signal increases after a reset period is ended.
10. 10. The switching converter of claim 9, wherein the load detection unit determines that the unloading event occurs when the ramp signal is clamped at a voltage level.
11. 11. The switching converter of claim 8, wherein the controller further comprises: And a load detection unit configured to determine whether the unloading event occurs based on the output voltage, a switching frequency of the switching control signal, and the ramp signal, wherein if any one of the output voltage, the switching frequency of the switching control signal, or the ramp signal satisfies a corresponding unloading indication condition, the load detection unit is configured to determine that the unloading event occurs.
12. 12. The switching converter of claim 11, wherein the load detection unit is configured to determine that the load off event occurs once the output voltage is greater than an overshoot threshold, the load off indication condition being met.
13. 13. The switching converter of claim 11, wherein the load detection unit is configured to determine that the load off event occurs once the switching frequency of the switching control signal is below an off-load threshold, the off-load indication condition is met.
14. 14. The switching converter of claim 11, wherein the load detection unit is configured to determine that the load off event occurs once the ramp signal is clamped at a voltage level and the load off indication condition is met.
15. 15. A control method for a switching converter, comprising: Providing a comparison signal based on a feedback signal representative of an output voltage of the switching converter; determining whether an unloading event has occurred to the load of the switching converter, and Providing a switch control signal based on the unloading event and the comparison signal, wherein In response to the unloading event, the switch control signal is latched in tri-state to force both the high side power switch and the low side power switch of the switching converter to turn off until the feedback signal is below the sum of the reference signal and the ramp signal, the switch control signal is unlatched from the tri-state to turn on the high side power switch and turn off the low side power switch.
16. 16. The control method of claim 15, wherein in response to the absence of the unloading event, when the feedback signal is below the sum of the reference signal and the ramp signal, transitioning the switch control signal to a first state to turn on the high-side power switch and turn off the low-side power switch until an end of a turn-on period, transitioning the switch control signal to a second state to turn off the high-side power switch and turn on the low-side power switch.
17. 17. The control method of claim 15, further comprising determining whether the unloading event occurs based on the ramp signal, wherein the ramp signal is reset when the high-side power switch is turned on, the ramp signal increasing after a reset period has elapsed.
18. 18. The control method of claim 17, wherein the unloading event is determined to occur when the ramp signal is clamped at a voltage level.
19. 19. The control method of claim 15, further comprising determining whether the unloading event occurs based on the output voltage, a switching frequency of the switching control signal, and the ramp signal, wherein the unloading event is determined to occur if any one of the output voltage, the switching frequency of the switching control signal, or the ramp signal satisfies a corresponding unloading indication condition.
20. 20. The control method according to claim 19, wherein: Once the output voltage is greater than an overshoot threshold, satisfying the offload indication condition, determining that the offload event occurred; once the switching frequency of the switching control signal is below an unloading threshold, the unloading indication condition is satisfied, the unloading event is determined to occur, and wherein Once the ramp signal is clamped at a voltage level, the unload indication condition is satisfied, and it is determined that the unload event has occurred.

Description

Switching converter, controller and control method thereof Technical Field Embodiments of the present invention relate to electronic circuits, and more particularly, to switching converters and controllers and control methods therefor. Background In a power circuit, a power converter (e.g., a dc-dc converter) is used to provide a regulated output voltage to a load. The dc-dc converter may be a buck converter that converts an input voltage to a lower output voltage, a boost converter that converts an input voltage to a higher output voltage, or a buck-boost converter configured to perform either buck conversion or boost conversion. Load transients occur when the load current drawn by the load changes rapidly. For example, the load current increases or decreases rapidly from steady state. Conventional voltage regulation control methods cannot respond quickly to accommodate rapidly changing loads, resulting in large undershoots or overshoots in the output voltage. Disclosure of Invention Aiming at the problems in the prior art, the invention provides a switching converter with good transient response performance, and a controller and a control method thereof. According to an embodiment of the invention, a controller for a switching converter is disclosed, comprising a comparison circuit providing a comparison signal based on a feedback signal representative of an output voltage of the switching converter, a reference signal and a ramp signal, a load detection unit determining whether a load of the switching converter has an unloading event, a switching signal generator providing a switching control signal based on the comparison signal and the unloading event, and a ramp generator coupled to the comparison circuit to provide a ramp signal, wherein the switching control signal transitions to a first state to turn on a high side power switch of the switching converter and to turn off a low side power switch of the switching converter until an on-time is over, and the switching control signal transitions to a second state to turn off the high side power switch and to turn on the low side power switch, in response to the load detection unit determining that the unloading event has occurred, the switching control signal is locked in a third state to force the high side power switch and the low side power switch to be turned off, forcing a body diode of the low side power switch to be turned on until the feedback signal is below the reference signal and the switching control signal is unlocked from the third state. According to another embodiment of the present invention, a switching converter is disclosed that includes an input node that receives an input voltage, an output node that provides an output voltage to a load, a switching circuit that includes a high side power switch and a low side power switch, wherein the high side power switch and the low side power switch are coupled in series between the input node and a reference ground, the high side power switch and the low side power switch forming a switching node, a magnetic element coupled between the switching node and the output node, a driver that drives the high side power switch and the low side power switch based on a switching control signal, and a controller coupled to the driver that provides the switching control signal based on an unloading event and a feedback signal that is representative of the output voltage, wherein the switching control signal is latched in a tri-state to force the high side power switch and the low side power switch to turn off in response to the controller determining that the unloading event occurs, until the feedback signal is below a sum of the reference signal and the ramp signal, the switching control signal is unlatched from the tri-state to turn on the high side power switch and turn off the low side power switch. According to yet another embodiment of the present invention, a control method for a switching converter is disclosed, comprising providing a comparison signal based on a feedback signal representative of an output voltage of the switching converter, determining whether an unloading event has occurred to a load of the switching converter, and providing a switch control signal based on the unloading event and the comparison signal, wherein in response to the unloading event, the switch control signal is latched in tri-state to force both a high side power switch and a low side power switch of the switching converter to be turned off until the feedback signal is below a sum of a reference signal and a ramp signal, unlocking the switch control signal from tri-state to turn on the high side power switch and turn off the low side power switch. In response to an unloading event, according to embodiments of the present invention, the switch control signal is latched in tri-state to force both the high side power switch and the low side power switch to turn off, causing the magnetic element to discharge faster, re