Switching controller having programmable feedback circuit for power converters
View Patent ↗A switching controller for a boost power converter includes a switching-control circuit and a programmable feedback circuit. The programmable feedback circuit is coupled to an output of the boost power converter via a voltage divider. The programmable feedback circuit includes a current source coupled to a switch. On a light-load condition, a power-saving signal turns on the switch. The switch will conduct a programming current supplied by the current source toward the voltage divider. Furthermore, the voltage divider is externally adjustable for programming a determined level of an output voltage of the boost power converter on the light-load condition. Additionally the present invention increases system design flexibility to meet practical power-saving requirements without adding circuitries and increasing cost.
1. A switching controller for a power converter, comprising:
a switching-control circuit, for generating a switching signal; and
a programmable feedback circuit, coupled to an output of said power converter via a voltage divider, wherein said programmable feedback circuit provides a programming current to said voltage divider on a light-load condition, and said voltage divider is adjustable for programming an determined level of an output voltage at said output of said power converter in response to said programming current.
2. The switching controller as claimed in claim 1 , said programmable feedback circuit comprising:
an error amplifier, having a first terminal to receive an output signal from said voltage divider, said error amplifier further having a second terminal supplied with a feedback threshold, wherein said error amplifier generates a feedback signal in response to said output signal and said feedback threshold;
a current source, generating said programming current;
a switch, controlled by a power-saving signal, wherein said switch conducts said programming current supplied by said current source toward said voltage divider to modulate said output signal when said power-saving signal is generated on said light-load condition; and
a power management circuit, coupled to said switching-control circuit and said error amplifier for generating said power-saving signal in response thereto.
3. The switching controller as claimed in claim 2 , said power management circuit comprising:
a comparison circuit, comparing said feedback signal and a light-load threshold, wherein said light-load condition is established when said feedback signal is lower than said light-load threshold.
4. The switching controller as claimed in claim 3 , said power management circuit further comprising:
a delay circuit, receiving a pulse signal from said switching-control circuit to provide a delay period, wherein when said light-load condition sustains for longer than said delay period, said delay circuit generates said power-saving signal.
5. The switching controller as claimed in claim 2 , wherein said error amplifier is coupled to said switching-control circuit for modulating said switching signal.
6. The switching controller as claimed in claim 1 , wherein said power converter is a boost power converter.
7. A switching controller for a power converter, comprising:
a switching-control circuit, for generating a switching signal;
an error amplifier, having a first terminal coupled to an output of said power converter via a voltage divider to receive an output signal, said error amplifier further having a second terminal supplied with a feedback threshold, wherein said error amplifier generates a feedback signal in response to said output signal and said feedback threshold;
a current source, generating a programming current;
a switch, controlled by a power-saving signal, wherein said switch conducts said programming current supplied by said current source toward said voltage divider to modulate said output signal on a light-load condition; and
a power management circuit, coupled to said switching-control circuit and said error amplifier for generating said power-saving signal in response thereto.
8. The switching controller as claimed in claim 7 , wherein said voltage divider is adjustable for programming a determined level of an output voltage at said output of said power converter in response to said programming current.
9. The switching controller as claimed in claim 7 , wherein said light-load condition is established when said feedback signal is lower than a light-load threshold.
10. The switching controller as claimed in claim 9 , said power management circuit comprising:
a comparison circuit, comparing said feedback signal and said light-load threshold.
11. The switching controller as claimed in claim 10 , said power management circuit further comprising:
a delay circuit, receiving a pulse signal from said switching-control circuit to provide a delay period, wherein said delay period stabilizes a switching operation between different output voltage levels of said power converter in response to load conditions.