Boost converter

• US 20050275392A1
• Filed: 09/17/2004
• Published: 12/15/2005
• Est. Priority Date: 06/09/2004
• Status: Active Grant

• Current Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Original Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Inventors: Popescu-Stanesti, Vlad Mihail, Han, Ming Kwang, Wong, Foot Shen
• Granted Patent: US 7,615,981 B2
• Time in Patent Office: Days
• US Class Current: 323/283
• CPC Class Codes: H02M 1/0022 the disturbance parameters being input voltage fluctuations
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators

Abstract

A DC to DC converter for converting an input DC voltage to an output DC voltage. The DC to DC converter may include at least one switch, an inductor coupled to the at least one switch, and a controller capable of providing a control signal. The at least one switch may be responsive to the control signal in a first state to enter an ON state for an ON time interval, the ON time interval based on the input DC voltage and a constant. An electronic device including such a DC to DC converter and related methods are also provided.

Claims

1. A DC to DC converter for converting an input DC voltage to an output DC voltage, said DC to DC converter comprising:

at least one switch;

an inductor coupled to said at least one switch; and

a controller capable of providing a control signal, said at least one switch responsive to said control signal in a first state to enter an ON state for an ON time interval, said ON time interval based on said input DC voltage and a constant.

2. The DC to DC converter of claim 1, wherein said ON time interval is given by:

T_ON=K/V_IN, wherein T_ON is a length of said ON time interval, K is a value of said constant, and V_IN is a value of said input DC voltage.

3. The DC to DC converter of claim 2, wherein a current ripple equal to a value of a change in current level through said inductor during said ON time interval is given by:

Δ

I_L=K/L, wherein Δ

I_L is a value of said current ripple, K is said value of said constant, and L is a value of said inductor.

4. The DC to DC converter of claim 1, wherein said controller is capable of providing said control signal in a second state, said at least one switch responsive to said control signal in said second state to enter an OFF state for an OFF time interval, said OFF time interval having a length based on a comparison of a signal representative of said output DC voltage with a set voltage.

5. The DC to DC converter of claim 4, wherein said OFF time interval is equal to K divided by ((V_SET*D)−

V_IN) when said signal representative of said output DC voltage is greater than said set voltage, where K is a value of said constant, V_SET is a value of said set voltage, D is a feedback factor equal to said output voltage divided by said signal representative of said output voltage, and V_IN is a value of said input DC voltage.

6. The DC to DC converter of claim 4, wherein said OFF time interval is less than K divided by ((V_SET*D)−

V_IN) when said signal representative of said output DC voltage is less than said set voltage, where K is a value of said constant, V_SET is a value of said set voltage, D is a feedback factor equal to said output voltage divided by said signal representative of said output voltage, and V_IN is a value of said input DC voltage.

7. An electronic device comprising:

a DC to DC converter for converting an input DC voltage to an output DC voltage, said DC to DC converter comprising;

at least one switch;

an inductor coupled to said at least one switch; and

a controller capable of providing a control signal, said at least one switch responsive to said control signal in a first state to enter an ON state for an ON time interval, said ON time interval based on said input DC voltage and a constant.

8. The electronic device of claim 7, wherein said ON time interval is given by:

T_ON=K/V_IN, wherein T_ON is a length of said ON time interval, K is a value of said constant, and V_IN is a value of said input DC voltage.

9. The electronic device of claim 8, wherein a current ripple equal to a value of a change in current level through said inductor during said ON time interval is given by:

Δ

I_L=K/L, wherein Δ

I_L is a value of said current ripple, K is said value of said constant, and L is a value of said inductor.

10. The electronic device of claim 7, wherein said controller is capable of providing said control signal in a second state, said at least one switch responsive to said control signal in said second state to enter an OFF state for an OFF time interval, said OFF time interval having a length based on a comparison of said output DC voltage with a set voltage.

11. The electronic device of claim 10, wherein said OFF time interval is equal to K divided by ((V_SET*D)−

V_IN) when said signal representative of said output DC voltage is greater than said set voltage, where K is a value of said constant, V_SET is a value of said set voltage, D is a feedback factor equal to said output voltage divided by said signal representative of said output voltage, and V_IN is a value of said input DC voltage.

12. The electronic device of claim 10, wherein said OFF time interval is less than K divided by ((V_SET*D)−

V_IN) when said signal representative of said output DC voltage is less than said set voltage, where K is a value of said constant, V_SET is a value of said set voltage, D is a feedback factor equal to said output voltage divided by said signal representative of said output voltage, and V_IN is a value of said input DC voltage.

13. A method comprising:

providing a control signal to at least one switch of a DC to DC converter;

providing said control signal in a first state, said at least one switch responsive to said control signal in said first state to enter an ON state for an ON time interval; and

controlling said ON time interval based on an input DC voltage to said DC to DC converter and a constant.

14. The method of claim 13, wherein said ON time interval is given by:

T_ON=K/V_IN, wherein T_ON is a length of said ON time interval, K is a value of said constant, and V_IN is a value of said input DC voltage.

15. The method of claim 14, wherein a current ripple equal to a value of a change in current level through an inductor of said DC to DC converter during said ON time interval is given by:

Δ

I_L=K/L, wherein Δ

I_L is a value of said current ripple, K is said value of said constant, and L is a value of said inductor.

16. The method of claim 15, wherein said at least one switch comprises a low side switch of a boost DC to DC converter.

17. A boost DC to DC converter for converting an input DC voltage to an output DC voltage higher than said input DC voltage, said DC to DC converter comprising:

a high side and low side switch;

an inductor coupled to said high and low side switches; and

a controller capable of controlling a state of said high and low side switches to switch said high side switch OFF and said low side switch ON during a time ON state, said low side switch remaining ON during said time ON state for an ON time interval based on said input DC voltage and a constant, said controller further capable of controlling said state of said high and low side switches to switch said high side switch ON and said low side switch OFF during a time OFF state, said controller further capable of predicting when a current level through said inductor reaches zero and controlling said state of said high and low sides switches to switch said high side switch OFF and said low side switch OFF during a skip state to prevent a reverse current flow from said output DC voltage through said high side switch to said input DC voltage.

18. The boost DC to DC converter of claim 17, wherein said duration of said ON time interval of said low side switch during said first switch state is given by:

T_ON=K/V_IN, wherein T_ON is a length of said ON time interval, K is a value of said constant, and V_IN is a value of said input DC voltage.

19. The boost DC to DC converter of claim 18, wherein a current ripple equal to a value of a change in current level through said inductor during said ON time interval is given by:

Δ

I_L=K/L, wherein Δ

I_L is a value of said current ripple, K is said value of said constant, and L is a value of said inductor.

20. The boost converter of claim 17, wherein said controller predicts said current level through said inductor reaches zero upon expiration of said time OFF state when a duration of said time OFF state is equal to K divided by ((V_SET*D)−

V_IN), where K is a value of said constant, V_SET is a value of a set voltage, D is a feedback factor equal to said output voltage divided by a signal representative of said output voltage, and V_IN is a value of said input DC voltage.

21. The boost converter of claim 20, wherein said controller maintains said high and low side switches in said skip state after expiration of said time OFF state until said signal representative of said output voltage becomes less than V_SET.

22. The boost DC to DC converter of claim 17, further comprising feedback control circuitry capable of sensing a current level through said inductor, said feedback control circuitry comprising a switch and a comparator, said switch coupling said high side switch to an input of said comparator during said time OFF state when said high side switch is ON, said comparator comparing a voltage level based on said output voltage less a voltage drop on said high side switch with a reference voltage level and providing an output signal representative of said current level through said inductor.