Granted Patent B2

US 7,126,314 · App. 11/051,586 · Granted Oct 24, 2006

Abstract

Claims (25)

1. A non-synchronous boost converter receiving an input DC voltage and providing an output DC voltage greater than the input DC voltage, the boost converter comprising:

a controller coupled to receive the input DC voltage on an input voltage terminal and generate a switched output voltage on a switched output voltage terminal, the controller further receiving an enable signal on an enable terminal and a feedback voltage on a feedback terminal, the enable signal being asserted to turn on the boost converter and being deasserted to turn off the boost converter;

a switched Schottky diode having an anode terminal coupled to the switched output voltage terminal, a cathode terminal providing the output DC voltage, and a gate terminal coupled to receive a control signal, the control signal having a first state for turning the switched Schottky diode on where the switched Schottky diode conducts current when forward biased and a second state for turning the switched Schottky diode off where forward conduction of the switched Schottky diode is blocked even when the switched Schottky diode is forward biased, the control signal being related to the enable signal;

an inductor coupled between the input DC voltage terminal and the switched output voltage terminal;

a capacitor coupled between the output voltage terminal and a first power supply voltage; and

a voltage divider coupled between the output voltage terminal and the first power supply voltage, the voltage divider providing the feedback voltage at an output node of the voltage divider.

2. The boost converter of claim 1 , wherein when the enable signal is deasserted to turn off the boost converter, the control signal has a second state for turning off the switched Schottky diode.

3. The boost converter of claim 2 , wherein the control signal is the enable signal.

4. The boost converter of claim 1 , wherein the switched Schottky diode comprises a JFET controlled Schottky diode where the forward conduction of the Schottky diode is blocked through JFET action in response to the control signal having the second state.

5. The boost converter of claim 1 , wherein the switched Schottky diode comprises an LDMOS gate controlled Schottky diode where the forward current of the Schottky diode flows through the channel of an LDMOS transistor and the forward current is blocked through gate control action of the LDMOS transistor in response to the control signal having the second state.

6. The boost converter of claim 1 , wherein the controller is formed on an integrated circuit and the switched Schottky diode is formed in the same integrated circuit in which the controller is formed.

7. The boost converter of claim 1 , wherein the controller is formed on an integrated circuit and the switched Schottky diode is formed in a second integrated circuit separate from the integrated circuit in which the controller is formed.

8. The boost converter of claim 1 , wherein the controller comprises:

a voltage reference circuit coupled to receive the input voltage and to generate a reference voltage;

a transconductance error amplifier coupled to receive the reference voltage and the feedback voltage and providing a voltage-loop control signal;

an output transistor having a control terminal coupled to receive an output control signal, a first current handling terminal coupled to the first power supply voltage through a current-sense resistor and a second current handling terminal providing the switched output voltage;

a current sense amplifier for sensing a voltage across the current-sense resistor and providing a first signal;

an oscillator providing a clock signal of a predetermined frequency;

a ramp generator coupled to receive the clock signal and generating a ramp signal;

a summer circuit coupled to sum the first signal and the ramp signal, the summer circuit providing a current-loop control signal; and

a PWM generator coupled to receive the voltage-loop control signal and the current-loop control signal and generate the output control signal driving the output transistor, the enable signal being coupled to the PWM generator for turning the PWM generator on when the enable signal is asserted and turning the PWM generator off when the enable signal is deasserted.

9. The boost converter of claim 8 , wherein the output transistor comprises a bipolar transistor.

10. The boost converter of claim 8 , wherein the output transistor comprises a MOSFET transistor.

11. The boost converter of claim 10 , wherein the output transistor comprises an N-channel MOSFET transistor.

12. The boost converter of claim 1 , wherein the voltage divider comprises a first resistor and a second resistor coupled in series between the output voltage terminal and the first power supply voltage, the common node of the first resistor and the second resistor providing the feedback voltage.

Assignments (10)