DC/DC boost converter with resistorless current sensing

• US 7,768,242 B2
• Filed: 10/01/2007
• Issued: 08/03/2010
• Est. Priority Date: 10/01/2007
• Status: Expired due to Fees

• Current Assignee: Silicon Laboratories Incorporated
• Original Assignee: Silicon Laboratories Incorporated
• Inventors: Westwick, Alan L., Wei, Dazhi
• Primary Examiner(s): NGUYEN, MATTHEW VAN
• Application Number:
  US11/865,645
• Publication Number:
  US 20090086517A1
• Time in Patent Office: 1,037 Days
• Field of Search: 363/50, 323/222, 323/223, 323/225, 323/268, 323/271, 323282-285
• US Class Current: 323/222
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators

Abstract

A DC to DC boost converter circuit receives a DC input voltage and converts it to a DC output voltage at a different voltage level than the DC input voltage. The DC to DC boost converter includes a switching power converter for receiving the input voltage on an input and converting the input voltage to an output as the DC output voltage in response to pulse control signals. A switching controller generates the pulse control signals during a switching cycle. Current sensing circuitry limits a current passing through the switching power converter. The current sensing circuitry generates an overload signal when the current exceeds a reference value. The current sensing circuitry sensing the current with a current sensing resistor having a size of at least approximately 500 ohms.

Claims

1. A DC to DC boost converter circuit for receiving a DC input voltage and converting it to a DC output voltage at a different voltage level than the DC input voltage, comprising:

a switching power converter for receiving the input voltage on an input and converting the input voltage to an output as the DC output voltage in response to pulse control signals;

a switching controller for generating the pulse control signals during a switching cycle, the switching controller disabling at least a portion of the switching power converter responsive to an overload signal; and

current sensing circuitry for limiting a current passing through the switching power converter, wherein the current sensing circuitry generates the overload signal when the current exceeds a reference value that is independent of the output of the switching power converter, the current sensing circuitry sensing the current with a current sensing resistor having a size of at least approximately 500 ohms.

2. The DC to DC boost converter of claim 1, wherein the current sensing circuitry further comprises a comparator for comparing a first voltage associated with the current with a second voltage associated with the reference value, the comparator generating the overload signal when the first voltage exceeds the second voltage.

3. The DC to DC boost converter of claim 1, wherein the current sensing circuitry is connected to the switching power converter at a low impedance node.

4. The DC to DC boost converter of claim 1, wherein the switching power converter further comprises:

an inductor connected to receive the DC input voltage;

a load capacitor connected to a regulated voltage output node;

a zero volt turn-on rectifier connected between the inductor and the output voltage node, wherein the zero volt turn-on rectifier further includes a first transistor associated with a first mode of operation and a second transistor associated with a second mode of operation, the first and second transistors selected responsive to control signals provided by the switching controller;

a plurality of transistor switches connected in parallel between an input of the zero volt turn-on rectifier and ground, wherein a first transistor switch of the plurality of transistor switches is associated with the first mode of operation and a second transistor of the plurality of transistor switches is associated with the second mode of operation, the first and second transistor switches selected responsive to the control signals provided by the switching controller; and

switching control circuitry for controlling at least one transistor switch of the plurality of transistor switches responsive to the regulated voltage.

5. A DC to DC boost converter circuit for receiving a DC input voltage and converting it to a DC output voltage at a different voltage level than the DC input voltage, comprising:

a switching power converter for receiving the input voltage on an input and converting the input voltage to an output as the DC output voltage in response to pulse control signals, wherein the switching power converter further comprises;

an inductor connected to receive the DC input voltage;

a load capacitor connected to a regulated voltage output node;

a zero volt turn-on rectifier connected between the inductor and the output voltage node, wherein the zero volt turn-on rectifier further includes a first transistor associated with a first mode of operation and a second transistor associated with a second mode of operation, the first and second transistors selected responsive to control signals provided by the switching controller;

a plurality of transistor switches connected in parallel between an input of the zero volt turn-on rectifier and ground, wherein a first transistor switch of the plurality of transistor switches is a associated with the first mode of operation and a second transistor of the plurality of transistor switches is associated with the second mode of operation, the first and second transistor switches selected responsive to the control signals provided by the switching controller;

a switching controller for controlling at least one transistor switch of the plurality of transistor switches responsive to the regulated voltage; and

current sensing circuitry for limiting a current passing through the switching power converter, wherein the current sensing circuitry generates an overload signal when the current exceeds a reference value, the current sensing circuitry sensing the current with a current sensing resistor having a size of at least approximately 500 ohms.

6. The DC to DC boost converter of claim 5, wherein the current sensing circuitry further comprises a comparator for comparing a first voltage associated with the current with a second voltage associated with the reference value, the comparator generating the overload signal when the first voltage exceeds the second voltage.

7. The DC to DC boost converter of claim 5, wherein the current sensing circuitry is connected to the switching power converter at a low impedance node.

8. A DC to DC boost converter circuit for receiving a DC input voltage and converting it to a DC output voltage at a different voltage level than the DC input voltage, comprising:

a switching power converter for receiving the input voltage on an input and converting the input voltage to an output as the DC output voltage in response to pulse control signals;

a switching controller for generating the pulse control signals during a switching cycle, the switching controller disabling at least a portion of the switching power converter responsive to an overload signal;

current sensing circuitry connected to the switching power converter at a low impedance node for limiting a current passing through the switching power converter, wherein the current sensing circuitry generates the overload signal when the current exceeds a reference value that is independent of the output of the switching power converter, the current sensing circuitry sensing the current with a current sensing resistor having a size of at least approximately 500 ohms; and

wherein the current sensing circuitry further comprises a comparator for comparing a first voltage associated with the current with a second voltage associated with the reference value, the comparator generating the overload signal when the first voltage exceeds the second voltage.

9. The DC to DC boost converter of claim 8, wherein the switching power converter further comprises:

an inductor connected to receive the DC input voltage;

a load capacitor connected to a regulated voltage output node;

a zero volt turn-on rectifier connected between the inductor and the output voltage node, wherein the zero volt turn-on rectifier further includes a first transistor associated with a first mode of operation and a second transistor associated with a second mode of operation, the first and second transistors selected responsive to control signals provided by the switching controller;

a plurality of transistor switches connected in parallel between an input of the zero volt turn-on rectifier and ground, wherein a first transistor switch of the plurality of transistor switches is a associated with the first mode of operation and a second transistor of the plurality of transistor switches is associated with the second mode of operation, the first and second transistor switches selected responsive to the control signals provided by the switching controller; and

switching control circuitry for controlling at least one transistor switch of the plurality of transistor switches responsive to the regulated voltage.