Power supply apparatus with cable voltage drop compensation

• US 9,712,052 B2
• Filed: 07/26/2015
• Issued: 07/18/2017
• Est. Priority Date: 06/08/2015
• Status: Active Grant

• Current Assignee: Acer, Inc.
• Original Assignee: Acer, Inc.
• Inventors: Lu, Chi-Nan
• Primary Examiner(s): Tran, Nguyen
• Application Number:
  US14/809,268
• Publication Number:
  US 20160357204A1
• Time in Patent Office: 723 Days
• Field of Search: 323234, 323271, 323282-285, 323318, 323349, 323351
• CPC Class Codes: G05F 1/561 Voltage to current converters amplifiers H03F
• CPC Class Codes: G05F 1/565 sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor G05F1/563 takes precedence
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators

Abstract

A power supply apparatus is provided. The power supply apparatus includes a first power pin, a second power pin, a DC output regulator, a current sensing circuit, and a compensation circuit. The first and second power pins are coupled to an external load through a first wire and a second wire respectively. The DC output regulator receives an input voltage and a feedback voltage and generates an output voltage and an output current. The current sensing circuit senses the output current and generates a sensing voltage. The compensation circuit generates a compensation voltage responding to the sensing voltage. The compensation voltage is a sum of a voltage drop on the first wire and a voltage drop on the second wire. The compensation circuit compensates the output voltage according to the compensation voltage, such that a load voltage of the external load is kept at a stable voltage value.

Claims

1. A power supply apparatus with cable voltage drop compensation, adapted for supplying power to an external load, the power supply apparatus comprising:

a first power pin, adapted for coupling to a first power contact of the external load through a first wire;

a second power pin, adapted for coupling to a second power contact of the external load through a second wire;

a direct current (DC) output regulator, receiving an input voltage and a feedback voltage and accordingly generates an output voltage and an output current;

a current sensing circuit, coupled between an output voltage terminal of the DC output regulator and the first power pin for sensing the output current, or coupled between a reference voltage terminal of the DC output regulator and the second power pin for sensing the output current, so as to accordingly generate a sensing voltage; and

a compensation circuit, coupled to the current sensing circuit so as to receive the sensing voltage, and coupled between the first power pin and the second power pin or between the output voltage terminal of the DC output regulator and the reference voltage terminal of the DC output regulator so as to generate the feedback voltage, wherein the compensation circuit generates a compensation voltage responding to the sensing voltage, and uses the compensation voltage to compensate the output voltage, wherein the compensation voltage is a sum of a voltage drop of the first wire and a voltage drop of the second wire,

wherein the compensation circuit comprises;

a voltage-to-current converter, an input terminal of the voltage-to-current converter is coupled to the current sensing circuit so as to receive the sensing voltage, and accordingly generates a set current;

a compensation resistor, coupled between the output voltage terminal of the DC output regulator and an output terminal of the voltage-to-current converter or between the first power pin and the output terminal of the voltage-to-current converter, and used to generate the compensation voltage responding to the set current; and

a voltage divider circuit, coupled between the output terminal of the voltage-to-current converter and the reference voltage terminal of the DC output regulator or between the output terminal of the voltage-to-current converter and the second power pin, and used to generate the feedback voltage responding to the compensation voltage.

2. The power supply apparatus as claimed in claim 1, wherein the current sensing circuit is coupled between the output voltage terminal of the DC output regulator and the first power pin, and the reference voltage terminal of the DC output regulator is coupled to the second power pin, the current sensing circuit comprises:

a detection resistor, coupled between the output voltage terminal of the DC output regulator and the first power pin, and used to detect the output current; and

a subtractor, coupled to two terminals of the detection resistor so as to perform a subtraction operation on voltages of the two terminals of the detection resistor, and accordingly generates the sensing voltage.

3. The power supply apparatus as claimed in claim 2, wherein the subtractor comprises:

an operational amplifier (op-amp), wherein an output terminal of the op-amp is used to generate the sensing voltage;

a first resistor, coupled between the output voltage terminal of the DC output regulator and a non-inverting input terminal of the op-amp;

a second resistor, coupled between the non-inverting input terminal of the op-amp and the second power pin;

a third resistor, coupled between the first power pin and an inverting input terminal of the op-amp; and

a fourth resistor, coupled between the inverting input terminal of the op-amp and the output terminal of the op-amp.

4. The power supply apparatus as claimed in claim 1, wherein the voltage-to-current converter comprises:

a voltage follower, a first input terminal of the voltage follower is used to receive the sensing voltage to act as a set voltage, an output terminal of the voltage follower is coupled to the output terminal of the voltage-to-current converter; and

a set resistor, coupled between a second input terminal of the voltage follower and the reference voltage terminal of the DC output regulator, and used to generate the set current responding to the set voltage.

5. The power supply apparatus as claimed in claim 4, wherein the voltage follower comprises:

an operational amplifier (op-amp), a non-inverting input terminal of the op-amp is coupled to the first input terminal of the voltage follower, an inverting input terminal of the op-amp is coupled to the second input terminal of the voltage follower; and

a transistor, a control terminal of the transistor is coupled to an output terminal of the op-amp, a first terminal of the transistor is coupled to the output terminal of the voltage follower, a second terminal of the transistor is coupled to the inverting input terminal of the op-amp.

6. The power supply apparatus as claimed in claim 1, wherein the voltage divider circuit comprises:

a first resistor, coupled between the output terminal of the voltage-to-current converter and a feedback terminal of the DC output regulator; and

a second resistor, coupled between the feedback terminal of the DC output regulator and the reference voltage terminal of the DC output regulator.

7. The power supply apparatus as claimed in claim 1, wherein the voltage-to-current converter comprises:

a voltage follower, a first input terminal of the voltage follower is used to receive the sensing voltage to act as a set voltage, an output terminal of the voltage follower is coupled to the output terminal of the voltage-to-current converter; and

a set resistor, coupled between a second input terminal of the voltage follower and the second power pin, and used to generate the set current responding to the set voltage.

8. The power supply apparatus as claimed in claim 7, wherein the voltage follower comprises:

an operational amplifier (op-amp), a non-inverting input terminal of the op-amp is coupled to the first input terminal of the voltage follower, an inverting input terminal of the op-amp is coupled to the second input terminal of the voltage follower; and

a transistor, a control terminal of the transistor is coupled to an output terminal of the op-amp, a first terminal of the transistor is coupled to the output terminal of the voltage follower, a second terminal of the transistor is coupled to the inverting input terminal of the op-amp.

9. The power supply apparatus as claimed in claim 1, wherein the voltage divider circuit comprises:

a first resistor, coupled between the output terminal of the voltage-to-current converter and a feedback terminal of the DC output regulator; and

a second resistor, coupled between the feedback terminal of the DC output regulator and the second power pin.

10. The power supply apparatus as claimed in claim 1, wherein the current sensing circuit is coupled between the reference voltage terminal of the DC output regulator and the second power pin, and the output voltage terminal of the DC output regulator is coupled to the first power pin, the current sensing circuit comprises:

a detection resistor, coupled between the reference voltage terminal of the DC output regulator and the second power pin, and used to detect the output current; and

a subtractor, coupled to two terminals of the detection resistor so as to perform a subtraction operation on voltages of the two terminals of the detection resistor, and accordingly generates the sensing voltage.

11. The power supply apparatus as claimed in claim 10, wherein the subtractor comprises:

an operational amplifier (op-amp), an output terminal of the op-amp is used to generate the sensing voltage;

a first resistor, coupled between the second power pin and the non-inverting input terminal of the op-amp;

a second resistor, coupled between the non-inverting input terminal of the op-amp and the reference voltage terminal of the DC output regulator;

a third resistor, coupled between the reference voltage terminal of the DC output regulator and an inverting input terminal of the op-amp; and

a fourth resistor, coupled between the inverting input terminal of the op-amp and the output terminal of the op-amp.