Time-sharing current sense circuit for a multi-phase converter

• US 20050140347A1
• Filed: 04/21/2004
• Published: 06/30/2005
• Est. Priority Date: 12/26/2003
• Status: Active Grant

• Current Assignee: Richtek Technology Corporation (MediaTek, Inc.)
• Original Assignee: Richtek Technology Corporation (MediaTek, Inc.)
• Inventors: Ho, Hsin-Hsin, Chen, Jiun-Chiang, Tai, Liang-Pin, Wang, Hung-I
• Granted Patent: US 6,960,905 B2
• Time in Patent Office: Days
• US Class Current: 323/282
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02M 3/1584 with a plurality of power processing stages connected in parallel

Abstract

In a time-sharing current sense circuit for a multi-phase converter, a common transconductive amplifier is selectively connected to the channels of the converter power stage by a plurality of first switches under the control of a set of control clocks to detect the channel current of a selected channel among the channels so as to generate a sense current, and a sense current generated by the common transconductive amplifier from the sensed channel current is switched by a plurality of second switches under the control of the same control clocks to connect to one of a plurality of sampling-and-holding circuits each corresponding to one of the channels to generate a current sense signal to modulate the channel current of the selected channel.

Claims

1. A time-sharing current sense circuit for a multi-phase converter having a plurality of channels each including a high-side switch connected between an input voltage and a phase node, a low-side switch connected between said phase node and a system reference, and an inductor connected between said phase node and a converter output for a channel current flowing therethrough, said time-sharing current sense circuit comprising:

a common transconductive amplifier for generating a sense current representative of said channel current for each of said plurality of channels;

a plurality of first switches each between said common transconductive amplifier and one of said plurality of channels for switching between said channel currents to said common transconductive amplifier;

a plurality of sampling-and-holding circuits each for generating a current sense signal responsive to said sense current to modulate respective one of said channel currents; and

a plurality of second switches for switching said sense current to one of said plurality of sampling-and-holding circuits.

2. A time-sharing current sense circuit of claim 1, further comprising a plurality of sense resistors each connected between one of said inductors and said converter output for sensing said respective one of said channel currents.

3. A time-sharing current sense circuit of claim 2, wherein said common transconductive amplifier has an inverting input connected to said converter output, and a non-inverting input selectively connected to one of said plurality of sense resistors by said plurality of first switches.

4. A time-sharing current sense circuit of claim 3, further comprising a voltage-to-current resistor connected between said inverting input and said converter output.

5. A time-sharing current sense circuit of claim 1, further comprising a plurality of sense resistors each connected between one of said low-side switches and said system reference for sensing said respective one of said channel currents.

6. A time-sharing current sense circuit of claim 5, wherein said common transconductive amplifier has an inverting input selectively connected to one of said plurality of sense resistors by said plurality of first switches, and a non-inverting input connected to said system reference.

7. A time-sharing current sense circuit of claim 6, further comprising a plurality of voltage-to-current resistors each connected between said inverting input and one of said plurality of sense resistors.

8. A time-sharing current sense circuit of claim 1, wherein each of said low-side switches has an ON-resistance serving as a sense resistor for sensing said channel current thereof.

9. A time-sharing current sense circuit of claim 8, wherein said common transconductive amplifier has an inverting input selectively connected to one of said phase nodes by said plurality of first switches, and a non-inverting input connected to said system reference.

10. A time-sharing current sense circuit of claim 1, further comprising a set of control clocks for switching said plurality of first and second switches.