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Charging circuit for parallel charging in multiple battery systems

Charging circuit for parallel charging in multiple battery systems description/claims

This application is a Continuation Application of application Ser. No. 11/425,244 filed Jun. 20, 2006, now U.S. Pat. No. 7,414,381, the teachings of which are incorporated herein by reference, which is a Continuation of application Ser. No. 10/648,891 filed Aug. 27, 2003, now U.S. Pat. No. 7,064,521, the teachings of which are incorporated herein by reference, which itself is a continuation-in-part application of U.S. Nonprovisional application Ser. No. 10/364,228 filed Feb. 11, 2003, now U.S. Pat. No. 6,977,482, the teachings of which are incorporated herein by reference, and claims the benefit of U.S. Provisional Application No. 60/457,826 filed Mar. 26, 2003 and U.S. Provisional Application No. 60/484,635 filed Jul. 3, 2003, the teachings of both of which are also incorporated herein by reference. Application Ser. No. 10/648,891 filed Aug. 27, 2003, now U.S. Pat. No. 7,064,521, is also a continuation-in-part of application Ser. No. 10/618,901 filed Jul. 14, 2003, now U.S. Pat. No. 6,861,823, the teachings of which are incorporated herein by reference, which itself is a continuation of application Ser. No. 10/328,466 filed Dec. 23, 2002, now U.S. Pat. No. 6,611,129, the teachings of which are incorporated herein by reference, which itself is a continuation of application Ser. No. 09/948,828 filed Sep. 7, 2001, now U.S. Pat. No. 6,498,461, the teachings of which are incorporated herein by reference, all of which claim the benefit of Provisional Application Ser. No. 60/313,260 filed Aug. 17, 2001, the teachings of which are incorporated herein by reference.

The present invention relates to charging circuits and in particular to charging circuits for charging multiple batteries in parallel.

Selector circuits are typically utilized in a power supply block for various electronic devices. Such selector circuits are generally designed to select between a DC power source, e.g., an AC/DC adapter, and a rechargeable battery. In various electronic devices like a laptop computer, such selector circuits are typically controlled via control signals communicated via a System Management Bus (SMBus) according to a specified protocol. In addition, such selector circuits typically cannot independently ascertain, correct, and notify other components in the power supply block of a power crises condition. In addition, such selector circuits are not configured to accept control signals from an associated host power management unit.

Charging circuits are typically utilized to regulate battery charging conditions when a selector circuit has selected one or more batteries for charging. Most charging circuits for use with multiple batteries do not permit charging multiple batteries in parallel. For those charging circuits that do permit charging of multiple batteries, only the total battery charging current is controlled and maintained below a maximum limit. Hence, battery charging time is increased. For example, if two similar batteries were to be charged in parallel in such an instance, the average charging current per battery would only be half of the maximum permitted even if the maximum power level from the associated DC power source (e.g., an AC/DC adapter) is not reached. Accordingly, there is also a need in the art for a charging circuit with enhanced parallel charging capabilities.

A charging circuit for controlling a system charging parameter provided to a host of batteries, wherein the host of batteries includes at least a first battery and second battery that may be coupled in parallel is provided. The charging circuit consistent with the invention includes a first path configured to monitor a first battery charging current level provided to the first battery, a second path configured to monitor a second battery charging current level provided to the second battery; and a regulating circuit configured to reduce the system charging parameter provided to the host of batteries if the first charging current exceeds a first predetermined maximum charging current level or the second charging current exceeds a second predetermined maximum charging current level.

A method for controlling a system charging parameter provided to a host of batteries, wherein the host of batteries comprises at least a first battery and second battery that may be coupled in parallel is provided. The method consistent with the invention includes: monitoring a first battery charging current level provided to the first battery; monitoring a second battery charging current level provided to the second battery; and reducing the system charging parameter provided to the host of batteries if the first charging current level exceeds a first predetermined maximum charging current level or the second charging current exceeds a second predetermined maximum charging current level.

According to another aspect of the invention, there is provided a charging circuit for regulating an output parameter of a DC to DC converter. The output parameter of the DC to DC converter providing power to a host of batteries, wherein the host of batteries comprises at least a first battery and second battery that may be coupled in parallel. The charging circuit consistent with the invention includes: a first path configured to monitor a first battery charging current level provided to the first battery; a second path configured to monitor a second battery charging current level provided to the second battery; a third path configured to monitor a first battery charging voltage level provided to the first battery; and a fourth path configured to monitor a second battery charging voltage level provided to the second battery. The charging circuit also includes a regulating circuit configured to reduce the output parameter of the DC to DC converter if one of the first battery charging current level, the second battery charging current level, the first battery charging voltage level, and the second battery charging voltage level exceeds an associated predetermined maximum level.

According to yet another aspect of the invention there is provided an electronic device. The electronic device consistent with the invention includes: a power management unit configured to provide an output signal representative of at least a first predetermined maximum charging current level and a second predetermined maximum charging current level; a host of batteries including at least a first battery and a second battery coupled in parallel; and a charging circuit for controlling a system charging parameter provided to the host of batteries. The charging circuit includes: a first path configured to monitor a first battery charging current level provided to the first battery and compare the first battery charging current level to the first predetermined maximum charging current level; a second path configured to monitor a second battery charging current level provided to the second battery and compare the second battery charging current level to the second predetermined maximum charging current level; and a regulating circuit configured to reduce the system charging parameter provided to the host of batteries if the first charging current exceeds the first predetermined maximum charging current level or the second charging current exceeds the second predetermined maximum charging current level.

In yet a further aspect of the invention, there is provided an electronic device that may be powered by one or more of a host of rechargeable batteries or a DC power source. The electronic device consistent with the invention includes: a power management unit (PMU) configured to run a power management routine; a charging circuit configured to control charging of the host of rechargeable batteries, wherein the host of batteries includes at least a first battery and a second battery coupled in parallel, the charging circuit including: a first path configured to monitor a first battery charging current level provided to the first battery and compare the first battery charging current level to the first predetermined maximum charging current level; a second path configured to monitor a second battery charging current level provided to the second battery and compare the second battery charging current level to the second predetermined maximum charging current level; and a regulating circuit configured to reduce the system charging parameter provided to the host of batteries if the first charging current exceeds the first predetermined maximum charging current level or the second charging current exceeds the second predetermined maximum charging current level; and a selector circuit configured to select at least one of the DC source and the host of batteries in response to a PMU output signal from the PMU.

Advantages of the present invention will be apparent from the following detailed description of exemplary embodiments thereof, which description should be considered in conjunction with the accompanying drawings, in which:

FIG. 1 is a simplified high level block diagram of an electronic device with a power supply block having a selector circuit consistent with the invention that makes a selection in response to an output signal from a power management unit (PMU);

FIG. 2 is a more detailed block diagram of the power supply block portion of FIG. 1 having a selector circuit consistent with the invention for making a selection among a DC power source and a plurality of batteries;

FIG. 3 is a block diagram of one exemplary embodiment of a selector circuit consistent with the invention having a controller configured to provide signals to select among a DC power source and a plurality of batteries via an associated switch driver network and associated switches;

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