Charger system with dual-level current regulation and dual-level thermal regulation

• US 6,861,824 B1
• Filed: 07/10/2002
• Issued: 03/01/2005
• Est. Priority Date: 07/10/2002
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: California Micro Devices Corporation (ON Semiconductor Corporation)
• Inventors: Shih, Fu-Yuan, Negru, Sorin L., Liu, Kwang H.
• Primary Examiner(s): Tso, Edward H.
• Application Number:
  US10/193,381
• Time in Patent Office: 965 Days
• Field of Search: 320/164, 320/137, 320/160, 320/161, 320/162, 320/163, 320/140
• US Class Current: 320/164
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence

Abstract

A charging system that concurrently charges a main system and a battery for powering the main system when the charging system is connected to an adapter. The charging system includes a current sensing resistor, a first current control circuit for regulating the current in a linear battery charger and a second current control circuit for controlling the maximum adapter current. The charging system further includes a first temperature control circuit for regulating the current in the battery charger and a second temperature control circuit for controlling the maximum power dissipation of the charging system. The charging system further includes a linear regulator for providing power to the main system from the adapter and a main system voltage control circuit and a battery voltage control circuit. The charging system apportions the adapter current between the main system and the battery charger giving priority to the main system.

Claims

1. A charger system for providing power to a main system and a battery, the charger system comprising:

a current sensing circuit that includes a current sensing resistor for developing a voltage drop signal proportional to the current passing through the resistor, and an amplifier connected to the resistor for boosting the voltage drop signal across the resistor;

a linear charger connected to receive current from an external adapter via the current sensing resistor and to provide, on an output, current to the battery, the linear charger having a first control input that controls the quantity of current provided by the linear charger to the battery,

a linear regulator connected to receive current from an external adapter via the current sensing resistor and to provide, on an output, current to the main system, the linear regulator having a second control input that controls the quantity of current provided by the linear regulator to the main system;

a shutdown circuit for preventing the operation of the linear regulator and the linear charger upon receipt of a first or second shutdown input;

a first current control circuit connected to the amplifier output of the current sensing circuit, the first current control circuit having an output connected to the first shutdown input and an input for receiving a first preset voltage that determines a signal value on the first shutdown input;

a second current control circuit connected to the amplifier output of the current sensing circuit, the second current control circuit having an output connected to the first control input and an input for connecting to a second preset voltage that determines a signal value on the first control input;

a temperature sensor for sensing the operating temperature of at least the linear regulator and the linear charger and providing an output indicative of the sensed temperature;

a first temperature control circuit having an input connected to receive the temperature sensor output and an input for receiving a voltage indicative of a first preset temperature, the first temperature control circuit having an output connected to the first control input to control the current passing through the linear charger, and the first temperature control circuit throttling down the linear charger when the sensed temperature exceeds the first preset temperature;

a second temperature control circuit having an input connected to receive the temperature sensor output and an input for receiving a voltage indicative of a second preset temperature, the second temperature control circuit having an output connected to the second shutdown input to shut down the linear regulator and linear charger when the sensed temperature equals or exceeds the second preset temperature,

a first voltage control circuit having a first input connected to the output of the linear regulator and second input for connecting to a third preset voltage, the first voltage control circuit having an output connected to the control input of the linear regulator to regulate the voltage provided to the main system; and

a second voltage control circuit having a first input connected to the output of the linear charger and a second input for connecting to a fourth preset voltage, the second voltage control circuit having an output connected to the control input of the linear charger to regulate the voltage provided to the battery.

2. A charger system for providing power to a main system and a battery, the charger system comprising:

means for sensing current provided by an external adapter;

means for sensing temperature of charger system;

main system regulator means for providing a current and voltage to the main system and for regulating said main system current and voltage;

battery charger means for providing a current and voltage to the battery and for regulating said battery current and voltage;

means, connected to the battery charger means, for limiting the maximum current provided by the battery charger means in response to the sensing current means;

means, connected to the battery charger means, for limiting the maximum current provided by the battery charger means in response to temperature sensing means;

throttling means for throttling down the charger system in response to either the sensing current means or the sensing temperature means;

means, connected to the throttling means, for limiting the maximum current provided by the external adapter in response to the sensing current means;

means, connected to the main system regulator means, for controlling the voltage provided by the main system regulator means; and

means, connected to the battery charger means, for controlling the voltage provided by the battery charger means.

3. A charger system for providing power to a main system and a battery, the charger system comprising:

a current sensing resistor for developing a voltage drop based on the current supplied from an external adapter;

a linear regulator having an input connected to receive current from the external adapter via the current sensing resistor, an output for supplying current to the main system, and a control input for controlling the amount of current supplied by the output to the main system;

a linear charger having an input connected to receive current from the external adapter via the current sensing resistor, an output for supplying current to the battery, an a control input for controlling the amount of current supplied by the output to the battery;

a shut down circuit having a pair of inputs, a signal on either input instructing the shut down circuit to at least shut down the linear regulator and the linear charger;

three diodes each having a negative terminal connected to the control input of the linear charger;

a temperature sensor for sensing an operating temperature of at least the linear regulator and linear charger, and for providing on an output a voltage indicative of sensed operating temperature;

a first amplifier connected differentially to the current sensing resistor, the first amplifier having an output for carrying an amplified voltage drop across the current sensing resistor;

a first comparator having a first input connected to the output of the first amplifier and a second input connected to a first preset voltage, the first comparator having an output connected to one of the inputs of the shut down circuit;

a second amplifier having a first input connected to the output of the first amplifier and a second input connected to a second preset voltage, the second amplifier having an output connected to a positive terminal of a first one of the three diodes;

a third amplifier having a first input connected to the output of the linear regulator and a second input connected to a third preset voltage, the third amplifier having an output connected to the control input of the linear regulator;

a fourth amplifier having a first input connected to the output of the linear charger and a second input connected to a fourth preset voltage, the fourth amplifier having an output connected to a positive terminal of a second one of the three diodes;

a fifth amplifier having a first input connected to the output of the temperature sensor and a second input connected to a voltage indicative of a first preset temperature, the fifth amplifier having an output connected to a positive terminal of a third one of the three diodes;

a second comparator having a first input connected to the output of the temperature sensor and a second input connected to a voltage indicative of a second preset temperature, the second comparator having an output connected to the other input of the shutdown circuit.

4. A charger system as recited in claim 3,

wherein the current sensing resistor, the linear regulator, the linear charger, the shutdown circuit, the three diodes, the temperature sensor, the first through fifth amplifiers and the first and second comparators all reside on a common substrate;

and

wherein the temperature sensor senses the temperature of the common substrate.

5. A charger system as recited in claim 3, wherein the first preset voltage is greater than the second preset voltage.

6. A charger system as recited in claim 5, wherein the first preset voltage is 1.0 Volt.

7. A charger system as recited in claim 5, wherein the second preset voltage is 0.95 Volt.

8. A charger system as recited in claim 3, wherein the third preset voltage is equal to the fourth preset voltage.

9. A charger system as recited in claim 8, wherein the fourth preset voltage is 4.2 Volts.

10. A charger system as recited in claim 8, wherein the fourth preset voltage is approximately the voltage of the battery when fully charged.

11. A charger system as recited in claim 3, wherein the second preset temperature is greater than the first preset temperature.

12. A charger system as recited in claim 11, wherein the first preset temperature is approximately 105 degrees C.

13. A charger system as recited in claim 11, wherein the first preset temperature is the maximum operating temperature of the linear regulator.

14. A charger system as recited in claim 11, wherein the first preset temperature is the maximum operating temperature of the linear charger.

15. A charger system as recited in claim 11, wherein the second preset temperature is approximately 150 degrees C.