Monolithic battery charging device

• US 6,791,298 B2
• Filed: 11/05/2002
• Issued: 09/14/2004
• Est. Priority Date: 11/05/2001
• Status: Expired due to Fees

• Current Assignee: Unifi Scientific Batteries LLC (Innovation Management Sciences, LLC)
• Original Assignee: Shakti Systems Inc.
• Inventors: Shenai, Krishna, Abedinpour, Siamak
• Primary Examiner(s): Tso, Edward H.
• Application Number:
  US10/288,177
• Publication Number:
  US 20030090237A1
• Time in Patent Office: 679 Days
• Field of Search: 320/123, 320/128, 320/134, 320/136, 320/137, 320/140, 323/351, 323/282, 323/284
• US Class Current: 320/128
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02J 2207/40 adapted for charging from various sources, e.g. AC, DC or multivoltage
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 3/1588 comprising at least one synchronous rectifier element H02M3/1582, H02M3/1584 take precedence
• CPC Class Codes: Y02B 40/00 Technologies aiming at improving the efficiency of home appliances, e.g. induction cooking or efficient technologies for refrigerators, freezers or dish washers
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A monolithically formed battery charger may be fabricated as an integral part of a multifunctional integrated circuit or as independent monolithically formed integrated circuit. The monolithically formed battery charger includes at least one step-down converter having a given duty ratio coupled to a battery-terminal interface that provides a stepped-down output voltage and current that may be used to charge a rechargeable battery.

The step-down converter includes one or more cascaded monolithically-formed synchronous-buck regulators operating at a frequency of at least one megahertz. Each regulator may include a capacitor, inductor, controller, switch, and rectifier. When cascaded, the high-side output node of a preceding synchronous-buck regulator is connected to the switch in a successive synchronous-buck regulator.

Claims

1. A monolithic battery charger comprising:

a step-down converter having a duty ratio in the range of approximately 10 to approximately 95 and comprising at least one monolithically formed buck-type regulator coupled to a capacitor and an inductor, wherein at least one monolithically formed buck-type regulator comprises a switching controller, a switch, and a rectifier in a standard buck configuration, and wherein the controller operates at a switching frequency of at least 1 megahertz; and

a battery-terminal interface connected to the step-down converter for providing an output current and an output voltage to a rechargeable battery.

2. The monolithic battery charger of claim 1 wherein said at least one monolithically formed buck type regulator comprises a plurality of serially connected monolithically formed buck-type regulators, wherein each controller operates at a switching frequency of at least one megahertz, and each of which has a duty ratio of between 10 and 95.

3. The monolithic battery charger of claim 2, wherein a cumulative duty ratio comprises the multiplicative combination of the duty ratio for each of the plurality the monolithically formed buck-type regulators.

4. The monolithic battery charger of claim 1, wherein the switch comprises a synchronous switch.

5. The monolithic battery charger of claim 4, wherein the synchronous switch comprises a P-type Metal Oxide Semiconductor switch.

6. The monolithic battery charger of claim 5, wherein the P-type Metal Oxide Semiconductor switch comprises at plurality of P-type Metal Oxide Semiconductor Field Effect Transistor.

7. The monolithic battery charger of claim 1, wherein the rectifier is operable at a frequency of at least one megahertz.

8. The battery charging device of claim 7, wherein the rectifier comprises a synchronous rectifier.

9. The battery charger of claim 8, wherein the synchronous rectifier comprises an N-type Metal Oxide Semiconductor synchronous rectifier.

10. The monolithic battery charger of claim 1, wherein the rectifier comprises a synchronous rectifier, wherein the switch comprises a synchronous switch, wherein the switching controller asynchronously provides a first trigger to the synchronous switch and a second trigger to the synchronous rectifier in synchrony, wherein when the first trigger causes the synchronous switch to cycle from an on state to an off state, the second trigger causes the synchronous rectifier to cycle from an off state to an on state, and wherein when the first trigger causes the synchronous switch to cycle from the off state to the on state, the second trigger causes the synchronous rectifier to cycle from the on state to the off state.

11. The monolithic battery charger of claim 10, wherein the switching controller comprises a single gate driver.

12. The monolithic battery charger of claim 10, wherein the switching controller comprises a single gate driver and a buffer driver.

13. The monolithic battery charger of claim 10, further comprising a current-sensing feedback controller.

14. The monolithic battery charger of claim 10, further comprising a voltage-sensing feedback controller.

15. The monolithic battery charger of claim 1, wherein the switching controller comprises a single gate driver.

16. The monolithic battery charger of claim 1, wherein the switching controller comprises a single gate driver and a buffer driver.

17. The monolithic battery charger of claim 1, further comprising a current-sensing feedback controller.

18. The monolithic battery charger of claim 1, further comprising a voltage-sensing feedback controller.

19. A monolithic battery charger comprising, in combination:

a first monolithically formed buck type regulator comprising;

a first P-type Metal Oxide Semiconductor switch having a first terminal for coupling to a high-side terminal of an external power supply,

a first synchronous N-type Metal Oxide Semiconductor rectifier having a first terminal coupled in series with a second terminal of the first P-type Metal Oxide Semiconductor switch at a first node,

a first inductor having a first terminal coupled in series with the second terminal of the first P-type Metal Oxide Semiconductor switch at the first node,

a first capacitor having a first terminal coupled to the second terminal of the first monolithically-formed inductor at a first-output node and having a second terminal for coupling to a low-side terminal of the external power supply at a ground node; and

a first control circuit having (i) at least one input for receiving at least one feedback signal that is based on output signals detected at the first-output node, (ii) logic for generating switching signals to control the P-type Metal Oxide Semiconductor switch in response to the at least one feedback signal, and (iii) an output for triggering the first P-type Metal Oxide Semiconductor switch in response to the switching signals; and

a second monolithically formed buck type regulator coupled in series with the first monolithically formed buck type regulator, the second monolithically formed buck type regulator comprising;

a second P-type Metal Oxide Semiconductor switch having a first terminal coupled to the first-output node of the first monolithically formed buck type regulator,

a second synchronous N-type Metal Oxide Semiconductor rectifier having a first terminal coupled in series with a second terminal of the second P-type Metal Oxide Semiconductor switch at a second node,

a second inductor having a first terminal coupled in series with the second terminal of the second P-type Metal Oxide Semiconductor switch at the second node,

a second capacitor having a first terminal coupled to the second terminal of the second monolithically-formed inductor at a second-output node and having a second terminal coupled to the ground node; and

a second control circuit having (i) at least one input for receiving at least one feedback signal that is based on output signals detected at the second-output node, (ii) logic for generating switching signals to control the P-type Metal Oxide Semiconductor switch in response to the at least one feedback signal, and (iii) an output for triggering the second P-type Metal Oxide Semiconductor switch in response to the switching signals; and

a battery-terminal interface coupled to the second-output node and the ground node, wherein the battery-terminal interface provides an output current and an output voltage to a rechargeable battery, wherein first control circuit and the second control circuit a control circuit r operate at a switching frequency of at least 150 megahertz.

20. The monolithic battery charger of claim 19, wherein the first control circuit further includes logic for generating switching signals to control the first-N-type Metal Oxide Semiconductor rectifier in response to the at least one feedback signal, and a second output for triggering the first N-type Metal Oxide Semiconductor switch in response to the switching signals.

21. The monolithic battery charger of claim 20, wherein the second control circuit further includes logic for generating switching signals to control the second-N-type Metal Oxide Semiconductor rectifier in response to the at least one feedback signal, and a second output for triggering the second-N-type Metal Oxide Semiconductor switch in response to the switching signals.

22. The monolithic battery charger of claim 20, wherein the first control circuit further includes a single gate driver and a buffer driver.

23. The monolithic battery charger of claim 19, wherein the first control circuit further includes a current-sensing feedback controller.

24. The monolithic battery charger of claim 19, wherein the first control circuit further includes a voltage-sensing feedback controller.

25. The monolithic battery charger of claim 19, wherein the second control circuit further includes logic for generating switching signals to control the second-N-type Metal Oxide Semiconductor rectifier in response to the at least one feedback signal, and a second output for triggering the second-N-type Metal Oxide Semiconductor switch in response to the switching signals.

26. The monolithic battery charger of claim 25, wherein the second control circuit further includes a single gate driver and a buffer driver.

27. The monolithic battery charger of claim 19, wherein the second control circuit further includes a current-sensing feedback controller.

28. The monolithic battery charger of claim 19, wherein the second control circuit further includes a voltage-sensing feedback controller.

29. The monolithic battery charger of claim 19, wherein the first and second monolithically formed buck type regulators are formed on a single substrate.