POWER ADAPTER

• US 20140043862A1
• Filed: 08/08/2012
• Published: 02/13/2014
• Est. Priority Date: 08/08/2012
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Luh, Louis, Smith, Eric G.
• Granted Patent: US 9,590,519 B2
• Time in Patent Office: Days
• US Class Current: 363/17
• 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 1/4208 Arrangements for improving power factor of AC input
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators
• CPC Class Codes: H02M 3/335 using semiconductor devices only
• CPC Class Codes: H02M 3/33571 Half-bridge at primary side of an isolation transformer
• CPC Class Codes: H02M 3/33573 Full-bridge at primary side of an isolation transformer
• CPC Class Codes: H02M 7/10 arranged for operation in series, e.g. for multiplication of voltage
• CPC Class Codes: H02M 7/2176 comprising a passive stage to generate a rectified sinusoidal voltage and a controlled switching element in series between such stage and the output
• CPC Class Codes: H02M 7/53871 with automatic control of output voltage or current
• 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

Embodiments of an adapter are disclosed that include a rectifier with an input and an output coupled to a step-down transformer with a primary coil and a secondary coil, wherein the primary coil is coupled to the output of the rectifier. A step-up converter is coupled to the secondary coil.

Claims

1. An adapter, comprising:

a rectifier with an input and an output;

a step-down transformer with a primary coil and a secondary coil, wherein the primary coil is coupled to the output of the rectifier; and

a step-up converter coupled to the secondary coil.

2. The adapter of claim 1, further including:

a first diode with a first anode and a first cathode; and

a second diode with a second anode and a second cathode, wherein the secondary coil includes a center tap coupled to a ground, a first end tap coupled to the first anode, a second end tap coupled to the second anode, and wherein the first cathode is coupled to the second cathode and to the step-up converter.

3. The adapter of claim 2, further including:

an H-bridge, with an input and an output, wherein the H-bridge input is coupled to the rectifier output and the H-bridge output is coupled to the primary coil.

4. The adapter of claim 2, wherein a turns ratio of the primary coil to the secondary coil is in the range from 4:

1 to 8;

1.

5. The adapter of claim 2, further including:

a capacitor coupled to a first end of the primary coil; and

a half H-bridge, with an input and an output, wherein the half H-bridge input is coupled to the rectifier output and the half H-bridge output is coupled to a second end of the primary coil.

6. The adapter of claim 2, further including:

a controller coupled to the step-up converter, wherein the controller is configured to control the step-up converter to step-up a voltage from the secondary coil based on an output voltage of the rectifier and a power demand from the adapter.

7. The adapter of claim 1, further including:

a capacitor coupled to an output of the step-up converter, wherein a maximum voltage rating of the capacitor is less than or equal to a maximum input voltage rating of the adapter.

8. The adapter of claim 1, further including:

a capacitor coupled to an output of the step-up converter, wherein a maximum voltage rating of the capacitor is less than or equal to 50 volts.

9. An adapter, comprising:

a step-down transformer with a primary coil and a secondary coil, wherein the secondary coil includes a center tap coupled to a ground, and a first end tap and a second end tap;

a first diode with a first anode and a first cathode, wherein the first anode is coupled to the first end tap;

a second diode with a second anode and a second cathode, wherein the second anode is coupled to the second end tap, and the first cathode is coupled to the second cathode; and

a step-up converter coupled to the first cathode and the second cathode.

10. The adapter of claim 9, further including:

a controller coupled to the step-up converter, wherein the controller is configured to control the step-up converter to step-up a voltage from the secondary coil based on a power demand from the adapter.

11. The adapter of claim 9, wherein a turns ratio of the primary coil to the secondary coil is in the range from 4:

1 to 8;

1.

12. The adapter of claim 9, further including:

a rectifier with an input and an output; and

an H-bridge with an input and an output, wherein the output of the rectifier is coupled to the input of the H-bridge and the output of the H-bridge is coupled to the primary coil.

13. The adapter of claim 9, further including:

a rectifier with an input and an output;

a capacitor coupled to a first end of the primary coil; and

a half H-bridge with an input and an output, wherein the output of the rectifier is coupled to the input of the half H-bridge and the output of the half H-bridge is coupled to a second end of the primary coil.

14. The adapter of claim 9, further including:

a capacitor coupled to an output of the step-up converter, wherein a maximum voltage rating of the capacitor is less than or equal to a maximum input voltage rating of the adapter.

15. The adapter of claim 9, further including:

a capacitor coupled to an output of the step-up converter, wherein a maximum voltage rating of the capacitor is less than 50 volts.

16. A method for generating an output voltage in an adapter, comprising:

receiving an alternating current voltage;

rectifying the alternating current voltage;

applying the rectified voltage across a primary coil in a step-down transformer; and

stepping-up the voltage from a secondary coil of the step-down transformer.

17. The method of claim 16, wherein stepping-up the voltage includes stepping-up the voltage to a value less than or equal to 50 volts.

18. The method of claim 16, wherein a maximum voltage in the adapter is less than or equal to the alternating current voltage.

19. The method of claim 16, wherein stepping-up the voltage includes stepping-up the voltage based on a power demand from the adapter.

20. The method of claim 16, wherein applying the voltage across the primary coil includes switching a polarity of the voltage across the primary coil at a frequency of at least 50,000 Hz, and wherein a switching frequency of the step-up converter is at least 50,000 Hz.