# US 9,521,715 B2 · Current shaping for dimmable LED

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- Number: US 9,521,715 B2
- Document ID: US9521715B2
- Status: Granted
- Kind: B2
- Application number: 14/285,058
- Filed: 2014-05-22
- Published: 2014-11-27
- Granted: 2016-12-13
- Earliest claimed: 2013-05-24
- Assignees: Marvell World Trade Ltd.
- Applicants: Marvell World Trade Ltd
- Inventors: Sehat Sutardja; Pantas Sutardja; Wanfeng Zhang
- Web page: https://patentgrep.com/patent/US9521715B2

## CPC

- H02M 1/4258: {using a single converter stage both for correction of AC input power factor and generation of a regulated and galvanically isolated DC output voltage (H02M1/4241 takes precedence)}
- H02M 3/335: using semiconductor devices only
- H02M 3/33507: {with automatic control of the output voltage or current, e.g. flyback converters (H02M3/33561, H02M3/33569 take precedence)}
- H02M 7/219: in a bridge configuration
- H05B 45/10: Controlling the intensity of the light
- H05B 45/3725: Switched mode power supply [SMPS]
- H05B 45/385: using flyback topology
- 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
- H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P)
- H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS

## Abstract

Aspects of the disclosure provide a circuit that includes a detector and a controller. The detector is configured to detect a firing start by a triode for alternating current (TRIAC) in a power supply. The controller is configured to control a switch in connection with a magnetic component in response to the firing start to shape a profile of a current pulled from the power supply to satisfy a latch current requirement and a hold current requirement of the TRIAC.

## Claims

### Claim 1

A circuit, comprising:
a detector configured to detect a start of turning on a triode for alternating current (TRIAC) in a power supply; and
a controller configured to control a switch in connection with a magnetic component in response to the start of turning on the TRIAC in the power supply to adjust a switching current flowing through the magnetic component to have at least a first peak current and a second peak current, the adjustment of the switching current flowing through the magnetic component causing a current pulled from the power supply to satisfy a latch current requirement when the switching current is adjusted to have the first peak current and to satisfy a hold current requirement of the TRIAC when the switching current is adjusted to have the second peak current.

### Claim 2 (depends on 1)

The circuit of claim 1, wherein the controller is configured to adjust the switching current to cause the current at a first level to enable enough latch current for the TRIAC at the start of turning on the TRIAC in the power supply.

### Claim 3 (depends on 1)

The circuit of claim 1, wherein the detector is configured to detect the switching current passing through the switch, and the controller is configured to control the switch according to the detected switching current to shape the current pulled from the power supply.

### Claim 4 (depends on 2)

The circuit of claim 2, wherein the controller is configured to adjust the switching current to cause the current at a second level that is lower than the first level to enable enough hold current for the TRIAC after the start of turning on the TRIAC in the power supply.

### Claim 5 (depends on 3)

The circuit of claim 3, wherein the current pulled from the power supply includes the switching current, and a damping current by a damping circuit.

### Claim 6 (depends on 3)

The circuit of claim 3, wherein the controller is configured to control at least one of a rising edge delay for the current to rise to the first level, a rising edge slope for the current to rise to the first level, a duration for the current to above a threshold, and a falling edge slope for the current to fall from the first level to the second level.

### Claim 7 (depends on 5)

The circuit of claim 5, wherein a capacitance of the damping circuit is smaller than a specific value.

### Claim 8

An apparatus, comprising:
a switch in connection with a magnetic component for transferring energy from an energy source to a load; and
an integrated circuit (IC) chip comprising:
a detector configured to detect a start of turning on a triode for alternating current (TRIAC) in the energy source; and
a controller configured to control the switch in response to the start of turning on the TRIAC in the energy source to adjust a switching current flowing through the magnetic component to have at least a first peak current and a second peak current, the adjustment of the switching current flowing through the magnetic component causing a current pulled from the energy source to satisfy a latch current requirement when the switching current is adjusted to have the first peak current and to satisfy a hold current requirement of the TRIAC when the switching current is adjusted to have the second peak current.

### Claim 9 (depends on 8)

The apparatus of claim 8, wherein the controller is configured to adjust the switching current to cause the current at a first level to enable enough latch current for the TRIAC at the start of turning on the TRIAC in the energy source.

### Claim 10 (depends on 8)

The apparatus of claim 8, wherein the detector is configured to detect the switching current passing through the switch, and the controller is configured to control the switch according to the detected switching current to shape the current pulled from the power supply.

### Claim 11 (depends on 8)

The apparatus of claim 8, further comprising:
a damping circuit configured to pull a damping current in response to the start of turning on the TRIAC in the energy source, and the current pulled from the energy source including the switching current, and the damping current.

### Claim 12 (depends on 8)

The apparatus of claim 8, wherein the apparatus does not include a damping circuit, and the controller is configured to control the switch in response to the start of turning on the TRIAC in the energy source to shape the switching current to satisfy operation requirements of the TRIAC.

### Claim 13 (depends on 9)

The apparatus of claim 9, wherein the controller is configured to adjust the switching current to cause the current at a second level that is lower than the first level to enable enough hold current for the TRIAC after the start of turning on the TRIAC in the energy source.

### Claim 14 (depends on 10)

The apparatus of claim 10, wherein the controller is configured to control at least one of a rising edge delay for the current to rise to the first level, a rising edge slope for the current to rise to the first level, a duration for the current to above a threshold, and a falling edge slope for the current to fall from the first level to the second level.

### Claim 15

A method, comprising:
detecting a start of turning on a triode for alternating current (TRIAC) in a power supply; and
switching on/off a switch in connection with a magnetic component in response to the start of turning on the TRIAC in the power supply to adjust a switching current flowing through the magnetic component to have at least a first peak current and a second peak current, the adjustment of the switching current flowing through the magnetic component causing a current pulled from the power supply to satisfy a latch current requirement when the switching current is adjusted to have the first peak current and to satisfy a hold current requirement of the TRIAC when the switching current is adjusted to have the second peak current.

### Claim 16 (depends on 15)

The method of claim 15, wherein switching on/off the switch in connection with the magnetic component in response to the start of turning on the TRIAC in the power supply to adjust the switching current flowing through the magnetic component further comprises:
switching on/off the switch to pull the current at a first level to enable enough latch current for the TRIAC at the start of turning on the TRIAC in the power supply.

### Claim 17 (depends on 15)

The method of claim 15, wherein switching on/off the switch in connection with the magnetic component in response to the start of turning on the TRIAC in the power supply to adjust the switching current flowing through the magnetic component further comprises:
switching on/off the switch to pull the current at a second level that is lower than the first level to enable enough hold current for the TRIAC after the start of turning on the TRIAC in the power supply.

### Claim 18 (depends on 17)

The method of claim 17, further comprising:
switching on/off the switch to control at least one of a rising edge delay for the current to rise to the first level, a rising edge slope for the current to rise to the first level, a duration for the current to above a threshold, and a falling edge slope for the current to fall from the first level to the second level.

### Claim 19 (depends on 15)

The method of claim 15, further comprising:
detecting the switching current passing through the switch; and
switching on/off the switch according to the detected switching current to shape the current pulled from the power supply.

### Claim 20 (depends on 15)

The method of claim 15, further comprising:
flowing a damping current by a damping circuit in response to the start of turning on the TRIAC in the power supply to satisfy a latch current requirement for the TRIAC.