Led driver circuit and led driving method

Patent metadata

Field	Value
Publication number	US-2019297694-A1
Application number	US-201916436484-A
Country	US
Kind code	A1
Filing date	Jun 10, 2019
Priority date	Jul 7, 2016
Publication date	Sep 26, 2019
Grant date	—

Abstract

A light emitting diode (LED) driver circuit includes an LED string and a conducting state detection circuit. The conducting state detection circuit detects a conducting state of the LED string, and generates a discharge control signal upon sensing that the LED string is in a non-conducting state. A current source generates a discharge current according to the discharge control signal when the LED string is in the non-conducting state. A passive bleeder provides current compensation by internal regulator operation. An LED spike current suppression circuit suppresses spike current that can occur when the input voltage increases above a threshold. A bias supply circuit has an input capacitor that provides a bias voltage.

First claim

What is claimed is:

1 . A light emitting diode (LED) driver circuit, comprising:
an LED string having a first end that is connected to an input voltage, the LED string comprising at least one LED element; at least one channel connected to the at least one LED element; a sense resistor having a first end that is connected to the at least one channel and a second end that is connected to ground; at least one regulator connected between the at least one channel and the first end of the sense resistor and configured to control current flowing through the at least one channel based on a control voltage; and a passive bleeder connected between the input voltage and the first end of the sense resistor.

2 . The LED driver circuit of claim 1 , wherein the at least one regulator comprises:
a transistor connected between the at least one channel and the first end of the sense resistor; and an amplifier comprising a first input connected to the control voltage, a second input connected to the first end of the sense resistor, and an output connected to a gate of the transistor.

3 . The LED driver circuit of claim 1 , wherein the passive bleeder comprises a resistor and a capacitor connected in series between the input voltage and the first end of the sense resistor.

4 . A light emitting diode (LED) driver circuit, comprising:
an LED string having a first end that is connected to an input voltage, the LED string comprising at least one LED element; at least one channel connected to the at least one LED element; a sense resistor having a first end that is connected to the at least one channel; at least one regulator connected between the at least one channel and the first end of the sense resistor and configured to control current flowing through the at least one channel based on a control voltage; and a spike current suppression circuit that is configured to pull down an output of an amplifier of the at least one regulator when the input voltage is below a threshold voltage.

5 . The LED driver circuit of claim 4 , wherein the at least one regulator comprises:
a transistor connected between the at least one channel and the first end of the sense resistor; and the amplifier comprising a first input connected to the control voltage, a second input connected to the first end of the sense resistor, and the output connected to a gate of the transistor.

6 . The LED driver circuit of claim 5 , wherein the spike current suppression circuit comprises:
another transistor having a drain connected to the output of the amplifier, a source that is connected to ground, and a gate that is connected to receive an input threshold voltage that is indicative of a level of the input voltage.

7 . A light emitting diode (LED) driver circuit, comprising:
an LED string having a first end that is connected to an input voltage, the LED string comprising at least one LED element; at least one channel connected to the at least one LED element; an LED current controller that is configured to regulate current through the at least one channel; and a bias supply circuit that is configured to provide a bias voltage to the LED current controller, the bias supply circuit comprising a capacitor, a first diode, and a second diode, wherein a first end of the capacitor is connected to the input voltage, a second end of the capacitor is connected to an anode of the first diode, a cathode of the second diode is connected to the second end of the capacitor, and a cathode of the first diode provides the bias voltage.

8 . The LED driver circuit of claim 7 , wherein the anode of the second diode is connected to ground.

9 . The LED driver circuit of claim 7 , wherein the second diode is a Zener diode.

10 . The LED driver circuit of claim 7 , further comprising a resistor that is in series with the capacitor.

11 . The LED driver circuit of claim 7 , further comprising a dimmer that is configured to modulate the input voltage.

12 . The LED driver circuit of claim 7 , wherein the LED current controller comprises at least one regulator, the at least one regulator comprising:
a transistor connected between the at least one channel and a sense resistor; and an amplifier comprising a first input connected to a control voltage, a second input connected to the sense resistor, and an output connected to a gate of the transistor.

Assignees

• Semiconductor Components Ind Llc

Inventors

• Kim Young-Jong
• Eum Hyun-Chul

Classifications

• H05B45/3575

  by means of dummy loads or bleeder circuits, e.g. for dimmers · CPC title

• H05B45/48

  having LEDs organised in strings and incorporating parallel shunting devices · CPC title

• H05B45/50

  responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits · CPC title

• H05B33/0845

  Electricity · mapped topic

• H05B33/0812 Primary

  Electricity · mapped topic