Driving device and driving method for light- emitting element

1 . A driving device for a light-emitting element, comprising:

a driving circuit, adapted to output a driving signal to drive a light-emitting element circuit, wherein the driving circuit is enabled or disabled based on an enabling signal, and the driving circuit dynamically adjusts a duty cycle of the driving signal based on a relationship between a dimming voltage and current information of the light-emitting element circuit;

a softstart circuit, having an output terminal coupled to the driving circuit to provide the dimming voltage, wherein the softstart circuit pulls down an original adjustment voltage to generate a pulled-down voltage as the dimming voltage in response to the enabling signal disabling the driving circuit, and the softstart circuit pulls up the dimming voltage in response to the enabling signal enabling the driving circuit; and

a first capacitor, coupled to the output terminal of the softstart circuit,

wherein the softstart circuit comprises:

a first resistor, having a first terminal adapted to receive the original adjustment voltage, wherein a second terminal of the first resistor is coupled to the output terminal of the softstart circuit; and

a variable resistor circuit, coupled between the second terminal of the first resistor and a first reference voltage, wherein the variable resistor circuit reduces a resistance of the variable resistor circuit in response to the enabling signal disabling the driving circuit, and the variable resistor circuit increases the resistance of the variable resistor circuit in response to the enabling signal enabling the driving circuit.

2 . The driving device according to claim 1 , wherein the variable resistor circuit comprises:

a second resistor, having a first terminal coupled to the second terminal of the first resistor, wherein a second terminal of the second resistor is coupled to the first reference voltage; and

a shunt circuit, coupled to the second terminal of the first resistor, wherein the shunt circuit provides a shunt path to the second terminal of the first resistor in response to the enabling signal disabling the driving circuit, and the shunt circuit turns off the shunt path in response to the enabling signal enabling the driving circuit.

3 . The driving device according to claim 2 , wherein the shunt circuit comprises:

a third resistor, having a first terminal coupled to the second terminal of the first resistor; and

a switch circuit, coupled between a second terminal of the third resistor and the first reference voltage, wherein the switch circuit is turned on in response to the enabling signal disabling the driving circuit, and the switch circuit is turned off in response to the enabling signal enabling the driving circuit.

4 . The driving device according to claim 3 , wherein the switch circuit comprises:

a first switch, having a first terminal coupled to the second terminal of the third resistor, wherein a second terminal of the first switch is coupled to the first reference voltage; and

a control circuit, coupled to a control terminal of the first switch, wherein the control circuit turns on the first switch in response to the enabling signal disabling the driving circuit, and the control circuit turns off the first switch in response to the enabling signal enabling the driving circuit.

5 . The driving device according to claim 4 , wherein the control circuit comprises:

a fourth resistor, having a first terminal coupled to a power supply voltage, wherein a second terminal of the fourth resistor is coupled to the control terminal of the first switch; and

a second switch, having a first terminal coupled to the control terminal of the first switch, wherein a second terminal of the second switch is coupled to a second reference voltage, the second switch is turned off in response to the enabling signal disabling the driving circuit, and the second switch is turned on in response to the enabling signal enabling the driving circuit.

6 . The driving device according to claim 5 , wherein the control circuit further comprises:

a fifth resistor, having a first terminal coupled to the second terminal of the fourth resistor, wherein a second terminal of the fifth resistor is coupled to a third reference voltage;

a sixth resistor, having a first terminal adapted to receive the enabling signal, wherein a second terminal of the sixth resistor is coupled to a control terminal of the second switch; and

a seventh resistor, having a first terminal coupled to the second terminal of the sixth resistor, wherein a second terminal of the seventh resistor is coupled to a fourth reference voltage.

7 . A driving method for a light-emitting element, comprising:

enabling or disabling a driving circuit by an enabling signal;

dynamically adjusting a duty cycle of a driving signal by the driving circuit based on a relationship between a dimming voltage and current information of a light-emitting element circuit, wherein an output terminal of a softstart circuit is coupled to the driving circuit to provide the dimming voltage;

outputting the driving signal by the driving circuit to drive the light-emitting element circuit;

pulling down an original adjustment voltage to generate a pulled-down voltage as the dimming voltage by the softstart circuit in response to the enabling signal disabling the driving circuit;

pulling up the dimming voltage by the softstart circuit in response to the enabling signal enabling the driving circuit, wherein a first capacitor is coupled to the output terminal of the softstart circuit;

reducing a resistance of a variable resistor circuit by the variable resistor circuit of the softstart circuit in response to the enabling signal disabling the driving circuit, wherein a first terminal of a first resistor of the softstart circuit receives the original adjustment voltage, a second terminal of the first resistor is coupled to the driving circuit to provide the dimming voltage, and the variable resistor circuit is coupled between the second terminal of the first resistor and a reference voltage; and

increasing the resistance of the variable resistor circuit by the variable resistor circuit in response to the enabling signal enabling the driving circuit.