US 11,057,976 B2 · Short to ground and open protecting circuit, and associated protecting method

Abstract

A short to ground protecting circuit for an LED driver for providing a power supply voltage for N LED strings. The LED driver has an output terminal for providing a power supply voltage for the N LED strings and N feedback terminals having N detecting voltages respectively. For each i from 1 to N, the ith LED string is coupled between the output terminal and the ith feedback terminal, and the ith feedback terminal is configured to have the ith detecting voltage. The short to ground protecting circuit receives a short threshold voltage and N open fault signals, and generates N short indicating signals. And on the premise of the ith open fault signal is valid, and if the ith detecting voltage is less than the short threshold voltage for a preset time period, the ith short indicating signal is valid.

Claims20

Dependent claims

A short to ground protecting circuit used in a light emitting diode (LED) driver for powering N LED strings, wherein the short to ground protecting circuit comprises a charging switch module having N input terminals to receive N open fault signals respectively, and a short comparing module configured to provide N short indicating signals, wherein N is an integer greater than or equal to 1, the LED driver has an output terminal for providing a power supply voltage for the N LED strings and N feedback terminals having N detecting voltages respectively, wherein i is an integer in a range from 1 to N, for each i from 1 to N, the ith LED string of the N LED strings is coupled between the output terminal and the ith feedback terminal of the N feedback terminals, and the ith feedback terminal is configured to have the ith detecting voltage of the N detecting voltages, wherein the short to ground protecting circuit is configured to receive a short threshold voltage and the N open fault signals, and to generate the N short indicating signals, and wherein when the ith open fault signal of the N open fault signals is valid, and if the ith detecting voltage is less than the short threshold voltage for a preset time period, the ith short indicating signal is valid.

A short to ground and open protecting circuit used in a light emitting diode (LED) driver for powering N LED strings, wherein N is an integer greater than or equal to 1, the LED driver has an output terminal for providing a power supply voltage for the N LED strings and N feedback terminals having N detecting voltages respectively, wherein i is an integer in a range from 1 to N, for each i from 1 to N, the ith LED string of the N LED strings is coupled between the output terminal and the ith feedback terminal of the N feedback terminals, and the ith feedback terminal is configured to have the ith detecting voltage of the N detecting voltages, the short to ground and open protecting circuit comprising:

an open protecting circuit, configured to generate N open fault signals, wherein for each i from 1 to N, when the ith LED string is open, the ith open fault signal is valid;
and
a short to ground protecting circuit, having N input terminals respectively coupled to the N feedback terminals to receive the N detecting voltages, configured to generate N short indicating signals based on the N detecting voltages, wherein for each i from 1 to N, on the premise of the ith open fault signal being valid, if the ith detecting voltage is less than a short threshold voltage for a preset time period, the ith short indicating signal is valid.

A light emitting diode (LED) driver for powering N LED strings, wherein N is an integer greater than or equal to 1, the LED driver has an output terminal and N feedback terminals having N detecting voltages respectively, wherein i is an integer in a range from 1 to N, for each i from 1 to N, the ith LED string of the N LED strings is coupled between the output terminal and the ith feedback terminal of the N feedback terminals, and the ith feedback terminal is configured to have the ith detecting voltage of the N detecting voltages, the LED driver comprising:

a voltage regulating circuit, coupled to the output terminal to provide a power supply voltage for the N LED strings;
a current regulating circuit, coupled to the N LED strings and configured to regulate the currents flowing through the N LED strings based on a current regulating signal;
a feedback selecting circuit, having N input terminals respectively coupled to the N feedback terminals to receive the N detecting voltages, and configured to provide the minimum one of the N detecting voltages to the voltage regulating circuit to regulate the power supply voltage;
an open protecting circuit, configured to generate N open fault signals, wherein for each i from 1 to N, when the ith LED string is open, the ith LED fault signal is valid;
and
a short to ground protecting circuit, configured to receive a short threshold voltage and N open fault signals, and to generate N short indicating signals, wherein for each i from 1 to N, on the premise of the ith open fault signal being valid, if the ith detecting voltage is less than a short threshold voltage for a preset time period, the ith short indicating signal is valid.

3 more elements

Dependencies are inferred from the claim text.

Short to ground and open protecting circuit, and associated protecting method

Life of this patent

Short to ground and open protecting circuit, and associated protecting method

Life of this patent

Abstract

Claims20