US 11,057,976 B2
Short to ground and open protecting circuit, and associated protecting method
Shufa Jiang, Chengdu (CN); Junxin Tan, Hangzhou (CN); and Bo Yu, Hangzhou (CN)
Assigned to Chengdu Monolithic Power Systems Co., Ltd., Chengdu (CN)
Filed by Chengdu Monolithic Power Systems Co., Ltd., Chengdu (CN)
Filed on Nov. 23, 2020, as Appl. No. 17/101,185.
Claims priority of application No. 201911210810.9 (CN), filed on Dec. 2, 2019.
Prior Publication US 2021/0168917 A1, Jun. 3, 2021
Int. Cl. H05B 45/50 (2020.01); H05B 47/20 (2020.01); H05B 45/30 (2020.01)
CPC H05B 45/50 (2020.01) [H05B 45/30 (2020.01); H05B 47/20 (2020.01)] 20 Claims
OG exemplary drawing
 
1. 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.