Abstract: A constant current control circuit includes a current source output module and at least two output circuits. Each of the output circuits includes an automatic constant current regulating module, a power transistor drive and control module electrically coupled to automatic constant current regulating module, and a load module formed of one or more LED devices and electrically coupled to a power transistor drive and control module. The constant current control circuit in operation tracks changes in current of each output circuit and regulates the currents of all the output circuits accordingly.

Abstract: The invention relates to digital television authentication system and method. The system includes a digital television having a digital television master chip; an SIM card module with a built-in SIM card, connected to the digital television master chip, and an authentication server wirelessly connected to the SIM card. The SIM card module includes a symmetric key generation unit used for generating a symmetric encryption key CT according to a Session Key (SEK) received by the SIM card and an identity (ID) of the SIM card; and a CW acquisition unit used for decrypting, according to the symmetric encryption key CT, an ECW sent by the authentication server, to obtain a CW. The authentication server includes an SEK generation unit used for randomly generating a string and taking the string as an SEK; and an SEK sending unit used for sending the SEK to the SIM card module.

Abstract: A constant current control circuit includes a current source output module and at least two output circuits. Each of the output circuits includes an automatic constant current regulating module, a power transistor drive and control module electrically coupled to automatic constant current regulating module, and a load module formed of one or more LED devices and electrically coupled to a power transistor drive and control module. The constant current control circuit in operation tracks changes in current of each output circuit and regulates the currents of all the output circuits accordingly.