The SC8521 can be used in infrared remote control transmitters. It generates output pulses, in accordance with the RC5 protocol, when a key is pressed. The IC does not contain a software programmable processor. However, it does contain a ROM in which the codes that have to be transmitted are stored. The oscillator frequency may be optionally chosen as 432KHz. For 432KHz additional external capacitors must be connected. When a key in the key-matrix is pressed a driveline will be connected to a sense line.