Elmos: Smoke detector IC with bus interface

With the E520.32, Elmos presents a fully programmable platform for an optical smoke detector with a bus interface. The analog, addressable integrated circuit needs just a minimum of external components for setting up the complete system. The E520.32 is a high current driver for the transmitter LED and a high impedance input to voltage conversion of the receiver diode. The component just requires the low supply current of 88µA. 4 kByte Flash ROM and 32 Byte EEPROM for configuration are integrated into the IC.



The 2-wire bus interface supports a supply voltage of 8 to 50V. The configurable 200mA LED driver and the wide photo current input range of 1.5 to 45nA complete the E520.32.

A fast response from the receiver and the 10 bit ADC provide for short transmitter pulses at a high detection rate. Due to the amplifier’s narrow band pass filter characteristics, interference signals and false alarms are avoided. The transmitter pulses and the detected signals are processed by the integrated 8-bit microcontroller. The flexible configurability allows an optimization of the system’s performance; up to 255 detectors can be connected to the bus interface.

The operating temperature range is –55°C to +85°C. The IC comes in a SOIC14 package.