MC8721C

MC8721C is a monolithic slave interface chip developed for M-Bus communication standard (EN1434-3) applications. The interface chip accommodates potential differences between slave and master stations, with no polarity requirement for bus connections. The chip can be powered by the master station via the bus, eliminating the need for a separate power supply in the slave station. During reception, the chip incorporates a built-in dynamic level detection circuit that can be adjusted according to bus length. The transmission current is fixed at 20mA. The MC8721C adopts an 8-PIN design with a miniaturized package, reducing PCB footprint and enabling a highly reliable, high-performance M-Bus terminal interface with minimal external components. In addition to the M-Bus compliant transmit/receive circuitry, the MC8721C integrates a 5V and a 3.3V DC voltage regulator, capable of providing up to 30mA drive current to the terminal (multiplexed with the transmit current when RX is pulled "low"). The static bus current of the chip is determined by the external resistor RRIDD connected to the RIDD pin (once the static current is set by RRIDD, it remains independent of the output load current — i.e., load variations do not affect the static current value). When RX is pulled "low", the transmit current is added to the drive current, further enhancing the chip's drive capability.

Applications

• Meter-Bus communication systems & various communication devices
• Smart gas/heat meter reading, intelligent sensor networks
• Industrial control LAN systems, smart home control networks

Key features

• Compliant with EN1434-3 standard
• Non-polarity transmission
• Receiver with dynamic level recognition
• Bus high-level voltage compatible from 18V to 45V
• 20mA reusable current source
• 5V and 3.3V regulated output, max current exceeding 30mA
• Standard communication rates from 1200bps to 9600bps
• SOP8 compact package