1FEATURES
• Meter-Bus Transceiver (for Slave) Meets
Standard EN1434-3
• Receiver Logic With Dynamic Level
Recognition
• Adjustable Constant-Current Sink via Resistor
• Polarity Independent
• Power-Fail Function
• Module Supply Voltage Switch
• 3.3-V Constant Voltage Source
• Remote Powering
• Up to 9600 Baud in Half Duplex for UART
Protocol
• Slave Power Support
– Supply From Meter-Bus via Output VDD
– Supply From Meter-Bus via Output VDD or
From Backup Battery
– Supply From Battery – Meter-Bus Active for
Data Transmission Only

DESCRIPTION
TSS721A is a single chip transceiver developed for Meter-Bus standard (EN1434-3) applications.
The TSS721A interface circuit adjusts the different potentials between a slave system and the Meter- Bus
master. The connection to the bus is polarity independent and supports full galvanic slave isolation with
optocouplers.
The circuit is supplied by the master via the bus. Therefore, this circuit offers no additional load for the slave
battery. A power-fail function is integrated.
The receiver has dynamic level recognition, and the transmitter has a programmable current sink.
A 3.3-V voltage regulator, with power reserve for a delayed switch off at bus fault, is integrated.