1 Features
• Meets or exceeds the requirements of the TIA/
EIA-485A and TIA/EIA-232F standards
• 3 transmitters, 5 receivers for RS-232
• 1 transmitter, 1 receiver for RS-485
• On-chip switchable 120Ω termination resistor for
RS-485 mode
• Integrated charge-pump for RS-232 signaling
• 3V to 5.5V supply voltage
• 1.65V to 5.5V supply for logic data and control
signals
• RS-485 differential output exceeds 2.1V for
PROFIBUS compatibility with 5V supply
• Large output swing (typical ± 9V) for RS-232 mode
• SLR Pin Selectable Data Rates:
– RS-232 3T5R mode: 250kbps and 1Mbps
– RS-485 half-duplex and full-duplex mode:
500kbps and 20Mbps
• Bus I/O protection
– ±16kV HBM ESD
– ±8kV IEC 61000-4-2 contact and ±15kV air-gap
discharge
– ±4kV IEC 61000-4-4 fast transient burst
• Diagnostic loopback for both RS-232 and RS-485
modes
• Pin-selectable diagnostic loopback
• Shutdown pin for low current consumption (10μA
typical) in disabled state
• Glitch-free power-up/down for hot plug-in capability
• 1/8 unit load (up to 256 bus nodes) for RS-485
• Open, short, and idle bus failsafe for RS-485
receiver
• Bus short-circuit protection, thermal shutdown
• Extended ambient temperature range: -40°C to
125°C
• Space-saving thermally efficient 6mm x 6mm
VQFN-40 package
• Pin compatible with industry standard

2 Applications
• Industrial PC
• Factory automation and control
• HVAC systems
• Building automation
• Point-of-sale terminals
• Grid infrastructure
• Industrial Transport

3 Description
THVD4431A is a highly integrated and robust
Multiprotocol transceiver supporting RS-232, RS-422
and RS-485 physical layers. The device has three
transmitters and five receivers to enable 3T5R
RS-232 port. The device also integrates one
transmitter and one receiver to enable half and full
duplex RS-485 port. MODE selection pins enable
shared bus and logic pins for the protocols to share
a common single connector. Integrated termination for
RS-485 bus pins and for RS-232 receiver inputs need
no external components to realize a fully-functional
communication port. The device has a slew rate
select feature that enables the device for use at two
maximum speeds based on the SLR pin setting.
The device features integrated Level 4 IEC ESD
protection, eliminating the need for external systemlevel
protection components. Diagnostic loopback
mode for both RS-232 and RS-485 is provided to
check for logic to bus and bus to logic path functional
integrity and check for cable and connector shorts. In
addition, the RS-485 receiver fail-safe feature drives
logic high on received logic output when the bus
inputs are open or shorted together or when the bus
is idle. Shutdown mode consumes ultra-low current
(10μA typical), which is good for power-sensitive
applications. The device needs 3 to 5.5V supply that
powers the charge pump for RS-232 and the drivers
or receivers for both RS-232 and RS-485. A separate
logic supply VIO (1.65V to 5.5V) enables interface with
low level microcontrollers.