1 Features

• Meets or exceeds the requirements of the TIA/

EIA-485A and TIA/EIA-232F standards

• 2 transmitters, 2 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 mode

• Shutdown pin for extremely low current

consumption (10μA typical) in disabled state

• Glitch-free power-up and 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 5mm x 5mm

VQFN-32 package

2 Applications

• Industrial PC

• Factory automation and control

• HVAC systems

• Building automation

• Point-of-sale terminals

• Grid infrastructure

• Industrial transport

3 Description

THVD4421 is a highly integrated and robust

multiprotocol transceiver supporting RS-232, RS-422

and RS-485 physical layers. The device has two

transmitters and two receivers to enable 2T2R

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 is

provided so no external components are needed to

realize a fully-functional communication port. These

devices have slew rate select feature that enables

them to be used at two maximum speeds based on

the SLR pin setting.

These devices feature integrated Level 4 IEC ESD

protection, eliminating the need for external systemlevel

protection components. Diagnostic loopback

mode for RS-232 is provided to check for logic to bus

and bus to logic path functional integrity and check

for cable or 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) suited for

power-sensitive applications. The device needs 3V to

5.5V supply that powers the charge pump for RS-232

and the drivers and receivers for both RS-232 and

RS-485. A separate logic supply VIO (1.65V to 5.5V)

enables interface with low level microcontrollers.