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SLCU001 – May 2016
Copyright © 2016, Texas Instruments Incorporated
TRS3122EEVM User's Guide
Applications
Any application that needs short range point to point full duplex data communications with hardware flow
control.
•
Remote Radio Unit (RRU)
•
Base Band Unit (BBU)
•
Electronic Point of Sale (EPOS)
•
Diagnostics & Data Transmission Battery-Powered Equipment
Setup
The VCC screw terminal point needs to be supplied with external power; 1.8 V or 3.3 V is recommended.
The VL screw terminal point needs to be supplied with external power; 1.8 V to VCC is recommended.
The GND screw terminal point is the ground connection for the TRS3122EEVM.
The DB9 connector mates with a personal computer's RS-232 port or a USB to RS-232 adapter. For initial
testing, external wires can be added to screw terminals; CTS2 to RTS2 and TX2 to RX2 to loop back the
signal.
The ideal usage involves connecting the terminal block data and control lines to a system that has an
UART (Universal asynchronous receiver/transmitter) onboard.
The EVM has pull up resistors on the TRS3122E FORCEOFF and FORCEON pins to keep both driver
and receiver active. If desired, these signal can be driven by the external system to fully control all the
features of auto-powerdown plus circuitry. The system may also benefit from monitoring the INVALID
output to detect if an active connection has been made to the RS-232 port.
Usage at 5 V
The capacitors installed on the TRS3122EEVM were selected for VCC = 1.8 V and VCC = 3.3 V
operation. It is required to change some of the onboard capacitors for 5 V testing.
Capacitor Changes
VCC voltage
C1
C2
C4
C5
1.8 V, 3.3 V
100 nF
100 nF
100 nF
100 nF
5 V
47 nF
330 nF
330 nF
330 nF
