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Schematic and Layout
3 Schematic and Layout
The TRS3221RGTEVM has simple connections to all necessary pins of the TRS3221RGT transceiver device,
and jumpers where necessary to provide flexibility for device. The TRS3221RGTEVM provides test points for all
RS-232 (TX1, RX1) and logic (TX2, RX2) communication lines. Additionally test points of GND, VCC, and
charge pump output voltage are available for probing and evaluation.
3.1 Schematic
The schematic is shown in
RX2
RX2
J2
INV
ON
1
2
TX2
3
4
5
6
TX2
7
8
OFF
9
10
EN
11
12
13
14
15
16
VCC
C6
1uF
GND
Connection
J1
J2
V+
V-
Power and logic signal go through the J1 connector.
Connection
1
2
3
4
5
6
7
8
9
The female DB9 port
(Figure
pinout. The TRS3221RGT female port is DCE to mate with a computer male DTE port. The pin names are
counterintuitive on the DCE side. For example, the RX pin on EVM is connected to a driver and TX connects to a
receiver. The reason pins 4 and 6 are shorted together by a 0 Ω resistor is to loopback the unused handshaking
lines.
4
TRS3221 EVM User's Guide
Figure
3-1. The function of each jumper and test point is listed in
VCC
C5
V+
12
C3
GND
VCC
16V
10V
15
0.1uF
0.1uF
8
R1
R2
6
10.0k
10.0k
ON
OFF
9
13
EN
14
16
VCC
EN
1
C1
16V
2
R3
R4
R8
0.1uF
C2
3
10.0k
10.0k
10.0k
16V
ON
OFF
0.1uF
GND
Figure 3-1. TRS3221RGTEVM Schematic
Table 3-1. Jumpers and Test Points
Type
9-pin connector
16-pin jumper
Test point
Test point
Table 3-2. J1 pin connection
Type
NC
Output
Input
Loopback
GND
Loopback
NC
NC
NC
3-2) provides access to the TRS3221RGT device through a standard RS-232
Copyright © 2020 Texas Instruments Incorporated
U0
VCC
V+
10
TIN
TOUT
5
ROUT
RIN
INV
7
FORCEON
INVALID
FORCEOFF
EN
V-
4
C1+
V-
C1-
C4
11
GND
16V
C2+
0.1uF
17
C2-
Thermal_Pad
TRS3221EIRGTR
GND
Description
Female DB9 connector to
connect to PC
Used for supply and TTL signal
Charge pump positive output
Charge pump negative output
Table 3-2
lists each pin's connection.
Description
Not connected
RX1, pin 10 of transceiver
TX1, pin 5 of transceiver
Connected to pin 6
Ground
Connected to pin 4
Not connected
Not connected
Not connected
www.ti.com
Table
3-1.
RX1
R6
RX1
0
GND
TX1
R5
J1
TX1
1
618009231121
6
0
2
7
3
8
R7
4
9
0
5
SLLU328 – DECEMBER 2020
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