SLLU320 November   2020 TRS3232E , TRSF3232E

 

  1. 1Introduction
    1. 1.1 Features
    2. 1.2 Applications
    3. 1.3 Description
  2. 2Test Setup and Results
    1. 2.1 Overview and Basic Operation Settings
  3. 3Board Layout
  4. 4Schematic and Layout
    1. 4.1 Schematic
    2. 4.2 Bill of Materials
  5. 5Trademarks

2.1 Overview and Basic Operation Settings

Transceiver VCC power supply (pin 16 of J2) and GND (pin 15 of J2): The basic setup of the TRS3232RGTEVM uses a single 3.3-V or 5-V power supply to evaluate the transceiver’s performance. To power the transceiver, connect the 3.3-V or 5-V Vcc supply to pin 16 of J2 jumper and GND to pin 15 of J2. The power supplied should meet the required specification of VCC for the transceiver being tested.

The capacitors installed on the TRS3232RGTEVM were selected for VCC = 3.3-V operation. It is required to change some of the onboard capacitors for 5-V testing (Table 2-1).

Table 2-1 Capacitor configuration
C1 C2 C3 C4
3.3V 100nF 100nF 100nF 100nF
5.0V 47nF 330nF 330nF 330nF

(optional) Charge pump output (V+ and V-): TRS3232RGT has an internal charge pump circuit to generate RS-232 signaling (Ref 1). Before starting the communication, the charge pump operation can be checked by monitoring these two test points.

TIN input (pin 8 of J2): Connect the function generator to pin 8 of the J2 header on the board. Set the function generator to generate a square wave of a certain frequency, 50% duty cycle, the low voltage level to 0 V, and the high level to 5-V. This clock signal simulates the TTL data from MCU. Alternatively PRBS data from a signal generator can be transmitted. Please note the data rate is not recommended to be faster than the specification in the datasheet.

DOUT output (pin 2 of J1): Connect an oscilloscope probe to pin 2 of J1 on the board. Setup the oscilloscope for proper time and voltage per division. Allow room to show three periods of bit-long waveform on the oscilloscope. The received RS-232 signal should match the transmitted logic data. This indicates that the driver of TRS3232RGT is operating correctly.

(optional) Loopback: Connect pin 3 of J1 to pin 2 of J1. By shorting these two pins, the transmitted RS-232 signal is looped back to the receiver of TRS3232RGT. Connect an oscilloscope probe to pin 6 of J2 on the board. Setup the oscilloscope for proper time and voltage per division. Allow room to show three periods of bit-long waveform on the oscilloscope. The received TTL signal should match the loopback data. This indicates that the receiver of TRS3232RGT is operating correctly.