SLLS808A JULY   2007  – November 2016 TRS202

UNLESS OTHERWISE NOTED, this document contains PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1  Absolute Maximum Ratings
    2. 6.2  ESD Ratings
    3. 6.3  Recommended Operating Conditions
    4. 6.4  Thermal Information
    5. 6.5  Electrical Characteristics
    6. 6.6  Electrical Characteristics: Driver
    7. 6.7  Electrical Characteristics: Receiver
    8. 6.8  Switching Characteristics: Driver
    9. 6.9  Switching Characteristics: Receiver
    10. 6.10 Typical Characteristics
  7. 7 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Power
      2. 8.3.2 RS-232 Driver
      3. 8.3.3 RS-232 Receiver
    4. 8.4 Device Functional Modes
      1. 8.4.1 VCC Powered by 5 V
      2. 8.4.2 VCC Unpowered
      3. 8.4.3 Truth Tables
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Capacitor Selection
      2. 9.1.2 Electrostatic Discharge (ESD) Protection
      3. 9.1.3 ESD Test Conditions
      4. 9.1.4 Human-Body Model (HBM)
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Capacitor Selection
      3. 9.2.3 Application Curve
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Receiving Notification of Documentation Updates
    2. 12.2 Community Resources
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

9 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

9.1 Application Information

For proper operation, add capacitors as shown in Figure 12. Pins 9 through 12 connect to UART or general purpose logic lines. RS-232 lines on pins 7, 8, 13, and 14 connect to a connector or cable.

9.1.1 Capacitor Selection

The capacitor type used for C1–C4 is not critical for proper operation. The TRS202 requires 0.1-µF capacitors, although capacitors up to 10 µF can be used without harm. Ceramic dielectrics are suggested for the 0.1-µF capacitors. When using the minimum recommended capacitor values, make sure the capacitance value does not degrade excessively as the operating temperature varies. If in doubt, use capacitors with a larger (for example, 2×) nominal value. The capacitors' effective series resistance (ESR), which usually rises at low temperatures, influences the amount of ripple on V+ and V–.

Use larger capacitors (up to 10 µF) to reduce the output impedance at V+ and V–.

Bypass VCC to ground with at least 0.1 µF. In applications sensitive to power-supply noise generated by the charge pumps, decouple VCC to ground with a capacitor the same size as (or larger than) the charge-pump capacitors (C1 to C4).

9.1.2 Electrostatic Discharge (ESD) Protection

TI TRS202 devices have standard ESD protection structures incorporated on the pins to protect against electrostatic discharges encountered during assembly and handling. In addition, the RS232 bus pins (driver outputs and receiver inputs) of these devices have an extra level of ESD protection. Advanced ESD structures were designed to successfully protect these bus pins against ESD discharge of ±15 kV when powered down.

9.1.3 ESD Test Conditions

Stringent ESD testing is performed by TI, based on various conditions and procedures. Contact TI for a reliability report that documents test setup, methodology, and results.

9.1.4 Human-Body Model (HBM)

The HBM of ESD testing is shown in Figure 10. Figure 11 shows the current waveform that is generated during a discharge into a low impedance. The model consists of a 100-pF capacitor, charged to the ESD voltage of concern, and subsequently discharged into the device under test (DUT) through a 1.5-kΩ resistor.

TRS202 HBM_ESD_test_lls808.gif Figure 10. HBM ESD Test Circuit
TRS202 HBM_curr_wave_lls808.gif Figure 11. Typical HBM Current Waveform

9.2 Typical Application

Two driver and two receiver channels are supported for full duplex transmission with hardware flow control. The two 5-kΩ resistors are internal to the TRS202.

TRS202 typ_op_cir_lls808.gif Figure 12. Typical Operating Circuit and Capacitor Values

9.2.1 Design Requirements

  • VCC minimum is 4.5 V and maximum is 5.5 V.
  • Maximum recommended bit rate is 120 kbps.

9.2.2 Detailed Design Procedure

9.2.2.1 Capacitor Selection

The capacitor type used for C1 through C4 is not critical for proper operation. The TRS202 requires 0.1-µF capacitors. Capacitors up to 10 µF can be used without harm. Ceramic dielectrics are suggested for the 0.1-µF capacitors. When using the minimum recommended capacitor values, make sure the capacitance value does not degrade excessively as the operating temperature varies. If in doubt, use capacitors with a larger (for example, 2×) nominal value. The capacitors' effective series resistance (ESR), which usually rises at low temperatures, influences the amount of ripple on V+ and V–.

Use larger capacitors (up to 10 µF) to reduce the output impedance at V+ and V–.

Bypass VCC to ground with at least 0.1 µF. In applications sensitive to power-supply noise generated by the charge pumps, decouple VCC to ground with a capacitor the same size as (or larger than) the charge-pump capacitors (C1 to C4).

9.2.3 Application Curve

TRS202 D006_LB_1NF.gif
120 kbit/s, 1-nF load
Figure 13. Driver and Receiver Loopback Signal