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SLCA001A–July 2016–Revised July 2016
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Copyright © 2016, Texas Instruments Incorporated
Designing With the TRS3122E
Application Report
SLCA001A–July 2016–Revised July 2016
Designing With the TRS3122E
ABSTRACT
As RS-232 continues to withstand the test of time and serial port evolution, standard RS-232 transceivers
must evolve to meet current and new system level needs. Applications demand smaller form factor, faster
speed, lower power, cost efficiency, robustness, reliability, and ease of use. Most of the current standard
solutions (that is, TRS3232, TRS3243, and so forth) meet these needs. Higher speed and lower power
come from reducing RS-232 voltage levels from ±12 V to ±5.4 V. Reduced voltage swings switch faster
with less capacitive current demand. TRS3122E improves ease of use with internal voltage translation
between logic and charge pump V
CC
level. Alternatively, TRS3122E can be powered with a single 1.8-V,
3.3-V, or 5-V supply. TRS3122E has a small package size, 1-Mb/s speed and IEC 61000-4-2 ESD
protection, ±15 kV Air-Gap, and ±8 kV Contact.
This application note will go beyond what is in the datasheet and explain how key specs and features can
improve the users system in order to aid the user in taking advantage of the key enhancements and
features of this device. This application note will explain in detail:
• Extended Supply Operation: 1.8 V to 5.5 V
• Charge Pump Tripler Operation
• Auto-Powerdown-Plus
• Layout
• Key Design Care-Abouts
Contents
1 Extended Supply Operation ................................................................................................ 2
2 Tripler Charge Pump Operation ........................................................................................... 3
3 Auto-Powerdown-Plus....................................................................................................... 4
4 Layout ......................................................................................................................... 4
5 Key Design Care-Abouts ................................................................................................... 5
List of Figures
1 Previous Generation Solution.............................................................................................. 2
2 TRS3122E Diagram......................................................................................................... 3
3 Charge Pump Regulator.................................................................................................... 4
4 TRS3122E 2-Layer Metal Example Layout .............................................................................. 5
