TIDUFE6A September 2025 – December 2025
To properly interface with the RS-232 standard, a voltage translation system is required to convert between the 3.3V domain on the board and from the 12V on the port. To facilitate the translation, the design uses a TRSF3221E device. The TRSF3221E device is capable of driving the higher voltage signals on the RS-232 port from only the 3.3V DVCC through a charge pump system. The TRSF3221E consists of a line driver, a line receiver, and a dual charge-pump circuit with ±15kV IEC ESD protection pin to pin (serial-port connection pins, including GND). The charge pump and four small external capacitors allow operation from a single 3V to 5.5V supply. The TRSF3221E operates at data signaling rates up to 1Mbit/s and a driver output slew rate of 24V/μs to 150V/μs.
Figure 2-23 RS-232 Circuit