The TRSF3223E consists of two line drivers,
two line receivers, and a dual charge-pump circuit with ±15-kV ESD protection pin to pin
(serial-port connection pins, including GND). This device meets the requirements of
TIA/EIA-232-F and provides the electrical interface between an asynchronous communication
controller and the serial-port connector. The charge pump and four small external capacitors
allow operation from a single 3-V to 5.5-V supply. The TRSF3223E operates at typical data
signaling rates up to 1000 kbits.Flexible control options for power
management are available when the serial port is inactive. The auto-powerdown feature
functions when FORCEON is low and FORCEOFF is high. During this mode of
operation, if the device does not sense a valid RS-232 signal, the driver outputs are
disabled. If FORCEOFF is set low and EN is high, both drivers and
receivers are shut off, and the supply current is reduced to 1 mA. Disconnecting the serial
port or turning off the peripheral drivers causes auto-powerdown to occur. Auto-powerdown
can be disabled when FORCEON and FORCEOFF are high. With auto-powerdown
enabled, the device is automatically activated when a valid signal is applied to any
receiver input. The INVALID output is used to notify the user if an
RS-232 signal is present at any receiver input. INVALID is high (valid
data) if any receiver input voltage is greater than 2.7 V or less than –2.7 V, or has been
between –0.3 V and 0.3 V for less than 30 µs. INVALID is low (invalid
data) if the receiver input voltage is between –0.3 V and 0.3 V for more than 30 µs. Refer
to for receiver input levels.
