Description of TRS3221ECPW
A single VCC supply powers the single driver, single receiver TRS3221E RS-232 system. The IEC G1000-4-2 ESD protection is provided through the RS-232 pins. The TRS3221ECPW offers the electrical interface between an asynchronous communication controller and the serial-port connector and complies with TIA/EIA-232-F specifications.
Four tiny external capacitors and the charge pump enable operation from a single 3-V to 5.5-V supply. TRS3221ECPW devices have a maximum driver output slew rate of 30 V/s and data signaling rates of up to 250 kbit/s.
When the serial port is not in use, flexible control options for power management are available. When FORCEON and FORCEOFF are both low, the auto power down feature is active. In this mode of operation, the driver output is deactivated if the device does not detect a legitimate RS-232 signal on the receiver input.
The driver and receiver are both turned off, and the supply current is lowered to 1 A, if FORCEOFF is set low and EN is high. The serial port must be disconnected, or the peripheral drivers must be disabled, to trigger the auto-power down condition. In situations where FORCEON and FORCEOFF are high, auto power down can be deactivated.
When auto-power down is turned on, the gadget automatically turns on when a good signal is applied to the receiver input. If an RS-232 signal is present at the receiver input, the user is alerted by the INVALID output.
If the receiver input voltage is greater than 2.7 V or less than -2.7 V, or if it has been between -0.3 V and 0.3 V for less than 30 s, INVALID is high (good data). If the receiver input voltage is between -0.3 V and 0.3 V for more than 30 s, INVALID is low (invalid data).