TI SN75C3221DBRE4

The SN65C3221 and SN75C3221 consist of one line driver, one line receiver, and a dual charge pump circuit, with ±15 kV ESD protection on all pins, including the grounded serial port connection pins. These devices provide the electrical interface between an asynchronous communication controller and a serial port connector. The charge pump and four small external capacitors allow the devices to operate from a single 3 V to 5.5 V supply. These devices support data signaling rates up to 1 Mbit/s, with driver output slew rates of 24 V/μs to 150 V/μs. Flexible power management control options are available when the serial port is inactive. When FORCEON is low and FORCEOFF is high, the automatic power-down function is enabled. In this operating mode, if no valid RS-232 signal is detected at the receiver input, the driver outputs are disabled. If FORCEOFF is set low and EN is high, both the driver and receiver are shut down, reducing supply current to 1 μA. Disconnecting the serial port or powering down the peripheral driver triggers the automatic power-down state. Automatic power-down can be disabled by setting both FORCEON and FORCEOFF high. When automatic power-down is enabled, the device automatically activates when a valid signal is applied to the receiver input. The INVALID output notifies the user whether an RS-232 signal is present at the receiver input. INVALID is high (valid data) if the receiver input voltage is greater than 2.7 V or less than −2.7 V, or remains between −0.3 V and 0.3 V for less than 30 μs. INVALID is low (invalid data) if the receiver input voltage remains between −0.3 V and 0.3 V for more than 30 μs.

• VCC supply voltage: 3 V to 5.5 V
• Data rate up to 1 Mbit/s
• Low standby current, typical 1 μA
• External capacitance: 4 × 0.1 μF
• 5 V logic input compatible with 3.3 V supply
• RS-232 bus pin ESD protection exceeds ±15 kV HBM
• Auto-powerdown automatically disables drivers to conserve power

• Battery-powered, handheld, and portable devices
• PDAs and palmtop computers
• Laptops, sub-notebooks, and portable computers
• Digital cameras
• Mobile phones and wireless devices