Qualified for Automotive Applications

Operates With 3-V to 5.5-V VCC Supply

Operates Up To 1 Mbit/s

Low Standby Current . . . 1 μA Typical

External Capacitors . . . 4 × 0.1 μF

Accepts 5-V Logic Input With 3.3-V Supply

RS-232 Bus-Pin ESD Protection Exceeds

±15 kV Using Human-Body Model (HBM)

Auto-Powerdown Feature Automatically

Disables Drivers for Power Savings

Applications

− Battery-Powered, Hand-Held, and

Portable Equipment

− PDAs and Palmtop PCs

− Notebooks, Sub-Notebooks, and Laptops

− Digital Cameras

− Mobile Phones and Wireless Devices

description/ordering information

The SN65C3221 consists of one line driver, one line receiver, and a dual charge-pump circuit with ±15-kV ESD

protection pin to pin (serial-port connection pins, including GND). This device 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. This device operates at data

signaling rates up to 1 Mbit/s and a driver output slew rate of 24 V/μs to 150 V/μs.

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 on the receiver input, the driver output is disabled.

If FORCEOFF is set low and EN is high, both the driver and receiver are shut off, and the supply current is

reduced to 1 μA. Disconnecting the serial port or turning off the peripheral drivers causes the auto-powerdown

condition to occur. Auto-powerdown can be disabled when FORCEON and FORCEOFF are high. With

auto-powerdown enabled, the device is activated automatically when a valid signal is applied to the receiver

input. The INVALID output notifies the user if 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 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. See Figure 5 for receiver input levels.