Single Transmitter/Receiver RS-232 16-Pin SSOP T/R

The TRSF3221E consists of one line driver, one line receiver, and a dual charge-pump circuit with ±15-kV IEC ESD protection pin to pin (serial-port connection pins, including GND). The TRSF3221E 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 TRSF3221E 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 TRSF3221E does not sense a valid RS-232 signal on the receiver input, the driver output is disabled. If FORCEOFF\ is set low and the enable (EN\) input 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.

ESD Protection for RS-232 Pins

• ±15-kV Human-Body Model (HBM)
• ±8-kV IEC 61000-4-2 Contact Discharge
• ±15-kV IEC 61000-4-2 Air-Gap Discharge

Operates With 3-V to 5.5-V V_CC Supply

Operates up to 1 Mbit/s

Low Standby Current . . . 1 µA Typ

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 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