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FEATURES

DB OR PW PACKAGE

(TOP VIEW)

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EN

C1+

V+

C1−

C2+

C2−

V−

RIN

FORCEOFF

GND

DOUT

FORCEON

DIN

INVALID

ROUT

APPLICATIONS

DESCRIPTION/ORDERING INFORMATION

TRSF3221

3-V TO 5.5-V SINGLE-CHANNEL RS-232 COMPATIBLE LINE DRIVER/RECEIVER

SLLS857 – AUGUST 2007

www.ti.com

• Operates With 3-V to 5.5-V V

• 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 Human-Body Model (HBM)

• Auto-Powerdown Feature Automatically

Disables Drivers for Power Savings

• Battery-Powered, Hand-Held, and Portable

Equipment

• PDAs and Palmtop PCs

• Notebooks, Sub-Notebooks, and Laptops

• Digital Cameras

• Mobile Phones and Wireless Devices

The TRSF3221 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 TRSF3221 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 TRSF3221 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 TRSF3221 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. See Figure 5 for receiver input levels.

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Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

PRODUCTION DATA information is current as of publication date.

Copyright © 2007, Texas Instruments Incorporated

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.