FEATURES

· RS-232 Bus-Pin ESD Protection Exceeds

±15 kV Using Human-Body Model (HBM)

· Meet or Exceed the Requirements of

TIA/EIA-232-F and ITU v.28 Standards

· Operate With 3-V to 5.5-V VCC Supply

· Operate up to 1000 kbit/s

· Five Drivers and Three Receivers

· Auto-Powerdown Plus Feature Enables

Flexible Power-Down Mode

· Low Standby Current . . . 1 mA Typical

· External Capacitors . . . 4 ´ 0.1 mF

· Accept 5-V Logic Input With 3.3-V Supply

· Always-Active Noninverting Receiver Output

(ROUT1B)

· ESD Protection for RS-232 Interface Pins

– ±15 kV – Human-Body Model (HBM)

– ±8 kV – IEC61000-4-2, Contact Discharge

– ±15 kV – IEC61000-4-2, Air-Gap Discharge

APPLICATIONS

· Battery-Powered Systems

· PDAs

· Notebooks

· Subnotebooks

· Laptops

· Palmtop PCs

· Hand-Held Equipment

· Modems

· Printers

DESCRIPTION/ORDERING INFORMATION

The SN65C3238E and SN75C3238E consist of five line drivers, three line receivers, and a dual charge-pump

circuit with ±15-kV ESD (HBM) protection on the driver output (DOUT) and receiver input (RIN) terminals. The

devices meet the requirements of TIA/EIA-232-F and provide the electrical interface between notebook and

subnotebook computer applications. The charge pump and four small external capacitors allow operation from a

single 3-V to 5.5-V supply. In addition, the devices include an always-active noninverting output (ROUT1B),

which allows applications using the ring indicator to transmit data while the device is powered down. These

devices operate at data signaling rates up to 1000 kbit/s.

Flexible control options for power management are featured when the serial port and driver inputs are inactive.

The auto-powerdown plus feature functions when FORCEON is low and FORCEOFF is high. During this mode

of operation, if the devices do not sense valid signal transitions on all receiver and driver inputs for

approximately 30 s, the built-in charge pump and drivers are powered down, reducing the supply current to

1 mA. By disconnecting the serial port or placing the peripheral drivers off, auto-powerdown plus occurs if there

is no activity in the logic levels for the driver inputs. Auto-powerdown plus can be disabled when FORCEON and

FORCEOFF are high. With auto-powerdown plus enabled, the devices activate automatically when a valid signal

is applied to any receiver or driver input. INVALID is high (valid data) if any 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 ms. INVALID is low (invalid

data) if all receiver input voltages are between –0.3 V and 0.3 V for more than 30 ms. Refer to Figure 5 for

receiver input levels.