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.