SP3244E Datasheet, PDF (13/22 Pages) Sipex Corporation – 3.0V to 5.5V RS-232 Transceivers with Auto On-Line® Plus

Auto On-line^® Plus provides greater power
savings in typical operation because the trans-
ceiver will go into low power standby mode
unless a communication link is in use. Signals
such as CTS, RTS, DTR, DSR, or RI will typi-
cally change signal-state to establish hand-
shaking before any actual data-communication
takes place. Transitions on these handshake
signals will wake up the Auto On-line^® Plus
transceiver to prepare it for sending data
(tONLINE 100µs typical).
Receivers remain active to detect incoming
signals in Auto On-line^® Plus standby mode.
Receiver outputs may be disabled by enter-
ing manual shutdown by driving SHUTDOWN
pin to logic 0. A special non-inverted receiver
output R2OUT remains active in all modes,
including SHUTDOWN pin at logic 0.
In some applications if there is a significant
delay (greater than tOFFLINE) between the
handshaking transitions and the start of data
communication the transceiver may enter
Auto On-Line^® Plus standby mode before data
communication begins. The tOFFLINE interval
is at least 15 seconds and no longer than 60
seconds.
In applications where the transceiver needs to
remain active anytime it is connected to live
RS-232 signals, even if those signals remain
idle for longer than tOFFLINE, then the STATUS
output may be used to drive the ONLINE pin.
The STATUS output pin functions the same in
both Auto On-line^® and Auto On-line^® Plus de-
vices. STATUS will output logic 1 if any of the
receiver inputs are driven greater than ±2.7V
magnitude by incoming RS-232 signals and
drives logic 0 if receiver inputs are floating or
driven to ground. Driving the ONLINE pin with
the STATUS output disables Auto On-line^® Plus
(Forced On-Line) whenever RS-232 voltages
are seen on any receiver inputs. If no RS-232
voltages are seen on the receiver inputs the
Auto On-line^® Plus transceiver will still activate
its charge pump and driver outputs when the
driver inputs are active. This allows the trans-
ceiver to signal a remote Auto On-Line^® or Auto
On-Line^® Plus, on the other end of the data
cable, to wake up.
DESCRIPTION
modes, including SHUTDOWN pin at logic 0.
Connecting STATUS output to drive both
ONLINE and SHUTDOWN will wake the trans-
ceiver if any receiver inputs are driven greater
than ±2.7V magnitude and put the transceiver
into Forced Shutdown mode if all receiver
inputs are floating or driven to ground.
±15KV ESD PROTECTION
ESD-protection structures are incorporated
on all pins to protect against electrostatic
discharges encountered during handling and
assembly. The driver output and receiver inputs
of the SP3244E/3245E have extra protection
against static electricity. Sipex uses state-of-
the-art structures to protect these pins against
ESD of ±15kV without damage. The ESD struc-
tures withstand high ESD in all states: normal
operation, shutdown, and powered down. After
an ESD event, the SP3244E/3245E keep work-
ing without latch-up or damage.
ESD protection can be tested in various ways.
The transmitter outputs and receiver inputs
of the SP3244E/3245E are characterized for
protection to the following limits:
• ±15kV using the Human Body Model
• ±8kV using the Contact Discharge
method specified in IEC 1000-4-2
• ±15kV using the Air-Gap Discharge method
specified in IEC 1000-4-2
The STATUS output pin remains active in all
Rev M 10/9/06
SP3244E-SP3245E, 3.0V to 5.5V RS-232 Transceivers with Auto On-Line^® Plus
13
© Copyright 2006 Sipex Corporation