SP3224E Datasheet, PDF (15/23 Pages) Sipex Corporation – 3.0V to 5.5V RS-232 Transceivers with Auto On-Line® Plus

shut down, the charge pumps are turned off.
V+ charge pump output decays to VCC,the
V- output decays to GND. The decay time
will depend on the size of capacitors used
for the charge pump. Once in shutdown, the
time required to exit the shutdown state and
have valid V+ and V- levels is typically 50μs.
When the SP3224E-SP3227E drivers and
internal charge pump are disabled, the sup-
ply current is reduced to 1μA.
THEORY OF OPERATION
Auto On-Line (existing) Device enters low-power mode if receiver inputs see less than valid +/- 3V.
STATUS (or INVALID) signal output indicates if valid signal voltage is at
receivers.
Auto On-Line Plus (new)
Device enters low-power mode if driver inputs or receiver inputs see no
transitions for 30 seconds.Return to full power mode upon any transition on
any driver input or receiver input
Shutdown occurs even if data cable is connected to an active driver, as long
as all inputs remain unchanged
STATUS (or INVALID) signal functions as before.Indicates if valid signal
voltage is present.But has no effect on shutdown
For SP3224E the EN input is replaced with a READY output.READY drives
high when charge pump achieves greater than -4V Vss (V-).Indicates “ready
to transmit.”
Comparison of Auto On-line^® Features
Operating Mode
ONLINE SHDN
Forced Shutdown X
0
Forced On-Line
1
1
|Rin| >
±2.7V
X
X
Idle Inputs
(Rxin &
Txin)
X
X
Txout
Hi-Z
Active
Auto On-Line Plus 0
(Wake when active)
1
X
Active
Active
Auto On Line Plus 0
(Off-Line when idle)
1
X
Idle > 30s Hi-Z
Auto On-Line Plus STATUS 1
(Wake on cable)
Yes
X
Active
Auto On-Line Plus STATUS 1
(Wake when active)
No
Active
Active
Auto On-Line Plus STATUS 1
(Off-Line when idle)
No
Idle > 30s Hi-Z
Auto On-Line
STATUS STATUS Yes
X
(Wake on cable)
Active
Auto On-Line
STATUS STATUS No
X
Hi-Z
(Auto Shutoff)
Auto On-line^® Plus Truth Table
Rxout
Active
Active
Active
Active
Active
Active
Active
Active
Active
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com
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