XRT4000 Datasheet, PDF (20/46 Pages) Exar Corporation – Universal Multiprotocol Serial Interface

XRT4000
Single-Ended or Differential
Max Signal Level
Min Signal Level
Offset Voltage
Rout Differential
Rout Common-Mode
Rout Power Off
Output Slew Rate/Tr,Tf
Clock Frequency
V.35
DIFF
± 660 mV
RL= 100Ω
± 440 mV
RL= 100Ω
N/A
100Ω ± 10%
150Ω ± 15%
N/A
20 ns
20 MHz
V.11
DIFF
|V0| < 6 V
RL=3900Ω
2V < |VT|
>0.5 V0
RL=100Ω
|Vos| < 3V
100Ω
N/A
N/A
20 ns
20 MHz
V.10
Single-Ended
4 < |V0| < 6 V
RL=3900Ω
|VT| > 0.9 V0
RL= 450Ω
N/A
N/A
N/A
N/A
1ms
120 KHz
RS232
Single-Ended
±6V
3000Ω < RL <
7000Ω
±5V
3000Ω < RL <
7000Ω
N/A
N/A
N/A
> 300Ω
< 30 V/µs
256 KHz
Table 5. Transmitter Specification
V.10\V.28 Output Pulse Rise and Fall Time
SLEW_CNTL (pin 47) is an analog output that
controls transmitter pulse rise and fall time for
the V.10 and V.28 modes. Connecting a
resistor, RSLEW, having a value between 0 and
200 kΩ from this pin to ground controls the
rise/fall times for V.10 and the slew rate for V.28
as shown in Figures 15 and 16 respectively.
High-Speed RS232 Mode
When E_232H* (pin 55) is set to logic 0 in
RS232 mode, the transmitters are put is a
special high-speed RS232 mode that can drive
loads of 3000Ω in parallel with 1000pF at
speeds up to 256 KHz.
Power Down Mode
All transmitters and receivers may be powered
down by either setting the pins for control bits
M0, M1 and M2 to logic 1 or by leaving them
open.
Internal Cable Terminations
XRT4000 has fully integrated receiver and
transmitter cable terminations for high speed
signals (RXD, TXD, RXC, TXC, SCTE).
Therefore, no external resistors and/or switches
are necessary to implement the proper line
termination. The schematic diagrams given in
Figures 17 and 18 show the effective receiver
and transmitter terminations respectively for
each mode of operation. When a specific
electrical interface is selected by M0, M1 and
M2, the termination required for that interface is
also automatically chosen. The XRT4000
eliminates double termination problems and
makes point to multipoint operation possible in
the V.11 mode by providing the option for
disabling the internal input termination on high
speed receivers.
Glitch Filters
Occasional extraneous glitches on
control/handshake signal inputs such as CTS,
RTS, DTR and DSR can have damaging effects
on the integrity of a connection. The XRT4000
is equipped with lowpass filters on the input of
each of the receivers for the control and
handshake signals. These filters eliminate
glitches which are narrower than 10µs. The
user may disable these filters by setting
EN_FLTR to logic 0.
Rev. 1.00
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