DS36C200M National Semiconductor, DS36C200M Datasheet - Page 7

• Manufacturer Part Number: DS36C200M
• Description: Dual High Speed Bi-Directional Differential Transceiver
• Manufacturer: National Semiconductor

Application Information
some ECL and PECL devices, but without the heavy static
I
tions for the driver are a tenfold improvement over other ex-
isting RS-422 drivers.
Fail-safe Feature:
The LVDS receiver is a high gain, high speed device that
amplifies a small differential signal (20mV) to CMOS logic
levels. Due to the high gain and tight threshold of the re-
ceiver, care should be taken to prevent noise from appearing
as a valid signal.
The receiver’s internal fail-safe circuitry is designed to
source/sink a small amount of current, providing fail-safe
protection (a stable known state of HIGH output voltage) for
floating, terminated or shorted receiver inputs.
1. Open Input Pins. The DS36C200 is a dual transceiver
>
CC
80% less current than similar PECL devices. AC specifica-
requirements of the ECL/PECL designs. LVDS requires
device, and if an application requires only one receiver,
the unused channel inputs should be left OPEN. Do not
tie the receiver inputs to ground or any other voltages.
The input is biased by internal high value pull up or pull
(Continued)
FIGURE 10. (A) Dedicated IEEE 1394 Link
(B) Full IEEE 1394 Compliant Link
7
2. Terminated Input. If the driver is disconnected (cable
3. Shorted Inputs. If a fault condition occurs that shorts
down resistors to set the output to a HIGH state. This in-
ternal circuitry will guarantee a HIGH, stable output state
for open inputs.
unplugged), or if the driver is in a TRI-STATE or
power-off condition, the receiver output will again be in a
HIGH state, even with the end of the cable 100
nation resistor across the input pins. The unplugged
cable can become a floating antenna which can pick up
noise. If the cable picks up more than 10mV of differen-
tial noise, the receiver may see the noise as a valid sig-
nal and switch. To insure that any noise is seen as
common-mode and not differential, a balanced intercon-
nect should be used. Twisted pair cable will offer better
balance than flat ribbon cable.
the receiver inputs together, thus resulting in a 0V differ-
ential input voltage, the receiver output will remain in a
HIGH state. Shorted input fail-safe is not supported
across the common-mode range of the device (GND to
2.4V). It is only supported with inputs shorted and no ex-
ternal common-mode voltage applied.
DS012621-14
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