LXD971L Intel, LXD971L Datasheet - Page 7

• Manufacturer Part Number: LXD971L
• Manufacturer: Intel

Specifications of LXD971L

• Lead Free Status / RoHS Status: Not Compliant

LXT38x LIU
Application Note
249464, Revision 2.0
10 August 2007
2.1.2
1+1 Protection without Relays Using Cortina Systems
Some features available in these devices ease the development of redundant protection
systems:
The driver tristate feature allows the designer to connect the redundant driver output in
parallel with the primary driver when one of them is tristated. Similarly, because the
receiver impedance is very high, two receivers can be connected in parallel.
The following sections will describe the “standard” HPS 3-board solution, an HPS solution
with one of the boards unpowered, a 2-board HPS solution and a hot swappable HPS
solution.
All of the circuits described in this Application Note were built and tested using the
evaluation boards for the LXT38x LIU.
Design Considerations
This section contains some design considerations to account for in all LIU designs.
• LXT384 LIU: Octal T1/E1/J1 LIU with digital jitter attenuation. Both hardware and
• LXT386 LIU: Quad T1/E1/J1 LIU with digital jitter attenuation. Both hardware and
• LXT388 LIU: Dual T1/E1/J1 LIU with dual digital jitter attenuation. Both hardware and
• Output tristating by freezing the TCLK signal
• Fast output tristating by using the OE pin
• Software controllable output driver tristate by using the OE register
• High receiver input impedance of 70 kΩ typ
• Constant delay jitter attenuator (LXT384/6/8 LIUs only)
• Minimize trace/cable lengths. Long cable lengths may reduce the output amplitude.
• Minimize parasitic capacitance. High parasitic capacitance will affect both the pulse
• Surge immunity. The protection elements recommended in
• Place the TVS close to the connector. Surge protection should be placed as close
• Include TVS protection in the power supply. The protection diodes (D1 – D8) will
software modes are available.
software modes are available.
software modes are available.
In the experiments conducted, the cable connecting the primary, back-up and LIC
boards did not exceed 25 cm. If longer cables are to be used, the transmit series
resistors (R10 – R13) may need to be reduced to compensate for the loss in
amplitude.
shape and the return loss performance. The protection components chosen for this
Application Note have a very low capacitance at the nominal operating voltage. Note
that long cable lengths also add to the total parasitic capacitance. In some cases, the
transmit capacitor (C4) may have to be adjusted to optimize pulse shape and return
loss performance.
sufficient for compliance with IEC 61000-4-5 (EN-6100-4-5) with up to 24 A peak
current on a 1.2/50 μsec surge. If additional protection is required, a different line TVS
may be necessary.
as possible the source of the disturbance, that is, the connector.
couple current to the power supply (TVcc) in the event of a lightning surge. To protect
other circuits on the board, a 3.3 V TVS should be included in the power supply. A TVS
suitable for this application is the SMLVT 3V3. A similar device for 5 V should be
selected if TVcc is 5 V .
®
LXT380/1/4/6/8 Hitless Protection Switching
Figure 2
and
2.1 Architecture
Figure 3
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are