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Número de pieza | DS25BR400 | |
Descripción | Quad Transceiver | |
Fabricantes | National Semiconductor | |
Logotipo | ||
Hay una vista previa y un enlace de descarga de DS25BR400 (archivo pdf) en la parte inferior de esta página. Total 12 Páginas | ||
No Preview Available ! May 2006
DS25BR400
Quad Transceiver with Input Equalization and Output
De-Emphasis
General Description
The DS25BR400 is a quad 250 Mbps – 2.5 Gbps CML
transceiver, or 8-channel buffer, for use in XAUI Fibre Chan-
nel backplane and cable applications. With operation down
to 250 Mbps, the DS25BR400 can be used in applications
requiring both low and high frequency data rates. Each input
stage has a fixed equalizer to reduce ISI distortion from
board traces. The equalizers are grouped in fours and are
enabled through two control pins. These control pins provide
customers flexibility in XAUI applications where ISI distortion
may vary from one direction to another. All output drivers
have four selectable steps of de-emphasis to compensate
against transmission loss across long FR4 backplanes. The
de-emphasis blocks are also grouped in fours. In addition,
the DS25BR400 also has loopback control capability on four
channels. All CML drivers and receivers are internally termi-
nated with 50Ω pull-up resistors.
Features
n Quad 2.5 Gbps Transceiver or 8-Channel CML Serial
Buffer
n 250 Mbps – 2.5 Gbps Fully Differential Data Paths
n Optional Fixed Input Equalization
n Selectable Output De-emphasis
n Individual Loopback Controls
n On-chip Termination
n +3.3V supply
n Low Power, 1.3 Watts MAX
n Lead-less eLLP-60 pin package
(9mmx9mmx0.8mm, 0.4mm pitch)
n −40˚C to +85˚C Industrial Temperature Range
n 6 kV ESD Rating, HBM
Functional Block Diagram
© 2006 National Semiconductor Corporation DS201942
20194201
www.national.com
1 page Functional Description
TABLE 1. Logic Table for Loopback Controls
LB0
0
1 (default)
LB1
0
1 (default)
LB2
0
1 (default)
LB3
0
1 (default)
Loopback Function
Enable loopback from IB_0± to OA_0±.
Normal mode. Loopback disabled.
Loopback Function
Enable loopback from IB_1± to OA_1±.
Normal mode. Loopback disabled.
Loopback Function
Enable loopback from IB_2± to OA_2±.
Normal mode. Loopback disabled.
Loopback Function
Enable loopback from IB_3± to OA_3±.
Normal mode. Loopback disabled.
PreA_[1:0]
00
01
10
1 1 (Default)
PreB_[1:0]
00
01
10
1 1 (Default)
TABLE 2. De-Emphasis Controls
Default VOD Level in mVPP
(VODB)
1200
1200
1200
1200
Default VOD Level in mVPP
(VODB)
1200
1200
1200
1200
De-Emphasis Level in mVPP
(VODPE)
1200
850
600
426
De-Emphasis Level in mVPP
(VODPE)
1200
850
600
426
De-Emphasis in dB
(VODPE/VODB)
0
−3
−6
−9
De-Emphasis in dB
(VODPE/VODB)
0
−3
−6
−9
De-emphasis is the primary signal conditioning function for
use in compensating against backplane transmission loss.
The DS25BR400 provides four steps of de-emphasis rang-
ing from 0, −3, −6 and −9 dB, user-selectable dependent on
the loss profile of the backplane. Figure 1 shows a driver
de-emphasis waveform. The de-emphasis duration is nomi-
nal 188 ps, corresponding to 0.75 bit-width at 2.5 Gbps. The
de-emphasis levels of switch-side and line-side can be indi-
vidually programmed.
5 www.national.com
5 Page Timing Diagrams (Continued)
FIGURE 6. AC Test Circuit
20194234
11 www.national.com
11 Page |
Páginas | Total 12 Páginas | |
PDF Descargar | [ Datasheet DS25BR400.PDF ] |
Número de pieza | Descripción | Fabricantes |
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