VITESSE
Data Sheet
Features
• Serial Data Rates up to 2.5 Gb/s
• Parallel Data Rates up to 312.5 Mb/s
• ECL 100K Compatible Parallel Data I/Os
• Divide-by-8 Clock for Synchronization of
Parallel Data to Interfacing Chips
• SONET Frame Recovery Circuitry (VS8022)
• Compatible with STS-3 to STS-48
SONET Applications
VS8021/8022
2.5 Gbits/sec SONET Compatible
8-bit Mux/Demux Chipset
• Differential or Single-Ended Inputs and Outputs
• Low Power Dissipation: 2.3W (Typ. Per Chip)
• Standard ECL Power Supplies: VEE = -5.2 V,
VTT = -2.0 V
• Available in Commercial (0
°
to +70° C) or
Industrial (-40° to +85° C) Temperature Ranges
• Proven E/D Mode GaAs Technology
• 52-pin Leaded Ceramic Chip Carrier
Functional Description
The VS8021 and VS8022 are high speed SONET interface devices capable of handling serial data at rates
up to 2.5 Gbits/second. These products can be used for STS-3 through STS-48 SONET applications.
These products are fabricated in gallium arsenide using the Vitesse H-GaAs
™
E/D MESFET process which
achieves high speed and low power dissipation. These products are packaged in a ceramic 52-pin leaded
ceramic chip carrier.
VS8021
The VS8021 contains an 8:1 multiplexer and a self-positioning timer. The 8:1 multiplexer accepts 8 parallel
differential ECL data inputs (D1-D8, D1N-D8N) at rates up to 312.5 Mbits/sec and multiplexes them into a
serial differential bit stream output (DO, DON) at rates up to 2.5 Gbits/sec.
The internal timing of the VS8021 is built around the high speed clock (up to 2.5 GHz) delivered onto the
chip through a differential input (CLKI, CLKIN). This signal is subsequently echoed at the high speed differen-
tial output (CO, CON).
The parallel data inputs are clocked to on-chip input registers with an externally supplied differential ECL
input (BYCLK, BYCLKN) operating at the same rate as the data inputs. An internal byte clock, which is a
divide by 8 version of the high speed clock, is used to transfer the data to a set of buffer registers. This internal
byte clock is brought off chip at the ECL output CLK8, CLK8N.
Internal circuitry monitors the internal and external byte clocks and generates an ERR signal if a timing
violation is detected. This signal can be gated to the SYNC input which is edge sensitive high. An active SYNC
input allows the VS8021 timing to shift, positioning it properly against the external byte clock, CLK8, CLK8N.
When a CLK8 timing switch is made, normal data flow will be invalid for 1 byte.
There are two clock inputs, namely the CLKI and BYCLK, going into the VS8021. These two clocks serve
as timing references for different parts of the VS8021. The BYCLK is used to trigger the input registers for the
parallel data inputs, while the CLKI is used to trigger the high speed serial output register as well as some of the
timing circuitry for the parallel to serial conversion. Furthermore, in order to make this part easy to use, the user
is not required to assume a known phase relationship between CLKI and the BYCLK.
G52028-0 Rev. 4.0
®
VITESSE
Seiconductor Corporation
Page 1
VS8021/8022
VITESSE
Data Sheet
2.5 Gbits/sec SONET Compatible
8-bit Mux/Demux Chipset
An internal Phase Detector and Phase Adjust Circuit are used to facilitate the two asynchronous circuits to
work with each other. The Phase Detector and the Phase Adjust Circuit work together to adjust the internal
clock CLK8 to make sure the set up and hold conditions are met for the internal registers. CLK8 is derived from
CLKI and the RCLK is a non-phase varying byte clock output. The edge sensitive SYNC signal is simply the
control signal that enables the Phase Detector circuitry.
As a summary, the CLKI is the high speed clock input. The BYCLK is the external byte clock. The CLK8
is the internal byte clock derived from CLKI, phase-adjusted if SYNC is enabled. The RCLK is a non-phase-
adjusted divided-by-8 clock generated from CLKI. The phase of RCLK, RCLKN is not affected by the self-
adjusting circuitry, therefore it can be used as a system reference clock. RCLK, RCLKN can be used by the sys-
tem designer to generate BYCLK, BYCLKN. The self-positioning timer and RCLK, RCLKN allow for the cre-
ation of very tight parallel data timing for the VS8021.
Figure 1: VS8021 Block Diagram
Parallel
Data
Inputs
8
Buffer Register
Input Register
D1
D1N
8
8:1
Multiplexer
DO
DON
Serial Data Output
D8
D8N
CLK8
SYNC
BYCLK
BYCLKN
Phase
Adjust
CLK8N
Phase Adjustable
Byte Clock Output
Phase
Detecto
r
Byte Clock
Inputs
Timing
Generator
RCLK
RCLKN
CO
CON
ERR
Independent
Byte Clock Output
High Speed
Clock Inputs
CLKI
CLKIN
High Speed
Clock
Output
Page 2
®
VITESSE
Semiconductor Corporation
G52028-0 Rev. 4.0
VITESSE
Data Sheet
VS8022
VS8021/8022
2.5 Gbits/sec SONET Compatible
8-bit Mux/Demux Chipset
The VS8022 contains both a 1:8 demultiplexer and SONET frame recovery circuitry. The 1:8 demultiplexer
accepts a serial data input (
DI, DIN
) at rates up to 2.5 Gbits/second and converts it into 8 parallel differential ECL
data outputs (
D1-D8, D1N-D8N
) at rates up to 312.5 Mbits/sec. Valid parallel data outputs are indicated by the
divide by 8 differential clock outputs
BYCKO, BYCKON
.
The VS8022 also contains a SONET frame recovery circuit. The frame recovery circuits are enabled by a falling
edge on the
OOFN
ECL input when the
FDIS
input is low. Once enabled, the frame recovery circuit starts looking
for the SONET framing sequence. Once the frame is detected, the word boundary is realigned, a confirmation signal
is sent off-chip through the
FP
ECL output and the frame recovery circuits are disabled. While the frame aligner is
hunting for the frame,
BYCKO, BYCKON
and parallel data are invalid.
Figure 2: VS8022 Block Diagram
D1
D1N
Serial Data In
DI
DIN
1:8
Demultiplexer
Parallel
Data Outputs
D8
D8N
High Speed
Clock Inputs
CLKI
CLKIN
Timing
Generator
Frame Recovery Disable —
FDIS
Frame Recovery Clock —
OOFN
SONET
Frame
Detection &
Recovery
FP
— Frame Detection Signal
BYCKO
BYCKON
Byte Clock Out
Frame recovery circuits are disabled by frame detection (resulting in FP) or by a falling edge on the OOFN
input while FDIS is high.
G52028-0 Rev. 4.0
®
VITESSE
Seiconductor Corporation
Page 3
VS8021/8022
VITESSE
Data Sheet
2.5 Gbits/sec SONET Compatible
8-bit Mux/Demux Chipset
VS8021 Multiplexer AC Characteristics
(Over recommended operating conditions)
Parameter
t
C(1)
t
D
t
DSU
t
DH
t
CMD
t
BCLK8(2)
jitter(pk-to-pk)
Clock period
BYTE clock period (t
D
= t
C
x 8)
Parallel data set-up time
Data hold time
High speed clock output (CO, CON) timing, falling edge of
CO to muxed data output, (DO, DON) timing
Byte clock to CLK8 timing
CLKI, CLKIN to DO, DON (max-min), (HI to LO), same part,
same pin at constant conditions
Description
Min
400
3.2
0.6
1.4
220
0.5
-
Typ
-
-
-
-
-
1.0
<50
Max
-
-
-
-
350
1.5
-
Units
ps
ns
ns
ns
ps
ns
ps
Note: (1) The parts are guaranteed by design to operate from DC to a maximum frequency of 2.5 GHz.
(2) Required when SYNC not connected to ERR
Figure 3: VS8021 Multiplexer Waveforms
t
C
CLKI
(1)
, CLKIN
High speed differential clock input
t
D
BYCLK (BYCLKN)
Byte clock input
(2)
Phase adjustable
÷8
output
t
DSU
t
DH
t
BCLK8
VALID DATA(2)
t
CMD
(1)
CLK8
D1-D8, D1N-D8N
Parallel differential data inputs
VALID DATA(1)
CO, CON
High speed differential clock outputs
DO,DON
High speed differential data outputs
D01
D02
D03
D04
D05
D06
D07
D08
SYNC
CLK8 adjustment input
NOTES: (1) Negative edge is active edge.
(2) BYCLK/CLK8 timing required when SYNC not connected to ERR.
CLKI (CLKIN)
period x 8 =
BYCLK (BYCLKN)
period.
= Don't care.
Serialized Byte 1
Page 4
®
VITESSE
Semiconductor Corporation
G52028-0 Rev. 4.0
VITESSE
Data Sheet
VS8021/8022
2.5 Gbits/sec SONET Compatible
8-bit Mux/Demux Chipset
Figure 4: VS8022 Demultiplexer Waveforms
t
C
CLKI (CLKIN)
(1)
High speed differential clock input
t
OOFNPW
t
OOFN
SONET STS-3 Framing Sequence
DATA
DATA
DATA
DATA
DATA
OOFN
Frame recovery clock input
DI (DIN)
High speed serial data inputs
A1
A1
A1
A2
A2
A2
t
D
BYCKO (BYCKON)
Byte clock output
BYCKO
Resynch
t
BD
Valid
Valid
Valid
Valid
Valid
Valid
Valid
Valid
Data
Data
Data
Data
Data
Data
Data
Data
Valid
Valid
Valid
Valid
Valid
Valid
Valid
Valid
Data
Data
Data
Data
Data
Data
Data
Data
D1 (D1N)
D2 (D2N)
Demultiplexed
Parallel Data
Outputs
D3 (D3N)
D4 (D4N)
D5 (D5N)
D6 (D6N)
D7 (D7N)
D8 (D8N)
Parallel Data
(2)
Output Summary
FP
Frame detection confirm output
A1
A1
t
DFP
A2
A2
A2
t
PFP
Data
Data
Data
Data
NOTES:
1) Negative edge is active edge.
2) The parallel data outputs only begin showing valid data after the last A2 of the SONET framing sequence. The example
waveforms shown above use an STS-3 framing sequence for convenience, thus valid data is output after the third
A2 in the sequence.
= Don't care.
G52028-0 Rev. 4.0
®
VITESSE
Seiconductor Corporation
Page 5
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