CYP15G0201DXB_05 Datasheet, PDF (17/46 Pages) Cypress Semiconductor – Dual-channel HOTLink II™ Transceiver

CYP15G0201DXB
CYV15G0201DXB
CYW15G0201DXB
generate a bit-rate clock for use by the Transmit Shifter. It also
provides a character-rate clock used by the transmit paths.
The clock multiplier PLL can accept a REFCLK input between
10 MHz and 150 MHz (19.5 MHz and 154 MHz for
CYW15G0201DXB), however, this clock range is limited by
the operating mode of the CYP(V)(W)15G0201DXB clock
multiplier (controlled by TXRATE) and by the level on the
SPDSEL input.
SPDSEL is a 3-level select^[4] (ternary) input that selects one
of three operating ranges for the serial data outputs and inputs.
The operating serial signaling-rate and allowable range of
REFCLK frequencies are listed in Table 10.
Table 10. Operating Speed Settings
SPDSEL
LOW
TXRATE
1
0
REFCLK
Frequency
(MHz)
Reserved
19.5–40
Signaling
Rate (MBaud)
195–400
signal of at least VI_DIFF > 100 mV, or 200 mV peak-to-peak
differential. Each Line Receiver can be DC- or AC-coupled to
+3.3V powered fiber-optic interface modules (any ECL/PECL
logic family, not limited to 100K PECL) or AC-coupled to +5V
powered optical modules. The common-mode tolerance of
these line receivers accommodates a wide range of signal
termination voltages. Each receiver provides internal
DC-restoration, to the center of the receiver’s common mode
range, for AC-coupled signals.
The local loopback input (LPEN) allows the serial transmit data
outputs to be routed internally back to the Clock and Data
Recovery circuit associated with each channel. When
configured for local loopback, all transmit serial driver outputs
are forced to output a differential logic-1. This prevents local
diagnostic patterns from being broadcast to attached remote
receivers.
Signal Detect/Link Fault
Each selected Line Receiver (i.e., that routed to the Clock and
Data Recovery PLL) is simultaneously monitored for
MID (Open)
1
0
HIGH
1
0
20–40
40–80
40–75
80–150
400–800
800–1500
(800–1540 for
CYW15G0201
DXB)
When TXRATE = HIGH (Half-rate REFCLK), TXCKSEL =
HIGH or MID (TXCLKx or TXCLKA selected to clock input
register) is an invalid mode of operation.
• analog amplitude above limit specified by SDASEL
• transition density greater than specified limit
• range controller reports the received data stream within
normal frequency range (±1500 ppm)^[11]
• receive channel enabled
All of these conditions must be valid for the Signal Detect block
to indicate a valid signal is present. This status is presented on
the LFIx (Link Fault Indicator) output associated with each
receive channel, which changes synchronous to the selected
receive interface clock.
The REFCLK± input is a differential input with each input inter- _{Table 11. Analog Amplitude Detect Valid Signal Levels}^[12]
nally biased to 1.4V. If the REFCLK+ input is connected to a
TTL, LVTTL, or LVCMOS clock source, the input signal is
SDASEL Typical signal with peak amplitudes above
recognized when it passes through the internally biased _LOW
140 mV p-p differential
reference point.
MID (Open) 280 mV p-p differential
When both the REFCLK+ and REFCLK– inputs are
connected, the clock source must be a differential clock. This
HIGH
420 mV p-p differential
can be either a differential LVPECL clock that is DC-or
AC-coupled, or a differential LVTTL or LVCMOS clock.
Analog Amplitude
By connecting the REFCLK– input to an external voltage
source or resistive voltage divider, it is possible to adjust the
reference point of the REFCLK+ input for alternate logic levels.
When doing so it is necessary to ensure that the 0V-differential
crossing point remains within the parametric range supported
by the input.
While the majority of these signal monitors are based on fixed
constants, the analog amplitude level detection is adjustable
to allow operation with highly attenuated signals, or in
high-noise environments. This adjustment is made through the
SDASEL signal, a 3-level select^[4] input, which sets the trip
point for the detection of a valid signal at one of three levels,
as listed in Table 11. This control input effects the analog
CYP(V)(W)15G0201DXB Receive Data Path
monitors for all receive channels.
The Analog Signal Detect monitors are active for the Line
Serial Line Receivers
Receiver, selected by the associated INSELx input. When
Two differential Line Receivers, INx1± and INx2±, are
available on each channel for accepting serial data streams.
The active Serial Line Receiver on a channel is selected using
the associated INSELx input. The Serial Line Receiver inputs
are differential, and can accommodate wire interconnect and
filtering losses or transmission line attenuation greater than
configured for local loopback (LPEN = HIGH), no line
receivers are selected, and the LFIx output for each channel
reports only the receive VCO frequency out-of-range and
transition density status of the associated transmit signal.
When local loopback is active, the Analog Signal Detect
Monitors are disabled.
16 dB. For normal operation, these inputs should receive a
11. REFCLK has no phase or frequency relationship with the recovered clock(s) and only acts as a centering reference to reduce clock synchronization time. REFCLK
must be within ±1500 ppm (±0.15%) of the remote transmitter’s PLL reference (REFCLK) frequency. Although transmitting to a HOTLink II receiver necessitates
the frequency difference between the transmitter and receiver reference clocks to be within ±1500 ppm, the stability of the crystal needs to be within the limits
specified by the appropriate standard when transmitting to a remote receiver that is compliant to that standard. For example, to be IEEE 802.3z Gigabit Ethernet
compliant, the frequency stability of the crystal needs to be within ±100PPM
12. The peak amplitudes listed in this table are for typical waveforms that have generally 3–4 transitions for every ten bits. In a worse case environment the signals
may have a sign-wave appearance (highest transition density with repeating 0101...). Signal peak amplitudes levels within this environment type could increase
the values in the table above by approximately 100 mV.
Document #: 38-02058 Rev. *H
Page 17 of 46