MAX9205/MAX9207
10-Bit Bus LVDS Serializers
6
Maxim Integrated
Initialization Mode
When V
CC
is applied, the outputs are held in high
impedance and internal circuitry is disabled by on-chip
power-on-reset circuitry. When the supply voltage
reaches 2.35V, the PLL starts to lock to a local refer-
ence clock (16MHz to 40MHz for MAX9205 and 40MHz
to 66MHz for MAX9207). The reference clock, TCLK, is
provided by the system. A serializer locks within 2049
cycles of TCLK. Once locked, a serializer is ready to
send data or SYNC patterns depending on the levels of
SYNC 1 and SYNC 2.
Synchronization Mode
To rapidly synchronize with a deserializer, SYNC pat-
terns can be sent. A SYNC pattern is six consecutive
ones followed by six consecutive zeros repeating every
TCLK period. When one or both SYNC inputs are
asserted high for at least six cycles of TCLK, the serial-
izer will initiate the transmission of 1024 SYNC patterns.
The serializer will continue to send SYNC patterns if
either of the SYNC input pins remains high. Toggling
one SYNC input with the other SYNC input low before
1024 SYNC patterns are output does not interrupt the
output of the 1024 SYNC patterns.
Data Transmission Mode
After initialization, both SYNC input pins must be set
low by users or through a control signal from the dese-
rializer before data transmission begins. Provided that
SYNC inputs are low, input data at IN0–9 are clocked
into the serializer by the TCLK input. Setting TCLK_R/F
high selects the rising edge of TCLK for data strobe
and low selects the falling edge. If either of the SYNC
inputs goes high for six TCLK cycles at any time during
data transmission, the data at IN0–9 are ignored and
SYNC patterns are sent for at least 1024 TCLK cycles.
A start bit high and a stop bit low frame the 10-bit data
and function as the embedded clock edge in the serial
data stream. The serial rate is the TCLK frequency
times the data and appended bits. For example, if
TCLK is 40MHz, the serial rate is 40 x 12 (10 + 2 bits) =
480Mbps. Since only 10 bits are from input data, the
payload rate is 40 x 10 = 400Mbps.
Power-Down
Power-down mode is entered when the PWRDN pin is
driven low. In power-down mode, the PLL of the serial-
izer is stopped and the outputs (OUT+ and OUT-) are
in high impedance, disabling drive current and also
reducing supply current. When PWRDN is driven high,
the serializer must reinitialize and resynchronize before
data can be transferred. On power-up, in order for the
MAX9205/MAX9207 to initialize correctly, PWRDN should
remain below 0.7V until PCLK is stable and all power sup-
plies are within specification.
High-Impedance State
The serializer output pins (OUT+ and OUT-) are held in
high impedance when the supply voltage is first
applied and while the PLL is locking to the local refer-
ence clock. Setting EN or PWRDN low puts the device
in high impedance. After initialization, EN functions
asynchronously. For example, the serializer output can
be put into high impedance while SYNC patterns are
being sent without affecting the internal timing of the
SYNC pattern generation. However, if the serializer
goes into high impedance, a deserializer loses PLL
lock and needs to resynchronize before data transfer
can resume.
Table 1. Input /Output Function Table
Synchronization Mode. SYNC patterns of six 1s and six 0s are
transmitted every TCLK cycle for at least 1024 TCLK cycles.
Data at IN0–9 are ignored.
Data Transmission Mode. IN0–9 and 2 frame bits are
transmitted every TCLK cycle.
Output in high-impedance.
