SCAN25100TYA/NOPB National Semiconductor, SCAN25100TYA/NOPB Datasheet - Page 13

• Manufacturer Part Number: SCAN25100TYA/NOPB
• Description: IC SERIAL/DESERIAL CPRI 100-TQFP
• Manufacturer: National Semiconductor
• Series: SCANr

Specifications of SCAN25100TYA/NOPB

• Function: Serializer/Deserializer
• Data Rate: 2.5Gbps
• Input Type: LVTTL/LVCMOS
• Output Type: LVTTL, LVCMOS
• Number Of Inputs: 10
• Number Of Outputs: 10
• Voltage - Supply: 1.7 V ~ 1.9 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 100-TQFP Exposed Pad, 100-eTQFP, 100-HTQFP, 100-VQFP
• Operating Temperature (min): -40C
• Operating Temperature Classification: Industrial
• Operating Temperature (max): 85C
• Package Type: TQFP EP
• Rad Hardened: No
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: SCAN25100TYA

Functional Description
POWER UP AND LINK SYNCHRONIZATION
An internal power on reset (POR) circuit disables the trans-
mitter output and sets receiver ROUT[9:0], LOS, LOCKB, and
CDET in static high state for approximately 150 ms (150ms is
based on an internal counter monitoring the 30.72 MHz Ref-
CLK) to allow external clock sources to stabilize. A special
power up sequence is not required, but a monotonic power
ramp will ensure the SCAN25100 attains the proper initial
state when stable supply levels within the recommended
range are achieved . Once the transmitter powers up and TX-
CLK becomes active, the transmitter starts sending valid
data. Once the receiver is powered up and REFCLK exists,
the receiver is ready to receive data. When comma alignment
is enabled (CALIGN_EN = 1), the receiver searches for a valid
comma in the incoming stream. When a comma is detected,
the receiver performs code group (comma) alignment and
presents data on ROUT.
POWER DOWN
When the transmitter is powered down by pulling pin TXP-
WDNB down, DOUT is put into a high impedance state. When
the receiver is powered down by pulling RXPWDNB down,
ROUT[9:0], LOS, LOCKB, CDET, RXCLK, and SYSCLK are
high impedance. The MDC/MDIO signal pins are not powered
down when TXPWDNB and/or RXPWDNB are low.
FIGURE 1. Power Up State Diagram
13
To ensure the parallel bus FIFO read/write pointer distance is
half of the total FIFO depth, the following procedure should
be followed (e.g., after reset or comma (re)alignment):
1.
2.
3.
4.
Resetting the SCAN25100
The SCAN25100 has a rich set of hardware and software re-
set functions. When performing hardware pin resets, TXP-
WDNB and RXPWDNB pins or the RESETB pin must be held
low for at least 1 us.
Power up SCAN25100 while holding TXCLK and RXCLK
(in read mode) input clocks static low or high. The
SCAN25100 will hold both transmitter and receiver
FIFO’s in reset until the TXCLK and RXCLK start
toggling.
Wait for all clock sources to become synchronous and
stable based on the CPRI timing specification.
Toggle TXCLK and RXCLK input clocks to latch data into
and out of the parallel DIN/ROUT buses.
If at any time the clock requires a resynchronization, such
as switching 30.72 MHz system clock. Holding TXCLK
and RXCLK (in read mode) static high or low resets the
SCAN25100 internal FIFO pointers.
20183403
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