SCAN25100TYA/NOPB National Semiconductor, SCAN25100TYA/NOPB Datasheet - Page 21

• 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

MDIO Serial Control Interface
The MDIO serial control interface allows communication be-
tween a station management controller and SCAN25100 de-
vices. MDIO and MDC pins are 3.3V LVTTL compliant, not
1.2V compatiable. It is software compatible with the station
management bus defined in IEEE 802.3ae-2002. The serial
control interface consists of two pins, the data clock MDC and
bidirectional data MDIO. MDC has a maximum clock rate of
2.5 MHz and no minimum limit. The MDIO is bidirectional and
can be shared by up to 32 physical devices.
The MDIO pin requires a pull-up resistor which, during IDLE
and turnaround, will pull MDIO high. The parallel equivalence
of the MDIO when shared with other devices should not be
less than 1.5 kΩ. Note that with many devices in parallel, the
internal pull-up resistors add in parallel. Signal quality on the
net should provide incident wave switching. It may be desir-
able to control the edge rate of MDC and MDIO from the
<1…1> is a sequence of 32 contiguous ones and is used as
preamble for synchronization purposes.
<PPPPP> is the PHY address of the device, defined by the
logic states of ADD[4:0]. The MSB bit is the first bit transmitted
or received. The PHY address is read at power-up or after a
RESET event.
<EEEEE> is the device (register) address. The MSB bit is the
first bit transmitted or received.
MDIO OPERATION
The MDIO interface is active when the SCAN25100 is pow-
ered up, REFCLK is present, and the SCAN25100 not being
reset through the RESETB pin. The MDIO bus returns the
following data:
•
•
•
•
The Start code is indicated by a <01> pattern. This assures
the MDIO line transitions from the default idle line state.
Mgmt Bus Protocol
Address
Write
Read
Read-Increment-Address
Correct PHY ADD, Correct DEV ADD — expected content
Incorrect PHY ADD, Correct DEV ADD — FFFF’h
Correct PHY ADD, Incorrect DEV ADD — 0000’h
RESETB = Low — FFFF’h
<Preamble><Start><OpCode><PHY addr><dev addr><turnaround><data><idle>
<1…1><00><00><PPPPP><EEEEE><10><AAAA AAAA AAAA AAAA><idle>
<1…1><00><01><PPPPP><EEEEE><10><DDDD DDDD DDDD DDDD><idle>
<1…1><00><11><PPPPP><EEEEE><Z0><DDDD DDDD DDDD DDDD><idle>
<1…1><00><10><PPPPP><EEEEE><Z0><DDDD DDDD DDDD DDDD><idle>
TABLE 15. 802.3ae MDIO Bus Protocol
21
station management controller to optimize signal quality de-
pending upon the trace net and any resulting stub lengths.
In order to initialize the MDIO interface, the station manage-
ment sends a sequence of 32 contiguous logic ones on MDIO
with MDC clocking. This preamble may be generated either
by driving MDIO high for 32 consecutive MDC clock cycles,
or by simply allowing the MDIO pull-up resistor to pull the
MDIO high for 32 MDC clock cycles. A preamble is required
for every operation (64-bit frames, do not suppress pream-
bles).
MDC is an a periodic signal. Its high or low duration is 160 ns
minimum and has no maximum limit. Its period is 400 ns min-
imum. MDC is not required to maintain a constant phase
relationship with TXCLK, SYSCLK, and REFCLK. The follow-
ing table shows the management frame structure in according
to IEEE 802.3ae.
<AAAA AAAA AAAA AAAA> is the 16-bit address field of the
register to be accessed. The first bit transmitted or received
is bit 15.
<DDDD DDDD DDDD DDDD> is the 16-bit data field. It is the
data to be written into the SCAN25100 when performing a
Write operation. During the Read or Read-Increment-Address
operation, it is the read-back data from the SCAN25100. The
first bit transmitted or received is bit 15.
Turnaround is defined as an idle bit time inserted between the
Register Address field and the Data field. To avoid contention
during a read transaction, no device shall actively drive the
MDIO signal during the first bit of the turnaround. The ad-
dressed SCAN25100 drives the MDIO with a zero for the
second bit if the turnaround and follows this with the required
data. Figure 7 shows the timing relationship between MDC
and MDIO as driven/received by the Station and the
SCAN25100 for a typical read register access.
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