DP83848VYB National Semiconductor, DP83848VYB Datasheet - Page 19

• Manufacturer Part Number: DP83848VYB
• Description: TRANSCEIVER, ENET PHY, 10/100, 48LQFP
• Manufacturer: National Semiconductor

Specifications of DP83848VYB

• Data Rate: 100Mbps
• No. Of Ports: 1
• Ethernet Type: IEEE 802.3u
• Supply Current: 92mA
• Supply Voltage Range: 3V To 3.6V
• Operating Temperature Range: -40°C To +105°C
• Digital Ic Case Style: LQFP
• No.: RoHS Compliant
• Interface Type: MII Serial, RMII
• Rohs Compliant: Yes
• Lead Free Status / Rohs Status: Not Compliant

3.4.3 Serial Management Preamble Suppression
The DP83848VYB supports a Preamble Suppression mode
as indicated by a one in bit 6 of the Basic Mode Status Reg-
ister (BMSR, address 01h.) If the station management entity
(i.e. MAC or other management controller) determines that all
PHYs in the system support Preamble Suppression by re-
turning a one in this bit, then the station management entity
need not generate preamble for each management transac-
tion.
The DP83848VYB requires a single initialization sequence of
32 bits of preamble following hardware/software reset. This
FIGURE 4. Typical MDC/MDIO Write Operation
FIGURE 3. Typical MDC/MDIO Read Operation
19
requirement is generally met by the mandatory pull-up resis-
tor on MDIO in conjunction with a continuous MDC, or the
management access made to determine whether Preamble
Suppression is supported.
While the DP83848VYB requires an initial preamble se-
quence of 32 bits for management initialization, it does not
require a full 32-bit sequence between each subsequent
transaction. A minimum of one idle bit between management
transactions is required as specified in the IEEE 802.3u spec-
ification.
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