78Q2120C Teridian Semiconductor Corp. (TDK Semiconductor), 78Q2120C Datasheet - Page 6

• Manufacturer Part Number: 78Q2120C
• Description: 10/100 Ethernet PHYS
• Manufacturer: Teridian Semiconductor Corp. (TDK Semiconductor)

PIN DESCRIPTION
LEGEND
MII (MEDIA INDEPENDENT INTERFACE)
© 2003 TDK Semiconductor Corporation, Proprietary and Confidential
TYPE
CIU
TX_CLK
TX_EN
TXD[3:0]
TX_ER
CRS
COL
RX_CLK
RX_DV
RXD[3:0]
CIS
CO
A
S
NAME
DESCRIPTION
Analog Pin
TTL-level Input w/ Pull-up
TTL-level Input w/ Schmitt Trigger
CMOS Output
Supply
32-29
19-22
PIN
27
28
26
34
33
24
23
TYPE
COZ
COZ
COZ
COZ
COZ
COZ
CI
CI
CI
DESCRIPTION
TRANSMIT CLOCK: TX_CLK is a continuous clock, which provides a timing
reference for the TX_EN, TX_ER and TXD[3:0] signals from the MAC. The
clock frequency is 25MHz in 100BASE-TX mode and 2.5MHz in 10BASE-T
mode. This pin is tristated in isolate mode and TXHIM mode.
TRANSMIT ENABLE: TX_EN is asserted by the MAC to indicate that valid
data for transmission is present on the TXD[3:0] pins.
TRANSMIT DATA: TXD[3:0] receives data from the MAC for transmission on
a nibble basis. This data is captured on the rising edge of TX_CLK when
TX_EN is high.
TRANSMIT ERROR: TX_ER is asserted high to request that an error code-
group be transmitted when TX_EN is high. In PCS bypass mode this pin
becomes the MSB of the transmit 5-bit code group.
CARRIER SENSE: When the 78Q2120C is not in repeater mode, CRS is high
whenever a non-idle condition exists on either the transmitter or the receiver.
In repeater mode, CRS is only active when a non-idle condition exists on the
receiver. This pin is tristated in isolate mode.
COLLISION: COL is asserted high when a collision has been detected on the
media. In 10BASE-T mode, COL is also used for the SQE test function. This
pin is tristated in isolate mode.
RECEIVE CLOCK: RX_CLK is a continuous clock, which provides a timing
reference to the MAC for the RX_DV, RX_ER and RXD[3:0] signals. The
clock frequency is 25MHz in 100BASE-TX mode, and 2.5MHz in 10BASE-T
mode. To reduce power consumption, in 100BASE-TX mode, the 78Q2120C
provides an optional mode, enabled through MR16.0, in which RX_CLK is
held inactive (low) when no receive data is detected. This pin is tristated in
isolate mode.
RECEIVE DATA VALID: RX_DV is asserted high to indicate that valid data is
present on the RXD[3:0] pins. In 100BASE-TX mode, it transitions high with
the first nibble of preamble and is pulled low when the last data nibble has
been received. In 10BASE-T mode, it transitions high when the start-of-frame
delimiter (SFD) is detected. This pin is tristated in isolate mode.
RECEIVE DATA: Received data is provided to the MAC via RXD[3:0]. These
pins are tristated in isolate mode.
- 6 -
TYPE
COZ
CID
CIO
CI
G
DESCRIPTION
TTL-level Input
TTL-level Input w/ Pull-down
TTL-compatible Bi-directional Pin
Tristate-able CMOS output
Ground
10/100BASE-TX Transceiver
78Q2120C
Rev_1.1