DM9095L View Datasheet(PDF) - Davicom Semiconductor, Inc.
Part Name
Description
Manufacturer
DM9095L Datasheet PDF : 21 Pages
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DM9095
Twisted-Pair Medium Attachment Unit
Function Description
Transmit Functions
The DM9095 receives transmit data from DO + /DO - and
transfers it to the TP network. The input must be
transformer-coupled to the AUI circuit. The receiver is able
to pass differential signals as small as 300mV peak and as
large as 1315mV. DC biasing is provided with internal
common-mode, the common-mode is set to nominal 2.5V.
An internal analog delay line is used to generate the pre-
distortion signals at DTPO + and DTPO -. The DTPO + /
DTPO - signal delays 50ns after TPO + / TPO -. A delay
lock loop, referenced to the crystal clock, is used to generate
the internal delay line. All TP output driver pins are driver
low as a result of any of the following: there is an AUI IDL
pulse of at least 200ns duration; the output driver is
jabbered; the link-integrity option is enabled and there is a
link failure; or an IDL pulse is not detected at the end of a
² packet and the input dose not exceed the detection
threshold of 500ns 100ns. When the driver detects that it
has finished sending an IDL pulse onto the TP, a timer of
not more than 500ns is started. While this timer is active,
activity on the DO + / DO - inputs is ignored.
Receive Functions
The TP receiver is connected to a band-limiting filter, whose
input is transformer-coupled to the twisted-pair TPI + / TPI -
pins. The receiver is able to resolve differential signals as
small as 350mV peak. Common-mode input voltage is
provided with internal common-mode, with the common-
mode set to nominal 2.5V. The receiver squelch circuit
prevents noise on the twisted-pair cable from falsely
triggering the receiver in the absence of true data. The
receiver will not be activated for signals at the buffer input
having a peak amplitude below 300mV, a continuous
frequency below 2 MHz, or a single cycle duration within the
pass band of the receive filter. This driver differentially
drives a current onto the load connected between the DI +
² ² and DI - pins. The current through the load results in an
output voltage between 0.6V and 1.2V, measured
differentially between the two pins. As in figure 4, it shows
the typical loading for DI + / DI - driver. When the driver
detects that it has finished sending an IDL pulse onto the
AUI, a timer of not more than 500ns is started. While this
timer is active, activity on the TPI + / TPI - inputs is ignored,
and the AUI driver discharges the current stored on the
inductive load.
Collision Functions
A collision state exists whenever there are valid inputs to the
DM9095 from the network and from the DTE
simultaneously and the device is not in a link-integrity failure
state. The DM9095 reports collisions to the AUI by sending
a 10 MHz signal over the CI + / CI - pair. The collision
report signal is output no more than 9 BT after the chip
detects a collision. If TPI + / TPI - become active while
there is activity on the DO + / DO - pair, the loopback data
² on TPI + / TPI - switches from transmit data to receive data
within 13 BT 3 BT. If a collision condition exits with TPI +
² / TPI - having gone idle while DO + / DO – are still active,
SQE continues for 7 BT 2 BT. If a collision condition
exits with DO + / DO – having gone idle while TPI + / TPI–
are still active, SQE may continue for up to 9 BT.
Jabber Functions
Jabber is a self-interrupt function that keeps a damaged
node from continously transmitting onto the network. The
chip contains a nominal window of 50ms, during which time
a normal data link frame can be transmitted. If a frame
length exceeds this duration, the jabber function inhibits
transmission and sends a collision signal on the CI + / CI –
pair. When activity on the DO + / DO – pair has ceased,
² the chip continues to present the CSO signal to the CI + /
CI – pair for 0.5s 50%. The transmission of link-integrity
pulses from the TP drivers is not inhibited when the
DM9095 is jabbed and the link integrity function is enabled.
SQE Test Functions
When the DO + / DO – pair has gone idle after a successful
transmission and the heartbeat function is enabled, the chip
presents the CSO signal to the CI + / CI – pair. After a
² successful transmission onto the network media, the chip
presents the CSO signal within 11 BT 5 BT of the end of
² activity on the DO + / DO – pair. The CSO signal is
presented for 10 BT 5 BT, after which the chip presents an
IDL on the CI + / CI – pair and returns to the idle state.
9
Final
Version: DM9095-DS-F02
August 21, 2000
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