ML6680CQ Micro Linear, ML6680CQ Datasheet - Page 9

• Manufacturer Part Number: ML6680CQ
• Description: Token Ring Copper-to-Fiber Converter
• Manufacturer: Micro Linear

Modes of Operation
Four configurations are possible with the ML6680,
as follows:
CONFIGURATION 1
Standard Media Converter:
This configuration is selected by tying KEYGEN to VCC.
There are always two fixed signal paths, one from TPINP and
TPINN to OPVCC and OPOUT, and another from OPINP
and OPINN to TPOUTP and TPOUTN. The generation of
the “Insertion Key” or “Bypass Key” is exclusively controlled
by the logic values at PHTM1 and PHTM2. The “Insertion
Key” is generated when both PHTM1 and PHTM2 go low,
and stay low for at least 26.5ms. If the “Insertion Key Echo”
is received within the following 100ms, the part goes to
the “Insert State” and the LED output INSERTED goes low.
During the generation of the “Insertion Key,” and while
waiting for the “Insertion Key Echo” the states of PHTM1
and PHTM2 do not have any effect. When the part is in
the “Insert State” and either PHTM1 or PHTM2 goes high,
the LED output INSERTED goes high, the part leaves the
“Insert State,” generates the “Bypass Key,” and starts
waiting for PHTM1 and PHTM2 to go low again.
CONFIGURATION 2
Concentrator Media Converter:
This configuration is selected by tying KEYGEN to ground.
There are always two fixed signal paths, one from TPINP and
TPINN to OPVCC and OPOUT, and another from OPINP
and OPINN to TPOUTP and TPOUTN. The part powers
on in the “Bypass State” where it neither applies phantom
current nor checks for a phantom wire fault. After
recognizing an “Insertion Key” at its fiber optic inputs, it
applies phantom power by providing current at PHTM1 and
PHTM2, goes to the “Phantom Wire Fault Check State,” and
starts waiting for a “Bypass Key.” At this state, the LED output
INSERTED stays low while no phantom wire fault is
detected. When the part is in the “Phantom Wire Fault Check
State” and a “Bypass Key” is recognized, the part leaves
this state, removes the phantom power, and starts waiting
for a “Insertion Key” again.
1.Standard Media Converter: Senses ISO/IEC8802-5
2.Concentrator Media Converter: Recognizes the ISO/
3.Lobe or Ring Out Port Media Converter: Recognizes
4.Ring In Port Media Converter: Generates ISO/
phantom power and generates ISO/IEC8802-5
fiberoptic insertion or bypass requests.
IEC8802-5 fiberoptic insertion or bypass requests and
drives the ISO/IEC8802-5 phantom circuits.
the ISO/IEC8802-5 fiberoptic insertion or bypass
requests.
IEC8802-5 fiberoptic insertion or bypass requests.
Modifies the internal signal paths depending on the
presence or absence of a fiberoptic link, and on the
reception of the ISO/IEC8802-5 “Insertion Key Echo.”
CONFIGURATION 3
Lobe or Ring Out Port Media Converter:
This configuration is selected by tying both KEYGEN and
TPINOK to ground. When the ML6680 is in the “Insert
State,” the signal paths are from TPINP and TPINN to
OPVCC and OPOUT, and from OPINP and OPINN to
TPOUTP and TPOUTN. Otherwise, the signal paths are
from TPINP and TPINN to TPOUTP and TPOUTN, and
from OPINP and OPINN to OPVCC and OPOUT. The part
powers on in the “Bypass State” and goes to the “Insert
State” after recognizing an “Insertion Key” at its fiber optic
inputs. It goes back to the “Bypass State” after recognizing
a “Bypass Key.” While it is at the “Insert State,” the LED
output INSERTED stays low.
CONFIGURATION 4
Ring In Port Media Converter:
This configuration is selected by tying KEYGEN to VCC
and TPINOK to ground. When the part is in the “Insert
State,” the signal paths are from TPINP and TPINN to
OPVCC and OPOUT, and from OPINP and OPINN to
TPOUTP and TPOUTN. Otherwise, the input at TPINP
and TPINN is routed to TPOUTP and TPOUTN, and also
to OPVCC and OPOUT. The “Insertion Key” is generated
when activity is detected at OPINP and OPINN for at least
26.5ms and, PHTM1 and PHTM2 stay low. If the
“Insertion Key Echo” is received within the following
100ms, the ML6680 goes to the “Insert State” and the LED
output INSERTED goes low. During the generation of the
“Insertion Key,” and while waiting for the “Insertion Key
Echo” the logic states of PHTM1 and PHTM2 do not have
any effect. When the part is in the “Insert State” and no
activity is detected at OPINP and OPINN for at least
26.5ms, or either PHTM1 or PHTM2 goes high, the LED
output INSERTED goes high, the part leaves the “Insert
State,” generates the “Bypass Key,” and starts waiting for
26.5ms of optical input activity again.
Low Frequency Signaling Mode
Some old implementations of discrete media converters,
use a non-standard protocol with frequencies between
1 and 10kHz. To facilitate the migration to the ML6680,
a specific operating mode is provided by grounding the
pin INSERTED. Pin KEYGEN should also be grounded to
prevent the generation of unwanted “Insertion” or “Bypass
Keys.” In this operating mode, the optical frequency
squelch circuitry is disabled and the time constant of the
amplitude squelch is significantly reduced.
For each edge of the low frequency optical input, the
ML6680 generates a pulse at the led output OPINOK.
It also generates a pulse at the TPOUTP output for each
rising edge and another at the TPOUTN output for
each falling edge.
ML6680
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