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Part: ML6680
Category:
Communication
-> Network
-> HDLC/Frame Relay/Token-Ring
Description: Token Ring Copper-to-fiber Converter
Company: Micro Linear
Datasheet: Download ML6680 datasheet File size : 123 kB
Request For quote: Find where to buy ML6680
Datasheet text preview:
January 1997
ML6680 Token Ring Copper-to-Fiber Converter
GENERAL DESCRIPTION
The ML6680 is a single-chip conversion between Token Ring ISO/IEC8802-5 copper-based media and Token Ring ISO/IEC8802-5 fiber-based media. The ML6680 fiber-optic interface contains a data quantizer, circuitry for fiber optic key signal generation and recognition, pin-selectable signal switching, and current driven transmitter outputs. The ML6680 copper interface consists of a twisted pair line equalizer, receive squelch circuit, pin selectable phantom wire fault detection and signal switching, and a transmit driver. This section supports the ISO/IEC8802-5 standard requirements. The ML6680 provides an optional PECL compatible interface. The ML6680 may be configured to one of four modes: 1. 2. 3. 4. Standard Media Converter Concentrator Media Converter Lobe or Ring Out Port Media Converter Ring In Port Media Converter
FEATURES
Single-chip copper-to-fiber converter for Token Ring 16Mbps and 4Mbps data rates with the same external components s Four modes of operation covering a wide variety of applications s Full duplex operation s Highly stable data quantizer with 55dB input dynamic range
s s
Current driven fiber optic LED driver for accurate launch power s Current driven output for low RFI noise and low jitter s Capable of driving 100 UTP or 150 STP s Pin selectable phantom wire fault detection and signal switching
s
BLOCK DIAGRAM
EQA TPINP TPINN TWISTED PAIR EQUALIZER D LED RIVER EQB RTSETOP OPVCC OPOUT
TPINOK
TWISTED PAIR RECEIVE SQUELCH
SIM NAL G UX
FIBER OPTIC RECEIVE SQUELCH
OPINOK
RTSETTP TPOUTP TPOUTN TWISTED PAIR DRIVER FIBER OPTIC QUANTIZER OPINP OPINN VDC PHTM1 PHTM2 PHANTOM D RIVER CONTROL L OGIC BIAS
XTAL1 O CRYSTAL SCILLATOR XTAL2
KEYGEN
INSERTED
1
ML6680
PIN CONFIGURATION
ML6680 28-Pin PLCC (Q28)
XTAL1 Q AL2 T OVCC
27
3 T PINP T P PINN PHTM1 G TM2 H T ND2 6 5 7 8 9 1 10 14 12
2
X CC2
VQA
EQB
1
28
26 25 24 23 22 21 10 9
PINP
Q OPINN V GND K DC GEYGEN OND1 OPGND POUT
T POUTP POUTN
13 14
15
16
17
18
NSERTED R
O SETOP T
R PINOK T
OINOK P
TSETTP V
CC1
2
I
TOP VIEW
PVCC
ML6680
PIN DESCRIPTION
PIN# NAME FUNCTION PIN# NAME FUNCTION
1, 28 XTAL1, XTAL2
Crystal inputs. A 32.768kHz watch crystal connected between these pins provides timing for the fiber optic insertion key signal. An external clock can be used to drive XTAL1 while grounding XTAL2. The frequency of the external clock should be between 32.7kHz and 34.5kHz. Positive 5V power supply.
13
RTSETTP
Twisted pair transmit level set resistor input. A precision resistor between RTSETTP and VCC sets the amplitude of the TPOUTP/N output. Positive 5V power supply.
14 15
VCC1
2 3, 4
VCC2
EQA, EQB Equalizer network pins. An external combination of two resistors and a capacitor connected at EQA and EQB sets up the on-chip twisted pair receive equalizer. Receive twisted pair inputs. This differential input pair receives differential Manchester signals from the coupling transformer (or PECL compatible levels). Phantom drive/sense inputs/outputs. In configuration 1, these pins are TTL inputs from two external opto isolators. They are low when phantom power is present and high when phantom power is removed. These pins provide the phantom drive current and are used to check for a wire fault on the phantom circuits when it is required in configuration 2. In configuration 3, these pins are don't cares. In configuration 4, these pins are low for normal operation, or any or both of them is high to force the ML6680 into the "Bypass State." Ground.
5, 6 TPINP/N
INSERTED Insertion indicator. It is an active low, open collector LED driver. In configurations 1, 3 and 4 this output goes low when the ML6680 is in the "Insert State." In configuration 2 this output goes low when the ML6680 is in the "Insert State" and no wire fault is detected. This input is tied to ground to disable the frequency squelch, and to reduce the time constant of the amplitude squelch of the optical input. RTSETOP A precision resistor between RTSETOP and VCC sets the amplitude of the OPOUT output. Valid fiber optic input signal indicator. It is an active low, open collector LED driver. This output goes low when the signal at OPINP/N meets frequency and amplitude squelch limit for received signals at TPINP/N. Positive 5V power supply for fiber optic LED driver. Fiber optic LED driver output. The fiber optic LED connects between this pin and OPVCC. Ground for the fiber optic LED driver. Ground. Key generation select CMOS input. This input is low for configurations 2 and 3 of the general description, and is high for configurations 1 and 4. Offset correction time constant capacitor input. An external capacitor between this pin and QGND determines the time constant of the internal offset correction circuit for the fiber optic quantizer. Quantizer 's ground. Receive fiber inputs. This pair of inputs receive differential Manchester signals from the fiber optic receiver/preamp and present them to the on-chip fiber optic quantizer. These inputs should be capacitively coupled to the input source. The input resistance is approximately 1.3k. Quantizer 's positive 5V power supply.
16
7, 8 PHTM1/2
17
OPINOK
18 19
OPVCC OPOUT
20 21 22
OPGND GND1 KEYGEN
9
GND2
10, 11 TPOUTP/N Transmit twisted pair outputs. This differential current output pair drives differential Manchester signals into the network coupling transformer and transmit filter. Output edge rates are controlled to allow use of a simpler filter than would otherwise be required. These outputs can be PECL compatible with an external resistor network. 12 TPINOK Valid twisted pair input signal indicator. It is an active low, open collector LED driver. This output goes low when the signal at TPINP/N meets frequency and amplitude squelch requirements. This input is tied to ground for configurations 3 and 4 to enable signal path switching.
23
VDC
24
QGND
26, 25 OPINP/N
27
QVCC
3
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