July 1999
ML6674
ATM 155Mbps UTP Transceiver
1
GENERAL DESCRIPTION
The ML6674 is a complete monolithic transceiver for
155Mbps NRZ encoded data transmission over category
5 unshielded twisted pair (UTP) and shielded twisted pair
(STP) cables. The ML6674 is compliant with the ATM
155Mbps Twisted Pair Specification. The ML6674 includes
the baseline restoration function and adaptive
equalization which will accurately compensate for line
losses exceeding 100m of UTP.
The ML6674 receive section consists of an equalizing
filter with a feedback loop for controlling effective line
compensation. The feedback loop contains a filter and
detection block for determining the proper control signal.
An ECL 100K compatible buffer at the output interfaces
directly with ATM physical interface chips.
The ML6674 transmit section accepts ECL 100K
compatible NRZ inputs.
FEATURES
s
Complies with ATM Forum 155Mbps twisted pair
specification
s
Integrated baseline wander correction circuit
s
Integrated adaptive equalization
s
Transmitter can be externally turned off
(high impedence) for true quiet line
s
Operates over 100 meters of STP or category 5 UTP
Twisted Pair Cable
s
32-pin PLCC and TQFP
BLOCK DIAGRAM
LINK
STATUS
ADAPTIVE
CONTROL
ADAPTIVE
EQUALIZER
ADAPTIVE
CONTROL REFERENCE
CMREF
RVCCD
RVCCA
RRSET
RRSET2
RRSET1
RGND
TGNDD
TGNDA
RXOUT
RXOUT+
SD
SD+
TXIN
TXIN+
TPOUT
TPOUT+
TPIN+
TPIN
LPBK
TXOFF
TVCCA
TVCCD
RTSET
RTSET1
RTSET2
MUX
ML6674
2
PIN CONFIGURATION
NAME
FUNCTION
TX
IN
+, TX
IN
These differential ECL100K compatible
inputs receive NRZ data from the PHY
for transmission.
TPOUT+,
Outputs from the NRZ buffer drive
TPOUT
these differential current outputs. The
transmitter filter/transformer module
connects the media to these pins.
LPBK
This TTL input enables transmitter-
Receiver loopback internally when
asserted low.
TXOFF
This TTL input forces the NRZ driver to
a high impedence state when asserted
low and shuts off transmit bias currrent.
RTSET1,
An external 1% resistor connected
RTSET2
between these pins controls the
transmitter output current amplitude.
I
OUT
= 32 x 1.25V/RTSET
TVCCA,
Separate analog and digital
TVCCD
transmitter power supply pins help to
isolate sensitive circuitry from noise
generating digital functions. Both
supplies are nominally +5 volts.
TGNDA,
Analog and digital transmitter grounds
TGNDD
provide separate return paths for clean
and noisy signals.
PIN DESCRIPTION
NAME
FUNCTION
SD+, SD
These differential ECL100K
compatible outputs indicate the
presence of a data signal with an
amplitude exceeding a preset
threshold.
TPIN+, TPIN
NRZ encoded data from the
receiver filter/transformer module
enters the Receiver through these
pins.
RXOUT+,
Differential ECL100K compatible
RXOUT
outputs provide NRZ encoded data
to the PHY.
RRSET1,
Internal time constants controlling
RRSET2
the equalizer's transfer function
are set by an external resistor
connected across these pins.
CMREF
This pin provides a DC common
mode reference point for the
receiver inputs.
RVCCA,
Analog and digital supply pins are
RVCCD
separated to isolate clean and
noisy circuit functions. Both
supplies are nominally +5 volts.
RGND
Receiver ground.
ML6674
32-Pin PCC (Q32)
ML6674
32-Pin TQFP (H32-7)
5
6
7
8
9
10
11
12
13
29
28
27
26
25
24
23
22
21
14 15 16 17 18 19 20
4
3
2
1
32 31 30
RXOUT+
RVCCD
SD
SD+
N/C
TGNDD
LPBK
TXOFF
N/C
RRSET1
RRSET2
N/C
N/C
RGND
N/C
N/C
TVCCA
TGNDA
TXIN+
TXIN
TVCCD
RTSET1
RTSET2
TPOUT+
TPOUT
RXOUT
RVCCA
N/C
N/C
CMREF
TPIN+
TPIN
1
2
3
4
5
6
7
8
24
23
22
21
20
19
18
17
9
10
11
12
13
14
15
16
32
31
30
29
28
27
26
25
TPOUT
TPOUT+
RTSET2
RTSET1
TVCCD
TXIN
TXIN+
N/C
RRSET1
TPIN
TPIN+
CMREF
N/C
N/C
RVCCA
RXOUT
RXOUT+
RVCCD
SD
SD+
N/C
TGNDD
LPBK
TXOFF
RRSET2
N/C
N/C
RGND
N/C
N/C
TVCCA
TGNDA
ML6674
3
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, T
A
= T
MIN
to T
MAX
, VCC = 5V 5%, RTSET = 2.0k. (Note 1)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
DC Characteristics
Supply Current
RVCCD
74
mA
RVCCA
65
mA
TVCCD
14
mA
TVCCA
6
mA
RVCCD + RVCCA + TVCCD + TVCCA
185
mA
TTL Inputs (TXOFF, LPBK)
V
IL
Input Low Voltage
0.8
V
V
IH
Input High Voltage
2.0
V
Differential Inputs (TPIN, TXIN)
TPIN+, TPIN
Common Mode Input Voltage
2.2
V
CC
V
TPIN+, TPIN
Differential Input Voltage
1.5
V
TPIN+, TPIN
Differential Input Resistance
10
k
W
TPIN+, TPIN
Common Mode Input Current
+10
A
TXIN+, TXIN
Input Voltage HIGH (V
IH
)
V
CC
1.165
V
CC
0.88
V
TXIN+, TXIN
Input Voltage LOW (V
IL
)
V
CC
1.810
V
CC
1.475
V
TXIN+, TXIN
Input Current LOW (I
IL
)
0.5
A
TXIN+, TXIN
Input Current HIGH (I
IH
)
50
A
Differential Outputs (SD, RXOUT, TPOUT)
SD+, SD, RXOUT+, RXOUT
Output Voltage HIGH (V
OH
)
Note 3
V
CC
1.025
V
CC
0.88
V
SD+, SD, RXOUT+, RXOUT
Output Voltage LOW (V
OL
)
Note 3
V
CC
1.81
V
CC
1.62
V
TPOUT+, TPOUT
Differential Output Current HIGH
V
OUT
= V
CC
0.5, Note 2
19.0
21.0
mA
ABSOLUTE MAXIMUM RATINGS
Absolute maximum ratings are limits beyond which the
life of the integrated circuit may be impaired. All
voltages unless otherwise specified are measured with
respect to ground.
V
CC
Supply Voltage Range .................. GND 0.3V to 6V
Input Voltage Range
Digital Inputs ..................... GND 0.3V to VCC + 0.3V
Output Current
TPOUT+/TPOUT, SD, RXOUT ...................... 50mA
All other outputs ................................................. 10mA
Junction Temperature .............................................. 150C
Storage Temperature ................................ 65C to 150C
Lead Temperature (Soldering, 10 sec) ..................... 260C
Thermal Resistance (
q
JA
)
PLCC ............................................................... 60C/W
TQFP ............................................................... 80C/W
OPERATING CONDITIONS
VCC Supply Voltage .......................................... 5V 5%
T
A
, Ambient Temperature ............................... 0C to 70C
RTSET ............................................................. 2k
W 1%
RRSET ........................................................ 9.53k
W 1%
Receive transformer insertion loss ..................... < 0.5dB
ML6674
4
ELECTRICAL CHARACTERISTICS
(CONTINUED)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Differential Outputs (SD, RXOUT, TPOUT) (Continued)
TPOUT+, TPOUT
DifferentialOutput Current LOW
V
OUT
= V
CC
0.5, Note 2
0
0.1
mA
TPOUT+, TPOUT
Output Current Offset
0.5
mA
TPOUT+, TPOUTV
OUT
= V
CC
Output Amplitude Error
Note 2
5.0
5.0
%
TPOUT+, TPOUTV
OUT
= V
CC
1.1V
Output Voltage Compliance
2.0
+2.0
%
AC Characteristics
TPOUT+, TPOUT
Rise/Fall Time
1.5
2.0
2.5
ns
TPOUT+, TPOUT
Output Jitter
0.5
ns
RXOUT+, RXOUT
Rise/Fall Time
5
ns
RXOUT+, RXOUT
Output Jitter
2.0
ns
Note 1. Limits are guaranteed by 100% testing, sampling, or correlation with worst-case test conditions.
Note 2. Output current amplitude is determined by I
OUT
= 32 x 1.25V/RTSET.
Note 3. Output voltage levels are specified when terminated by 50
W to V
CC
-2V or equivalent load.
ML6674
5
FUNCTIONAL DESCRIPTION
The ML6674 transceiver is a physical media dependent
transceiver that allows the transmission and reception of
155 Mbps data over 100 meters over shielded twisted pair
cable or category 5 unshielded twisted pair cable.
The transmit section accepts NRZ data, sending the
information on a two pin current driven transmitter. The
transmitted output passes through an external low pass
filter and transformer before entering the connectors to the
STP or UTP cable. The output amplitude of the transmitted
signal is programmable through the external RTSET
resistor.
The receive section accepts NRZ coded data after it
passes through an isolation transformer and band limiting
filter. The adaptive equalizer is used to compensate for
the amplitude and phase distortion incurred from the
cable. The adaptive control section determines the signal
amplitude (and therefore the cable length) and adjusts the
equalizer accordingly. As the input signal amplitude
diminishes, the amount of equalization increases until it
reaches its maximum (Figure 1).
The receiver also includes the Baseline Wander correction
circuitry. The circuit will compensate and track the DC
baseline wander caused by DC imbalance of the received
data. A 10pF capacitor can be connected between TPIN+
and TPIN to improve Bit Error Rate.
The adaptive control block governs both the equalization
level as well as the signal detection status. Signal detect
is asserted when the equalizer control loop settles, or
when loop back is asserted. When the input signal is
small, the equalization will be at its maximum.
After the signal has been equalized, it is fed through the
loopback multiplexer onto the RXOUT pins.
Figure 1 shows a typical gain vs frequency plot of the
adaptive equalizer for 0, 25, 50, 75 and 100 meter
category 5 cable lengths.
TRANSMISSION
PECL level scrambled NRZ data is received by the
ML6674 and the current driven transmitter then sent the
data to the filter/transformer module. The transmit
amplitude is controlled by one external resistor, RTSET.
I
V
RTSET
OUT
=
32 125
.
For ATM UTP applications the transmit amplitude is 1V
peak to peak. The termination at the transmitter output is
50. Therefore the transmit current I
OUT
= 1/50 = 20 mA.
Thus,
RTSET
V
mA
k
=
=
32 125
20
2
.
The transmitter may be disabled via the TXOFF pin. When
this pin is pulled low, the transmitter's output goes to a
high impedance state and no current flows through the
transformer.
ADAPTIVE EQUALIZATION
During transmission of data over UTP (unshielded twisted
pair), distortion and ISI are caused by dispersion in the
cable. Equalization is used to overcome this signal
corruption. However, the distortion is frequency
dependent and cable length dependent. Therefore, in most
practical cases, the TP port characteristic is unknown and
it is impractical to tune the equalizer specifically to each
individual port. Hence, adaptive equalizer is used in the
TP-PMD to ensue proper compensation of the received
signal.
By using adaptive equalizer, the receiver automatically
compensates different length of cable without over
equalizing or under equalizing the line. The ML6674
monitors the amplitude of the received signal to
determine the cable length and adjust the equalizer
accordingly. The input signal level is inversely
proportional to the cable length. Therefore, as the signal
level decreases, the amount of equalization is increased
to compensate for the line loss.
ML6672 COMPATIBILITY
The ML6674 implements the Baseline Wander correction
circuit, in addition to providing the functionality of the
existing ML6672 device. The ML6674 is plug-compatible
with the ML6672 with the following notes:
In the ML6674 design, the RTSET resistor must be
2.0k
W
In the ML6674 design, the following passive
components used in the ML6672 design may be
eliminated from the ML6674 design
-- RSET resistor
-- RTH resistor
-- CAP1 capacitor
-- CAP2 capacitor
Figure 1. Equalization Range
20
15
10
5
0
1 x 106
1 x 107
1 x 108
1 x 109
ML6674
6
Note 1. Split 100K ECL terminations are 82
W and 130W to VCC and GND respectively.
Note 2. Recommended power supply bypass capacitors are 0.1F with optional 10F tantalum in parallel.
Note 3. Transformer turns ratio is 1:1.
Note 4. LPBK and TXOFF inputs are active LOW.
Application Example of ML6674 Configured for 1.0V
P-P
Transmit Amplitude on C5 UTP.
ML6674 ATM UTP
TRANSCEIVER
TXIN+
TXIN
SD+
SD
RXOUT+
RXOUT
TPOUT+
TPOUT
TPIN+
CMREF
TPIN
RTSET2
RTSET1
RVCCA
TVCCA
TVCCD
RVCCD
LPBK TXOFF TGNDD TGNDA RGND
RRSET1 RRSET2
+5.0V
50
50
50
50
0.1
F
10pF
0.1
F
0.1
F
0.1
F
0.1
F
0.1
F
9.53K 1%
2.0K 1%
+5.0V
FROM PHY
TO PHY
NOTE 1
TO PHY
FROM PHY
+5.0V
+5.0V
+5.0V
TRANSFORMER
FILTER
MODULE
TRANSFORMER
FILTER
MODULE
TO MIC
FROM MIC
FOR THE TRANSFORMER
CM CHOKE, USE:
XFMRS INC. XF3506SIP
BEL FUSE 0558-5999-00
VALOR PT4172
PULSE PE-68508
ML6674
7
PHYSICAL DIMENSIONS
inches (millimeters)
0.048 MAX
(1.20 MAX)
SEATING PLANE
0.354 BSC
(9.00 BSC)
0.276 BSC
(7.00 BSC)
1
0.276 BSC
(7.00 BSC)
0.354 BSC
(9.00 BSC)
9
25
17
0.032 BSC
(0.8 BSC)
PIN 1 ID
0.012 - 0.018
(0.29 - 0.45)
0.037 - 0.041
(0.95 - 1.05)
0.018 - 0.030
(0.45 - 0.75)
0.003 - 0.008
(0.09 - 0.20)
0 - 8
Package: H32-7
32-Pin (7 x 7 x 1mm) TQFP
0.098 - 0.112
(2.49 - 2.85)
PIN 1 ID
SEATING PLANE
0.585 - 0.595
(14.86 - 15.11)
0.450 - 0.456
(11.43 - 11.58)
0.013 - 0.021
(0.33 - 0.53)
0.165 - 0.180
(4.06 - 4.57)
1
0.550 - 0.556
(13.97 - 14.12)
0.485 - 0.495
(12.32 - 12.57)
9
17
25
0.490 - 0.530
(12.45 - 13.46)
0.025 - 0.045
(0.63 - 1.14)
(RADIUS)
0.050 BSC
(1.27 BSC)
0.019 - 0.021
(0.48 - 0.51)
0.026 - 0.032
(0.66 - 0.81)
0.390 - 0.430
(9.90 - 10.92)
0.042 - 0.048
(1.07 - 1.22)
0.148 - 0.156
(3.76 - 3.96)
Package: Q32
32-Pin PLCC
ML6674
8
DS6674-01
ORDERING INFORMATION
PART NUMBER
TEMPERATURE RANGE
PACKAGE
ML6674CQ
0C to 70C
32-Pin PLCC (Q32)
ML6674CH
0C to 70C
32-Pin TQFP (H32-7)
Micro Linear 1999.
is a registered trademark of Micro Linear Corporation. All other
trademarks are the property of their respective owners.
Products described herein may be covered by one or more of the following U.S. patents: 4,897,611;
4,964,026; 5,027,116; 5,281,862; 5,283,483; 5,418,502; 5,508,570; 5,510,727; 5,523,940; 5,546,017;
5,559,470; 5,565,761; 5,592,128; 5,594,376; 5,652,479; 5,661,427; 5,663,874; 5,672,959; 5,689,167;
5,714,897; 5,717,798; 5,742,151; 5,747,977; 5,754,012; 5,757,174; 5,767,653; 5,777,514; 5,793,168;
5,798,635; 5,804,950; 5,808,455; 5,811,999; 5,818,207; 5,818,669; 5,825,165; 5,825,223; 5,838,723;
5.844,378; 5,844,941. Japan: 2,598,946; 2,619,299; 2,704,176; 2,821,714. Other patents are pending.
Micro Linear makes no representations or warranties with respect to the accuracy, utility, or completeness
of the contents of this publication and reserves the right to makes changes to specifications and product
descriptions at any time without notice. No license, express or implied, by estoppel or otherwise, to any
patents or other intellectual property rights is granted by this document. The circuits contained in this
document are offered as possible applications only. Particular uses or applications may invalidate some of
the specifications and/or product descriptions contained herein. The customer is urged to perform its own
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whatsoever, and disclaims any express or implied warranty, relating to sale and/or use of Micro Linear
products including liability or warranties relating to merchantability, fitness for a particular purpose, or
infringement of any intellectual property right. Micro Linear products are not designed for use in medical,
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2092 Concourse Drive
San Jose, CA 95131
Tel: 408/433-5200
Fax: 408/432-0295
www.microlinear.com
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