April 1997

ML4642 AUI Multiplexer

GENERAL DESCRIPTION

The ML4642 AUI Multiplexer contains all the necessary
drivers/receivers and control logic to implement a 2 port
MAU when used in conjuction with a transceiver chip
which has a standard 802.3 AUI interface. In addition, the
ML4642 is capable of operating in stand-alone mode
where it interconnects two DTEs in the absence of a
network MAU. Several ML4642s can be cascaded
together to implement a 4 or 8 port MAU or stand-alone
device.

Logic within the ML4642 detects collisions resulting from
multiple DTEs transmitting simultaneously. In addition,
collision signals received from a transceiver attached at
the MAU port are propagated to both of the DTE ports.
Jabbering DTEs are prevented from loading down the
network by internal jabber timers which disable babbling
ports.

FEATURES

IEEE 802.3 compliant AUI interfaces assure
compatibility with any AUI ready devices

No crystal or clock input

On-chip Jabber logic, Collision Detection, and SQE
test with enable/disable option

Selectable Loopback, Jabber, and SQE Test allows
cascading of multiple chips to increase DTE port

BLOCK DIAGRAM

GND

DTE
AUI

INTERFACE

MAU

AUI

INTERFACE

CONTROL

LOGIC

JABBER

DI MUX

CI MUX

SQE SOURCE

LED DRIVERS

+5V

61.9K

RRSET

TXOUTP

TXOUTN

RXINP

RXINN

CDINP

CDINN

JAB1/JDIS

JAB2

CDLED

RXLED/LPBK/SQE

TXLED1

TXLED2

MAU

AUI

INTERFACE

TXIN1P

TXIN1N

RXOUT1P

RXOUT1N

CDOUT1P

CDOUT1N

TXIN2P

TXIN2N

RXOUT2P

RXOUT2N

CDOUT2P

CDOUT2N

DO MUX

ML4642

PIN DESCRIPTIONS

PIN NO.

NAME

FUNCTION

DESCRIPTION

RXLED/LPBK/SQE

I/O

Active low receive LED driver for MAU port. If tied to ground, this pin
enables internal loopback of the active TXIN pair to the RXOUT pairs
and enables SQE test. If tied to 0.6 volts internal loopback is enable but
SQE test is disabled. SQE and loopback are disabled when this pin is
pulled high.

RXINP

Input

Receive signal pair for MAU port.

RXINN

Onput

Receive signal pair for MAU port.

JAB1/JDIS

I/O

Active low jabber LED driver for DTE port 1. If tied to ground, the
jabber function is disabled at TXIN1 and TXIN2.

RRSET

Input

Bias setting external resistor, 61.9K�.

Power

+5 volt power supply

TXOUTP

Output

Transmit signal pair for MAU port.

TXOUTN

Output

Transmit signal pair for MAU port.

TXLED1

Output

Open collector, active low transmit LED driver for DTE AUI port 1.

TXLED2

Output

Open collector, active low transmit LED driver for DTE AUI port 2.

TXIN2P

Input

Transmit signal pair for DTE port 2.

TXIN2N

Input

Transmit signal pair for DTE port 2.

TXIN1P

Input

Transmit signal pair for DTE port 1.

TXIN1N

Input

Transmit signal pair for DTE port 1.

Power

+5 volt power supply

CDOUT2N

Output

Collision signal pair for DTE port 2.

CDOUT2P

Output

Collision signal pair for DTE port 2.

CDLED

Output

Open collector, active low collision LED driver.

CDINN

Input

Collision signal pair for MAU port.

CDINP

Input

Collision signal pair for MAU port.

JAB2

Output

Open collector, active low jabber LED driver for DTE port 2.

CDOUT1P

Output

Collision signal pair for DTE port 1.

CDOUT1N

Output

Collision signal pair for DTE port 1.

GND

Ground

GND.

RXOUT2P

Output

Receive signal pair for DTE port 2.

RXOUT2N

Output

Receive signal pair for DTE port 2.

RXOUT1N

Output

Receive signal pair for DTE port 1.

RXOUT1P

Output

Receive signal pair for DTE port 1.

ML4642

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.

Power Supply Voltage Range V

. . . GND �0.3V to 6.0V

Input Current RRSET, JAB1/JABD, JAB2, CDLED,

RxLED/LPBK/SQE, TxLED1, TxLED2 . . . . . . . . . . 60mA

Junction Temperature . . . . . . . . . . . . . . . . . . . . . . 150�C
Storage Temperature . . . . . . . . . . . . . . . . �65�C to 150�C
Lead Temperature (Soldering 10 seconds) . . . . . . . 260�C
Thermal Resistance (

)

SSOP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109�C/W
PLCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68�C/W

OPERATING CONDITIONS

Supply Voltage (V

) . . . . . . . . . . . . . . . . . . . 5V � 10%

LED on Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10mA
RRSET . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61.9k� � 1%

ELECTRICAL CHARACTERISTICS

Unless otherwise specified T

= 0�C to 70�C, V

= 5V � 10%. (Notes 1, 2)

PARAMETER

CONDITIONS

MIN

TYP.

MAX

UNITS

Power Supply Current I

= 5V, (Note 3)

120

LED Drivers: V

=510� for CDLED, TXLED1,2, JAB2

0.8

=270� for JAB1/JDIS,

RxLED/LPBK/SQE

1.2

2.5

3.5

Transmit Squelch Voltage Level

�300

�250

�200

(Tx+, Tx�)

Differential Output Voltage

�550

�1200

Common Mode Output Voltage

4.0

Differential Output Voltage Imbalance

�40

RxLED/LPBK/SQE

SQE Enabled/Loopback Enabled

0.3

SQE Disabled/Loopback Enabled

0.4

0.6

0.8

Note 1: Limits are guaranteed by 100% testing, sampling or correlation with worst case test conditions.
Note 2: Low Duty cycle pulse testing is performed at T

Note 3: This does not include the current from the AUI pull down resistors or the LED output pins.

ML4642

AC ELECTRICAL CHARACTERISTICS

SYMBOLS

PARAMETER

MIN

TYP.

MAX

UNITS

TRANSMIT

TXNPW

Transmit Turn-On Pulse Width

TXFPW

Transmit Turn-Off Pulse Width

180

XODY

Transmitter Turn-On Delay

TXLP

Transmit Loopback Startup Delay

TXSDY

Transmit Steady State Prop. Delay

TXJ

Transmitter Jitter

RECEIVE

RXODY

Receive Turn-On Delay

RXSDY

Receive Steady State Prop. Delay

RXJ

Receiver Jitter

Differential Output Rise Time

20% to 80% (Rx+/�, COL+/�)

Differential Output Fall Time

20% to 80% (Rx+/�, COL+/�)

COLLISION

CPSQE

Collision Present to SQE Assert

200

SQEXR

Time for SQE to Deactivate after a collision

100

900

CLF

Collision Frequency

8.5

11.5

MHz

CLPDC

Collision Pulse Duty Cycle

SQEDY

SQE Test Delay (Tx Inactive to SQE)

0.6

1.1

1.6

�s

SQETD

SQE Test Duration

0.5

1.0

1.5

�s

SQEB

SQE Blank Period

�sec

JABBER, LINK TEST AND LED TIMING

JAD

Jabber Activation Delay

13.5

JRT

Jabber Reset Unjab Time

250

450

750

JSQE

Delay from Outputs Disabled to

100

Collision Oscillator On

LEDT

CDLED, RxLED, TxLED1, TxLED2 On Time

300

ML4642

360

TXIN1P

TXIN1N

RXOUT1P

RXOUT1N

CDOUT1P

CDOUT1N

TXIN2P

TXIN2N

RXOUT2P

RXOUT2N

CDOUT2P

CDOUT2N

TXOUTP

TXOUTN

RXINP

RXINN

CDINP

CDINN

JAB1/JABD

JAB2

CDLED

TXLED1

TXLED2

RXLED/LPBK/SQE

GND

Switch Option
1. Receive LED with Internal/External MAU
2. No MAU/No SQE
3. No MAU with SQE

ML4642

0.1

0.01

+5V

61.9K

+5V

RRSET

510

270

+5V

TO MAU

TO DTE 1

TO DTE 2

7.15k

Before data will be transmitted to the TXOUT and RXOUT
pins from the TXIN pins it must meet the unsquelch
requirements of the TXIN receiver circuitry. The squelch
circuitry prevents any noise on the TXIN wires from being
misinterpreted as data and transmitted to the TXOUT and
RXOUT pins. The squelch circuit rejects signals with pulse
widths less than typically 20ns and voltage levels more
positive than �250mV. Once the TXIN receiver is
unsquelched it remains so until reception of the input idle
signal, which is detected when the TXIN signal is more
positive than �170mV for longer than 180ns.

RECEPTION

The receive function consists of detecting data at the
RXIN differential receiver of the MAU port transmitting
this data to both DTE port RXOUT pairs.

Figure 9 is a block diagram of a Two Port Multiplexer
using the ML4642 chip. All AUI interfaces are shown AC
coupled as they would be in an AUI multiplexer which
does not include the MAU circuitry on the same board.

TRANSMISSION

The transmit function consists of detecting data on either
of the TXIN differential receivers (TXIN1 or TXIN2) and
transmitting this data out the TXOUT differential driver at
the MAU port as well as both RXOUT1 and RXOUT2
drivers of the DTE ports. (Note: the looping back of data
received at a TXIN pair to the RXOUT pairs is discussed in
the Loopback section.)

Figure 9. Two Port AUI Multiplexer

FUNCTIONAL DESCRIPTION

ML4642

Before data will be transmitted to the RXOUT pins of the
DTE ports it must meet the unsquelch requirements for the
RXIN receiver circuitry. The squelch circuitry at the RXIN
differential receiver input performs the same function as
that of the TXIN squelch circuitry using the same noise
rejection criteria.

COLLISION

There are two conditions that constitute a collision from
the point of view of the ML4642:

a) If data is received at the TXIN inputs of both DTE ports

simultaneously a local collision occurs within the
ML4642.

b) If the CDIN input is active at any time other than the

inter-packet gap window allowed for the SQE Test
function described below.

In either of the above circumstances it is necessary for the
ML4642 to drive the CDOUT pairs on both DTE ports with
the collision signal. The collision signal consists of a 10
MHz +/� 15% square wave matching the AUI
specifications and capable of driving a 78� load. The
collision signal shall turn on within 2 bit times of the
origination of the collision condition and shall turn off
within 2�5 bit times after the collision condition subsides.

During a collision condition there are two sources for data
to be transmitted to TXOUT, TXIN1 and TXIN2. The highest
priority source for data to be transmitted to TXOUT is the
TXIN1 receiver.

For example if TXIN2 begins transmission then TXIN1 turns
on, the collision oscillator will turn on and TXOUT will
switch from TXIN2 to TXIN1. If the collision ends by
TXIN1 turning off first, TXOUT will switch from TXIN1 to
TXIN2, and 2�5 bit times later the collision oscillator will
turn off.

The MAU port's CDIN receiver contains squelch circuitry
to prevent noise from causing the erroneous detection of a
collision signal. A signal on the CDIN pair will not be
considered active until it exceeds the same squelch
requirements as those of the TXIN receivers.

LOOPBACK

The loopback function allows the ML4642 to emulate a
coaxial transceiver by propagating the TXIN data back
out the RXOUT pair of the same DTE port that is sourcing
the data as well as the RXOUT pair of the idle DTE port.
This allows the Ethernet controller sending the data to
monitor its transmit packets and detect network faults.

The loopback function is enabled at both DTE ports when
the RXLED pin is tied to ground, or 0.6 volts.

SQE TEST FUNCTION

The Signal Quality Error (SQE) Test function allows the
DTE to determine whether or not the collision detection
circuitry is functional. After each transmission, during the

inter-packet gap time, the collision signal will be
activated on the CDOUT pair of the same port as the
TXIN pair which received the packet, for typically 1 �s.
The SQE function will not be activated on DTE ports of
the ML4642 which are in the Jabber state. The SQE
function is enabled on both DTE ports when the RXLED/
LPBK/SQE pin is grounded.

JABBER

The jabber function prevents a babbling transmitter from
loading down the network. Within the ML4642 is a jabber
timer on each TXIN receiver. Each timer starts at the
beginning of a received packet and resets at the end of
each packet. If a packet lasts longer than 7 to 20ms the
jabber logic disables its corresponding TXIN receiver (thus
preventing its data from being retransmitted) and
generates a collision signal on the babbling port's CDOUT
pair. When the TXIN pair finally goes idle, a second timer
measures 0.5 seconds of idle on TXIN prior to re-enabling
the receiver and turning off the collision signal. If the
TXIN pair becomes active again before the 0.5 seconds
has expired, the timer is reset and measures another 0.5
seconds of idle time.

The jabber function can be disabled on both ports by tying
the JAB1/JABD pin to ground.

LED DRIVERS

The ML4642 has six LED driver pins. Each DTE port has a
transmit LED and a jabber LED and the MAU port has a
receive LED. Additionally, there is a collision LED which
indicates the presence of a collision condition. All LED
drivers are active low 10mA current sources.

The TXLED, RXLED, and CDLED outputs have 50ms pulse
stretchers on them to enable the LEDs to be visible. The
JLED outputs do not have pulse stretchers on them
because their conditions occur long enough for the LEDs
to be visible.

Two of the ML4642 LED outputs serve as configuration
pins as well. RXLED/LPBK/SQE and JAB1/JDIS may be
tied through a resistor to V

, tied through a resistor and a

LED to V

or grounded. Additionally RXLED/LPBK/SQE

may be tied to a specific voltage. When these pins are
grounded or tied to a 0.6 Volts they become configuration
inputs. Otherwise when tied high they become status
outputs.

CASCADING THE ML4642 FOR 4 AND 8 PORT DESIGNS

The configurability of such functions as loopback, jabber,
and SQE allows ease of cascading multiple ML4642 chips
for larger fan-out designs. Figure 10 shows a four port AUI
Multiplexer design. For a type 0 configuration both jabber
and transmit LEDs are available on a per port basis for
status. The RXLED/LPBK/SQE pins are tied through a
resistor to 5 volts, and CDLED is wire OR'ED with the
other chip for one collision detect status LED per system.
There is also only one receive LED status output which is
displayed in a type 2 configuration. This particular pin in

FUNCTIONAL DESCRIPTION

ML4642

Figure 10. Four Port AUI Multiplexer

360

TXIN1P

TXIN1N

RXOUT1P

RXOUT1N

CDOUT1P

CDOUT1N

TXIN2P

TXIN2N

RXOUT2P

RXOUT2N

CDOUT2P

CDOUT2N

TXOUTP

TXOUTN

RXINP

RXINN

CDINP

CDINN

JAB1/JABD

JAB2

CDLED

TXLED1

TXLED2

RXLED/LPBK/SQE

GND

ML4642

RSSET

TO DTE 1

TO DTE 2

360

TXIN1P

TXIN1N

RXOUT1P

RXOUT1N

CDOUT1P

CDOUT1N

TXIN2P

TXIN2N

RXOUT2P

RXOUT2N

CDOUT2P

CDOUT2N

TXOUTP

TXOUTN

RXINP

RXINN

CDINP

CDINN

JAB1/JABD

JAB2

CDLED

TXLED1

TXLED2

RXLED/LPBK/SQE

GND

Switch Options
1. Receive LED with Internal/External MAU
2. No MAU/No SQE
3. No MAU with SQE

ML4642

RSSET

TO DTE 3

TO DTE 4

0.1

0.01

+5V

360

TXIN1P

TXIN1N

RXOUT1P

RXOUT1N

CDOUT1P

CDOUT1N

TXIN2P

TXIN2N

RXOUT2P

RXOUT2N

CDOUT2P

CDOUT2N

TXOUTP

TXOUTN

RXINP

RXINN

CDINP

CDINN

JAB1/JABD

JAB2

CDLED

TXLED1

TXLED2

RXLED/LPBK/SQE

GND

ML4642

0.1

0.01

+5V

RSSET

TO MAU

0.1

0.01

+5V

510

270

+5V

270

510

+5V

510

270

+5V

270

61.9k

61.9K

61.9k

Type 0

Type 2

270

+5V

7.15k

FUNCTIONAL DESCRIPTION

ML4642

SQE TEST WHEN CASCADING

As mentioned before, after each transmission during the
interpacket gap time the collision signal will be activated
on the CDOUT pair of the same port as the TXIN pair
which received the packet. When cascading ML4642s to
implement 4 or 8 port designs, the path is remembered
and followed to acheive this function. The paths that did
not carry the transmit data blocks CDOUT for 4-7 �sec
after transmission to guarantee that only the port that
transmitted will see SQE test.

a type 2 configuration offers three options. In option 1,
when tied to +5 volts through a resistor and an LED, an
internal or external MAU will be connected. For stand-
alone operation without an internal or external MAU a
loopback is required. Option 2 allows loopback with no
SQE test while option 3 provides loopback with an SQE
test.

An eight port design is accomplished in the same way as
shown in the block diagram in Figure 11. In an eight port
design Type 0 and Type 2 configuration remain the same
as in a four port design. Type 1 however only differs from
Type 2 by tying RXLED/LPBK/SQE through a resistor to +5
volts. Table 1 summerizes all of the different LED
configurations.

TABLE 1. LED Configurations for 2, 4, and 8 Port Designs

JAB1/JABD

RXLED/LPBK/SQE

JAB2

CDLED

TXLED1

TXLED2

Two Port AUI Mux

LED

GND, 0.6V, LED

LED

Type 0

LED

270� to +5V

LED

WIRE'ORED

LED

Type 1

GND

270� to +5V

Type 2

GND

GND, 0.6V, LED

DTE PORT 1

DTE PORT 2

DTE PORT 3

DTE PORT 4

DTE PORT 5

DTE PORT 6

DTE PORT 7

DTE PORT 8

ML4642

MAU PORT

TYPE 0

TYPE 1

TYPE 2

Figure 11. Eight Port AUI Multiplexer

FUNCTIONAL DESCRIPTION

ML4642

PHYSICAL DIMENSIONS inches (millimeters)

SEATING PLANE

0.205 - 0.213

(5.20 - 5.40)

0.301 - 0.313

(7.65 - 7.95)

0.397 - 0.407

(10.08 - 10.34)

0.009 - 0.015

(0.23 - 0.38)

0.026 BSC
(0.65 BSC)

0.022 - 0.030

(0.55 - 0.95)

0.068 - 0.078

(1.73 - 1.98)

0.002 - 0.008

(0.05 - 0.20)

0.066 - 0.070

(1.68 - 1.78)

0.004 - 0.008

(0.10 - 0.20)

0� - 8�

PIN 1 ID

Package: R28

28-Pin SSOP

0.099 - 0.110

(2.51 - 2.79)

PIN 1 ID

SEATING PLANE

0.485 - 0.495

(12.32 - 12.57)

0.450 - 0.456

(11.43 - 11.58)

0.013 - 0.021

(0.33 - 0.53)

0.165 - 0.180

(4.06 - 4.57)

0.450 - 0.456

(11.43 - 11.58)

0.485 - 0.495

(12.32 - 12.57)

0.025 - 0.045

(0.63 - 1.14)

(RADIUS)

0.050 BSC
(1.27 BSC)

0.009 - 0.011

(0.23 - 0.28)

0.026 - 0.032

(0.66 - 0.81)

0.042 - 0.048

(1.07 - 1.22)

0.148 - 0.156

(3.76 - 3.96)

0.042 - 0.056

(1.07 - 1.42)

0.390 - 0.430
(9.90 - 10.92)

0.300 BSC
(7.62 BSC)

Package: Q28

28-Pin PLCC

ML4642

Micro Linear reserves the right to make changes to any product herein to improve reliability, function or
design. Micro Linear does not assume any liability arising out of the application or use of any product
described herein, neither does it convey any license under its patent right nor the rights of others. The
circuits contained in this data sheet are offered as possible applications only. Micro Linear makes no
warranties or representations as to whether the illustrated circuits infringe any intellectual property rights of
others, and will accept no responsibility or liability for use of any application herein. The customer is urged
to consult with appropriate legal counsel before deciding on a particular application.

2092 Concourse Drive

San Jose, CA 95131

Tel: 408/433-5200

Fax: 408/432-0295

ORDERING INFORMATION

PART NUMBER

TEMPERATURE RANGE

PACKAGE

ML4642CR

0�C to 70�C

28-Pin SSOP (R28)

ML4642CQ

0�C to 70�C

28-Pin PLCC (Q28)

� Micro Linear 1997

is a registered trademark of Micro Linear Corporation

Products described in this document may be covered by one or more of the following patents, U.S.: 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; Japan: 2598946; 2619299. Other patents are pending.

DS4642-01

Электронный компонент: ML4642CR