SN75LBC086 Datasheet, PDF (1/11 Pages) Texas Instruments – DIFFERENTIAL I/O DRIVER/RECEIVER PAIR WITH SQUELCH, JABBER CONTROL, AND COLLISION DETECTION

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SN75LBC086
DIFFERENTIAL I/O DRIVER/RECEIVER PAIR
WITH SQUELCH, JABBER CONTROL, AND COLLISION DETECTION
SLLS120A − JUNE 1991 − REVISED SEPTEMBER 1991
• Meets or Exceeds the IEEE STD 802.3I,
Type 10BASE-T
• Differential (Twisted-Pair) I/O
Driver/Receiver
• High-Speed Receiver . . . t_pd = 50 ns Max
• Receiver Squelch Circuit Integrity Improved
With Noise Filter
• Jabber Control Prevents Network Lockup
• Collision Detection for Multiple-User
Networks
• Data Link Integrity Monitored With Link
Test Pulse
• Externally Addressable Test Register
Controls Signal Quality Error Testing
• CMOS and Raised ECL Compatible
• 24-Terminal, 300-mil Dual-In-Line Package
DW PACKAGE
(TOP VIEW)
CLKOUT ₁
TXDATAA 2
TXDATAB 3
TXEN 4
GND (L) 5
V_CC(L) 6
GND (L) 7
RXDATAA 8
RXDATAB 9
RXEN 10
LOOP ¹¹
LINK ¹²
24 ^X1
23 X2
22 SQEEN
21 TX+
20 TX−
19 GND (P)
18 V_CC(P)
17 FULLD
16 RX+
15 RX−
14 _CTL
13 _JABB
description
The SN75LBC086 is a single-channel differential driver/receiver interface device for the medium attachment
unit (MAU) used in 10-MHz twisted-pair Ethernet applications. The device uses a 5-V supply and is designed
to interface with two pairs of telephone-grade twisted-pair cables coupled through isolation transformers. The
functional components of the device include a differential receiver and driver, receiver squelch with noise filter,
jabber controls, collision detection, data link monitor, and signal quality error (SQE) testing. The LinBiCMOS
process technology is used in the device design to ensure analog precision, low power, and high-speed
operation.
The device contains an elaborate receiver-squelch circuit^† that provides an improved level of noise rejection
by qualifying the incoming signal stream with three different criteria. First, the signal is compared to a set
threshold voltage level. Then, the pulse duration is compared to a set time window. Last, the signal must follow
a set pattern of positive and negative pulses before the circuit finally opens the receiver channel to the incoming
data packet.
The jabber control is designed to prevent a defective controller from locking up the network by limiting the data
packet transmission time to 20 to 30 ms. When a packet length exceeds 20 to 30 ms, the driver is turned off for
about 600 ms. The driver-enable input must be made inactive by the controller during this period before the
jabber control will release the driver. The JABB output is active (high) when a jabber condition exists.
Collision detection is used to arbitrate access to the multiuser network. This detection is done logically by
monitoring the receive line for a valid signal during a driver transmission. When a collision is detected, this device
informs the controller with an active-high CTL output. After a valid packet transmission, the device also performs
a signal quality error test causing the CTL output to go active (high). This test is disabled when the SQEEN input
goes inactive (high).
The device tests data-link integrity during the idle state by periodically driving the driver line with a unipolar pulse
called a link-test pulse. The receiver looks for this link-test pulse on the receive line. A failed line link is indicated
by a high-impedance state at the LINK output. This output drives an LED for monitoring if needed.
An internal test register is externally controlled with inputs FULLD and LOOP to select the device testing mode.
When in the test mode, serial test-mode control patterns are clocked into the test register through input SQEEN.
These control patterns select various modes to test the internal circuits.
† _{Embodies technology covered by one or more Digital Equipment Corporation Patents.}
LinBiCMOS is a trademark of Texas Instruments Incorporated.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
Copyright  1991, Texas Instruments Incorporated
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