ETC 80C25

Full Duplex
80C25
80C25
AutoDUPLEXTM
CMOS Ethernet Interface Adapter
in 28L Package
96345
Functional Features
Note: Check for latest Data Sheet revision
before starting any designs.
■ Low Power CMOS Technology Ethernet Serial
Interface Adapter with Integrated Manchester
Code Converter (MCCTM), AUI and 10Base-T
Transceiver with Output Wave Shaping and on
chip filters.
SEEQ Data Sheets are now on the Web, at
www.lsilogic.com.
This document is an LSI Logic document. Any
reference to SEEQ Technology should be
considered LSI Logic.
■ Meets IEEE 802.3 10Base-5, 10Base-2, 10Base-T
Standards
■ Direct Interface to SEEQ & INTEL Controllers,
See the 80C26 Data Sheet for Direct Interface to
AMD and NSC Controllers
Interface Features
■ Meets IEEE 10Base-T Standards and IEEE 802.3
standards for AUI.
■ Automatic or Manual Selection of AUI/10Base-T
Interface
■ On Chip Transmit Wave Shaping and Low Pass
Filter Circuits - No External Filters Required
■ Provides AutoDUPLEXTM Detect Function for
SEEQ LAN Controllers, Doubling Bandwidth
to 20 MBits/sec for Switched Networks
■ Link Integrity Test Disable, Selectable Coded
Link Pulse for AutoDUPLEX Mode
■ Direct AUI interface to the Manchester Code
Converter.
General Description
DO –
5
25
TPO +
CI +
6
24
TPO –
CI –
7
23
TPI +
28 Pin PLCC
Top View
TXD
FDPLX_DET 11
19
RXD
The SEEQ 80C25 is a CMOS single chip Ethernet serial
interface adapter with a integrated Manchester Code
Converter (MCC), AUI & 10Base-T transceiver with wave
shaping & filters eliminating the need for external filters.
The 80C25 is designed to interface directly with SEEQ and
Intel Ethernet data link controllers. The chip provides
automatic polarity correction, automatic port selection,
separate analog & digital ground pins & a link disable
feature. It also provides a selectable coded link pulse to
implement AutoDUPLEX function together with SEEQ
family of controllers allowing seamless full duplex operation in switched network implementations doubling network bandwidth to 20 Mbps in 10Base-T. The 80C25 is
typically suitable for adapter boards, motherboards and
stand-alone TP transceiver designs & switching hubs.
RXC
18
20
X1 17
LNK_LED/LNK_DIS 10
GND 2 16
TXEN
VCC2 15
TPI –
21
COL 14
22
9
TXC 13
8
DI –
12
DI +
CSN
■ Low differential and common mode noise on TP
transmit outputs.
26 REXT
FDPLX
28 GND 1
27
1
3
2
4
VCC1
■ Differential Transmit Drivers to support 50 Meters
of AUI Cable Lengths.
CIS
Pin Configuration
TP/AUI
■ Automatic Polarity Correction
DO +
■ Separate Analog/Digital Power and Ground Pins
to Minimize Noise
MCC and AutoDUPLEX are trademarks of SEEQ Technology, Inc.
1
MD400142/D
80C25
80C25 Pin Description
Pin
Name
I/O
1
VCC1
—
2
TP/AUI
I
Pullup To
VCC/2
Description
Power Supply. +5 Volts.
TP or AUI or Autoport Select Input. This pin selects the
interface to the ENDEC. This pin is a three state input that is
internally biased at VCC/2.
TP/AUI
1
float
0
3
CIS
I
Pulldown
TP Port
Autoport
AUI Port
Controller Interface Select Input.
CIS
0
1
SEEQ
Intel
The 80C26 Provides interface to NSC and AMD Controllers.
4
DO +
O
AUI Transmit Output, Positive.
5
DO –
O
AUI Transmit Output, Negative.
6
CI +
I
AUI Collision Input, Positive.
7
CI –
I
AUI Collision Input, Negative.
8
DI +
I
AUI Receive Input, Positive.
9
DI –
I
AUI Receive Input, Negative.
10
LNK_LED
I/O
/LNK_DIS
Link Detect Output and Link Disable Input. This pin consists of an
open drain output transistor. If the pin is tied to DGND, the link test
function is disabled. Otherwise, the pin is a Link Pulse Detect output
and can drive an LED.
LNK_LED = 1
Output Link Pulse Not Detected
LNK_LED = 0
Output
Link Pulse Detected
LNK_LED = DGND
Input
Link Test Function Disabled
11
FDPLX_DET
O
Full Duplex Detect Output. When FDPLX_DET = 0, the device
has been placed in the full duplex mode by either selection or by
the AutoDUPLEX feature.
12
CSN
O
Carrier Sense Output. This controller interface output indicates
valid data and collisions on the receive TP or AUI inputs.
13
TXC
O
Transmit Clock Output. This controller interface output provides
a 10 MHz clock to the controller. Transmit data from the controller on
TXD is clocked in on edges of TXC.
2
MD400142/D
80C25
Pin Description cont’d
Pin
Name
I/O
Description
14
COL
O
Collision Output. This controller interface output is asserted
when collision transmit and receive data occurs and during SQE test.
15
VCC2
—
Power Supply. +5 Volts.
16
GND2
—
Ground. 0 Volts.
17
X1
I
Crystal Oscillator Input. The master clock for the device is
generated by either placing a crystal between X1 and DGND, or
by applying an external clock to X1.
If a crystal is used as the clock source, connect a 1M Ω resistor
between X1 and GND. For external oscillator operation, connect a
470 Ω resistor in series between X1 and clock source.
18
RXC
O
Receive Clock Output. This controller interface output provides
a 10 MHz clock to the controller. Receive data on RXD is clocked
out on edges of RXC.
19
RXD
O
Receive Data Output. This controller interface output contains
receive data decoded from the receive TP/AUI inputs and is
clock out on edges of RXC.
20
TXD
I
Transmit Data Input. This controller interface input contains data
to be transmitted on either TP or AUI transmit outputs and is clocked
in on edges of TXC.
21
TXEN
I
Transmit Enable Input. This controller interface input has to be
asserted when data on TXD is valid.
22
TPI–
I
Twisted Pair Receive Input, Negative.
23
TPI+
I
Twisted Pair Receive Input, Positive.
24
TPO–
O
Twisted Pair Transmit Output, Negative.
25
TPO+
O
Twisted Pair Transmit Output, Positive.
26
REXT
—
Transmit Current Set. An external resistor tied between this pin
and AGND sets the twisted pair transmit output current level on TPO±.
27
FDPLX
I
Pullup to
VCC/2
Full Duplex/AutoDUPLEX Mode Select Input. This pin is a three
state input that is internally biased to VCC/2.
FDPLX
1
float
0
28
GND1
—
Full Duplex Mode
AutoDUPLEX Mode
Normal
Ground. 0 Volts.
3
MD400142/D
80C25
BLOCK DESCRIPTION
Functional Description
The Encoder/Decoder
Manchester encoding is a process of combining the clock
& the data stream together so that they can be transmitted
on the twisted pair interface or AUI at the transceiver side.
Once encoded, the first half contains the complement of
the data and the second half contains the true data, so that
a transition is always guaranteed at the middle of a bit cell.
Data encoding and transmission begins with TXEN going
active, and the subsequent data is clocked on the edges
of TXC and then gets encoded. The end of a transmit
packet occurs at a bit cell center if the last bit is a "ONE" or
at a bit boundary if the last bit is a "ZERO".
The 80C25 is an Ethernet adapter with a integrated Manchester Code Converter, 10Base-T transceiver with on
chip filters. The device contains both 10Base-T and AUI
interfaces compliant with IEEE 802.3 specifications. The
chip is divided into four major blocks, namely (i) The
controller interface (ii) The Encoder / Decoder (iii) The
twisted pair interface and (iv) The AUI. The input signals
are received on the TP or AUI receivers depending on
which is selected. Both the twisted pair and AUI receivers
contain a threshold comparator to validate the signal and
a zero crossing comparator for checking the transitions.
Then the data is sent to the PLL in the decoder to separate
the data from the clock. On the other side, digital transmit
data is clocked into the device via the controller interface.
The data is then sent to the Manchester encoder to be
encoded. Encoded data is then transmitted on the twisted
pair or AUI based on the selected port.
The decoding is a process of recovering the encoded data
stream coming from the receiver side and decoding it back
into the clock and data outputs using the phase locked loop
technique. The PLL is designed to lock into the preamble
of the incoming signal at less than 15 bit times with a
maximum jitter of ±13.5 ns at the TPI or AUI inputs and can
also sample the incoming data with this amount of jitter.
The ENDEC asserts the CSN signal to indicate to the
controller that the data and clock received are valid and
available. There is an inhibit period after the end of a frame
after a node has finished transmitting for 4.4 µs during
which CSN is deasserted irregardless of the state of the
receiver and collision status.
The Controller Interface
The 80C25 is designed to interface directly to all of SEEQ's
Ethernet controllers, and INTEL's 82586/596/592/593
LAN controllers, with the use of CIS Pin. The controller
interface consists of the Transmit/Receive data (TXD/
RXD), transmit/receive Clocks (TXC/RXC), the Transmit
Enable (TXEN) input, the collision output (COLL), the Full
Duplex acknowledgment (FDPLX_DET) and the Carrier
Sense Output (CSN) pins. On the transmit side, data on
TXD is clocked into the device on the edges of TXC clock
output only when the data valid signal (TXEN) is asserted.
On the receive side, data on RXD is clocked out on edges
of RXC. In the SEEQ mode, RXC follows TXC for 1.5 µs
and then switches to the recovered clock. In the Intel
mode, RXC is held low for 1.5 µs while the PLL is acquiring
lock and then switches to the recovered lock. The
FDPLX_DET pin signifies to the controller that full duplex
channels have been established.
Twisted Pair Interface
(a) The transmitter function
The transmitter transfers Manchester encoded data from
the ENDEC to the twisted pair cable. The circuit consists
of a set of functional blocks to provide pre-coded waveshaped, pre-equalized and smoothed waveforms so that
the outputs are made to appear as though it had passed
through a 5-7th order external elliptic passive filter, thereby
eliminating the need for an external filter. The waveform
generator consists of a ROM, DAC, PLL, filter and a output
driver to preshape the output waveform transmitted onto
the twisted pair cable to meet the pulse template requirements outlined in IEEE STD 802.3 and illustrated in figure
12. The DAC first converts the data pulse into a stair
stepped representation of the desired output waveform,
which goes through a second order low-pass filter. The
DAC values are determined from the ROM addresses,
which are chosen to have different values for long and
short data bits so as to shape the pulse to meet the
10Base-T waveform template. The line driver takes the
smoothed current waveform and converts it into an high
current output that can drive the TP directly without any
external filters. The current output is guaranteed to have a
The 80C25 supports SEEQ and INTEL Controllers
according to Table 1.
Table 1. CIS Pin Description
CIS
Controller Interface
0
SEEQ
1
INTEL
4
MD400142/D
GND 2
V
CC2
GND 1
V
CC1
LNK_LED/LNK_DIS
FDPLX_DET
FDPLX
CIS
TP/AUI
COLL
CSN
RXD
RXC
TXEN
TXD
TXC
MODE
INPUTS
AND
OUTPUTS
CONTROLLER
INTERFACE
RECEIVE DATA
TRANSMIT DATA
POLARITY
DETECT
LINK
PULSE
DETECT
TP
SQUELCH
LINK
PULSE
DETECT
PORT
DETECT
AUTO
DUPLEX
DETECT
DAC
AUI
SQUELCH
SOI
DETECT
SOI
GEN
CLOCK
GEN
(PLL)
ROM
TP INTERFACE
COLLISION DATA
Figure 1. 80C25 Block Diagram
COLLISION
DETECT
MANCHESTER
DECODER
(PLL)
MANCHESTER
ENCODER
ENDEC
JABBER
DETECT
–
+
+/–Vth
LP
FILTER
–Vth
–Vth
–
5
+
–
+
+
OSCILLATOR
–
+
+
–
MD400142/D
+
–
+
+
X1
LP
FILTER
–
+
CI–
CI+
RX–
RX+
TX–
TX+
TPI–
TPI+
TPO–
TPO+
REXT
80C25
80C25
The 80C25 is switched on to the AutoDUPLEX mode when
FDPLX is left floating. In this configuration, Full duplex
mode is automatically established by the successful detection of double pulses embedded within the regular link
pulses. The 80C25 sends the double pulses in 16 pulse
intervals constantly on the TPO ± pins and continually
monitors the TPI ± pins for similar type of double pulses
within a time window of 210 ± 6ms. Once the double pulses
are detected, the FDPLX_DET will go low to acknowledge
to the controller that the network will allow simultaneous
transmission and reception on the TP port. The maximum
distance between two consecutive pulses in a double
pulse is 5.4 µs.
very low common mode and differential noise. The interface to the twisted pair cable requires a transformer with a
ratio of 2:1 on transmit and a 1:1 on receive, with two 200
ohm resistors connected as shown in figure 2. The output
driver is a current source. The output current level is set by
the values of the resistor tied between the REXT and
AGND. The current level is determined by the following
equation.
I
= (REXT/10K)* 50 mA
OUT
Though a 10K resistor will meet the template requirements
specified with a no load condition, a capacitive or inductive
loading can influence the level, because the transmitter
has a current source output. So, in a actual application, it
might be necessary to adjust the value to compensate the
loading involved. For example, the bias resistance value
for a loading of 10 pf will be approximately 8K.
The Forced Full-Duplex mode can be established by
setting FDPLX to high.
In this combination, forced full duplex is effectively established and Collision, SQE & the LoopBack functions are
disabled.
(b) The receiver function
The receiver receives the Manchester-encoded data
from the twisted pair lines( TPI ±) and passes it on to the
ENDEC side, where it gets decoded back into the receive
clock RXC and the receive data RXD. The inputs first go
through a receive filter, which is a continuous time 3rd
order low pass filter with a typical 3 dB cutoff frequency of
20-25 Mhz. The filter's output then passes through two
different types of comparators, namely threshold and zero
crossing. The threshold comparator compares the TPI ±
inputs with fixed positive and negative thresholds called
the squelch levels. The zero crossing comparator senses
the transition point on the TPI ± inputs without introducing
excess jitter and the outputs go to the PLL in the decoder.
The receiver is transformer coupled and needs to be
terminated with a 100 Ω resistor or two 50 Ω resistors and
a capacitor as described in figure 2.
(d) Squelch functions
The squelch function is used to discriminate noise from link
test pulses and valid data to prevent the noise from
activating the receiver. It is accomplished by a squelch
comparator which compares the TPI± signals with a fixed
positive and negative squelch value. The output from the
comparator goes to a receive squelch circuit which determines whether the input data is valid or not. If the data is
invalid, the transceiver enters into an squelched state. The
input voltage should exceed ±300mV p-p for five bit times
max. (with alternating polarity) for unsquelching to occur.
In the Unsquelch state, the value of the threshold in the
comparator is reduced to take care of hysteresis effects.
While in the unsquelch state, the receive squelch circuit
looks for the SOI (Start of Idle) signal at the end of the
packet. When the SOI signal is detected, the receive
squelch is turned on again.
(c) Full Duplex Functions
The Full Duplex scheme allows the simultaneous transmission on the TPO ± and simultaneous reception on the
TPI ± without interruption, effectively doubling the bandwidth to 20 MBPS in switched network implementations on
10Base-T. The 80C25 can be made to operate either in the
AutoDUPLEX or in the Forced FullDuplex scheme according to Table 2.
(e) The Link integrity functions
The 80C25 monitors the TPI± pins continuously for valid
data and link pulse activity. If neither data nor link test pulse
is detected for a minimum time, the transceiver enters into
a Link Test Fail State and disables the transmitter, receiver, collision presence and the SQE functions. For the
transceiver to exit this state, it should receive three consecutive link pulses or valid data at the TPI ± inputs to
resume normal packet transmission and reception. Additionally, the transmitter generates link pulses periodically
when it's not transmitting data to indicate to the network
that the link is intact. Please refer to figure 14 for the
diagram illustrating the Transmit Link Pulse Voltage Tem-
Table 2. FDPLX Pin Description
FDPLX
1
float
0
MODE
Full Duplex Mode Enabled
AutoDUPLEX Enabled
Normal
6
MD400142/D
80C25
plate as specified in the IEEE 802.3. The Link Pulse Detect
Output and Link Pulse Disable Function are combined on
one pin, LNK_LED/LNK_DIS according to Table 3.
(i) Loopback functions
Loopback in the TP mode is internally enabled when
Manchester encoded data is transmitted on TPO ± and no
data is received on the TPI ± in order to simulate Coax
Ethernet behavior. When internal loopback is enabled, the
transmitted data is loopbacked into the RXD and sent to
the controller. The loopback function is disabled during
Link Fail State, Jabber State and during Full-Duplex Operation.
Table 3. LNK_LED/LNK_DIS Pin Description
LNK_LED/LNK_DIS
I/O
Function
1
Output
LinkPulseNotDetected
0
Output
LinkPulseDetected
Input
LinkTestFunctionDisabled
TietoGND2
(l) Signal Quality Error Test
The Signal Quality Error test is used to indicate a successful transmission (i,e A transmission without interruptions
such as Collision, jabber or Link failure) to the DTE.[1]
(f) The Start of Idle (SOI) pulse
The transmit SOI pulse is a positive pulse inserted at the
end of every transmission to signal the end and the start of
idle period to corresponding receivers. The output pulse is
also shaped by the transmit waveshaper to meet the pulse
requirements specified in IEEE 802.3. Please refer to
figure 13 for the Transmit Start Of Idle Pulse voltage
template diagram. The receiver detects the SOI pulse by
sensing the missing data transitions with the zero crossing
comparator. Once the SOI pulse is detected, another SOI
pulse is generated and sent to the Controller interface
outputs.
AUI Interface
The differential transmit output pair DO± sends the encoded data on to an external transceiver that is capable of
driving 50 meters of 78 ohm shielded AUI cable directly
with a jitter of 0.5 ns max. The receive input differential pair
DI± goes through the AUI squelch comparator and the
zero crossing comparator. The AUI squelch comparator
compares the input signals with fixed minimum and maximum values of -175 mv and -325 mv respectively, and
passes it on to the squelch circuit to determine data
validity. The zero crossing comparator senses the transition point of the input pair without introducing excess jitter
and passes the data to the phase locked loop of the
decoder. The CI+/CI- are the collision input pair signals
which expect a 5 Mhz or a 10 Mhz square wave from an
external transceiver.
(g) Automatic Polarity Correction
The 80C25 provides autopolarity detection and correction
functions for the twisted pair receiver peak detectors to
determine whether normal or inverted data is received
over the TPI ± pins. A polarity reversed condition is sensed
and corrected when four opposite link pulses are detected
without the expected polarity or if 3-4 frames are received
with a reversed start-of-idle.
Collisions
Collisions are generated when two stations contend for the
network at the same time, resulting in simultaneous
activity detected on the TPO ± and TPI ±. When this happens, COLL will be asserted indicating to the controller the
simultaneous transmission of two or more stations on the
network. CSN is also asserted during collision. For further
details about timing, refer to figures 7 and 8.
(h) Jabber functions
The jabber function detects abnormally long streams of
Manchester-encoded data on the TXD input with the help
of a Jabber detect circuit. The jabber circuit uses a Jabber
timer, which monitors the TXEN pin. It starts counting at
the beginning of each transmission. If the timer expires
before TXEN goes inactive, the 80C25 enters a jabber
state disabling the transmit/loopback functions and enabling the collision functions. If TXEN goes inactive before
the timer expires, the timer is reset and becomes ready for
the next transmission.
Note:
1. Since SQE is internally enabled on the 80C25, on successful transmission, a collision signal is presented to the controller as an
indication when the transmitter goes idle on the twisted pair network.
7
MD400142/D
80C25
Oscillator
Power Supply Decoupling
The internal clock generator is controlled either by an
external parallel resonant crystal connected across X1 &
GND2 , or by connecting a clock to the input pin X1. This
external 20 Mhz clock is used by the clock circuitry and the
PLL to generate a 10 Mhz ± 0.01% transmit clock. The
manchester encoding process uses both the 10Mhz and
20Mhz clocks.
There are two VCC's on the 80C25 (VCC1 and VCC2 ) and two
GND's (GND1 and GND2).
VCC1 and VCC2 should be connected together as close as
possible to the device with a large VCC plane.
GND1 and GND2 should also be connected together as
close as possible to the device with a large ground plane.
Crystal Specification:
1. Parallel resonant mode
2. Frequency ............. 20 MHz ±0.01% @ 0 – 70 °C
3. Equivalent Series Resistance ............ 25 Ω max.
4. Load Capacitance ............................. 20 pf max.
5. Case Capacitance .............................. 7 pf max.
A 0.1 µF decoupling capacitor should be connected
between VCC1 and GND1 as close as possible to the device
pins, preferably within 0.5". The same should be repeated
for VCC2 and GND2 .
Automatic Port Selection
The interface to the Manchester encoder can be selected
to be either TP, AUI or Autoport. Port selection is done with
the TP/AUI pin as described in Table 4.
Table 4. TP/AUI Pin Description
TP/AUI
Port
1
TP
float
Autoport
0
AUI
The Autoport mode automatically selects either the TP or
AUI port by detecting the presence or absence of activity
on the TPI± and DI± inputs. If autoport mode is selected,
the device powers up with TP port active. If no packets or
LINK pulses are detected on the TP port, the device
switches to AUI port. The device will stay in AUI mode as
long as no activity is detected on TP port.
8
MD400142/D
0.01
µF
TxO
RxI
RX–
RX+
CI–
CI+
TX–
TX+
a. Valor
b. Coilcraft
c. PCA
d. Bel Hybrids and Magnetics
e. FEE Fil-mag
f. NANO Pulse
3. Transformers are available from
PT4152
Q4430-A
EPE6047S
A553-1084-01
23Z435
000-6115-00
DI–
DI+
CI–
CI+
DO–
DO+
10
9
8
7
6
5
4
VCC1
1
15
80C25
16
20 MHZ
3
27
2
20
21
22
23
24
25
26
23 27 28 29
ETHERNET CONTROLLER
21 19 22 20
GND 1
2
CIS
TxD
TxEN
TPI–
TPI+
TPO–
TPO+
REXT
10 K
[3]
Figure 2. 80C25 in Typical TP/Coax Adapter Board Application
Tel: (619) 537-2500
Tel: (708) 639-6400
Tel: (818) 892-0761
Tel: (201) 432-0463
Tel: (619) 569-6577
Tel: (714) 529-2600
VCC
LNK_LED / LNK_DIS
2. This resistance value will meet the template requirements
specified on a no load condition. However, a capacitive or
inductive loading can influence the current level. Hence it may be
necessary to adjust the value to compensate the loading involved.
1. The EM2 is an Ethernet transceiver module with on
board isolation transformer and a DC-DC converter.
Notes:
1M
CDS
EM2
[2]
1K
VCC2
CSN
13
CSN
12
TxC
TxC
14
COLL
11
FDPLX_DET
ADUPLX
9
COLL
GND 2
X1
17
FDPLX
18
RxC
RxC
19
RxD
RxD
TP/AUI
TxD
0.1
µF
TxEN
V
CC
200Ω
MD400142/D
50Ω
200Ω
OPTIONAL
0.1µF
50Ω
0.1
µF
0.1µF
1:1
2CT:1
TRANSFORMER
RJ-45
6
3
2
1
[4]
80C25
80C25
Absolute Maximum Ratings
VCC1 , VCC2 Supply Voltage .......................... –0.3V to 7V
All Inputs and Outputs ..................... –0.3 to VCC + 0.3 V
Latchup Current ................................................ ±25 mA
Package Power Dissipation .................. 1 Watt @ 25°C
Storage Temperature ............................. –65 to +150°C
Operating Temperature .......................... –65 to +125°C
Lead Temperature (Soldering, 10 sec) ............... 250 °C
*COMMENT: Stresses above those listed under “Absolute
Maximum Ratings” may cause permanent damage to the
device. This is a stress rating only and functional operation
of the device at these or any other conditions above those
indicated in the operational sections of this specification is
not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Power Supply Characteristics
Test conditions are as follows:
1. T = 0 –70°C
2. VCC = 5V ±5%
3. 20 MHZ ±.01%
4. REXT = 10K, with no load.
Limit
Sym.
Parameter
ICC
VCC Power Supply
Current
Min
Typ
Max
Unit
Conditions
110
85
150
110
mA
mA
Transmitting, TP selected
Transmitting, AUI selected
Max
Unit
Conditions
0.8
Volt
All except X1, TP / AUI, FDPLX
0.8
Volt
TP / AUI, FDPLX
1.5
Volt
X1
VCC/2
+0.5 V
Volt
TP / AUI, FDPLX
DC Digital I/O Characteristics
Test conditions are as follows:
1. T = 0–70°C
2. VCC = 5V ±5%
3. 20 MHZ ±.01%
4. REXT = 10K, with no load.
Limit
Sym.
Parameter
VIL
Input Low Voltage
Min
Typ
VIM
Input Intermediate
Voltage
VCC/2
–0.5 V
VIH
Input High Voltage
2
Volt
All except X1, TP / AUI, FDPLX
VCC–0.8
Volt
TP/AUI, FDPLX
3.5
Volt
X1
VIL
Input Low Level
1.1
1.5
1.9
Volt
TP/AUI, FDPLX
IIH
Input High Current
15
60
120
µA
VIN= VCC
All Except LNK_LED/LNK_DIS
IIL
Input Low Current
–15
–60
–120
µA
VIN= GND
All Except CIS [1]
10
MD400142/D
80C25
DC Digital I/O Characteristics cont’d
Limit
Sym.
Parameter
VOL
Output Low Voltage
Min
Typ
Max
Unit
0.4
Volt
Conditions
IOL= 2.1 mA
FDPLX_DET, LNK_LED/LNK_DIS
1.2
Volt
IOL= –20 mA
LNK_LED/LNK_DIS
VOH
Output High Voltage
4
Volt
IOH= –1 mA
FDPLX_DET
CIN
Input Capacitance
5
pF
COUT
Output Capacitance
5
pF
Notes:
1. Not measured due to internal pull-down to GND.
11
MD400142/D
80C25
Twisted Pair Interface Characteristics
Unless otherwise specified, all test conditions are as follows:
1. T = 0–70°C
2. VCC = 5V ±5%
3. 20MHZ ±.01%
4. REXT = 10K, with no load.
5. 50 ohm load from TPO± to VCC
6. 10Mhz sine wave on TPI±
Limit
Sym.
Parameter
Min
Typ
Max
Unit
TOV
TPO± Differential Output
Voltage
2.2
2.5
2.8
Vpk
TOVT
TPO± Differential Output
Voltage Template
See Figure 12
TSOI
TPO± SOI Output
Voltage Template
See Figure 13
TLPT
TPO± Link Pulse Output
Voltage Template
See Figure 14
TOIV
TPO± Differential Output
Idle Voltage
±50
mV
TOIA
TPO± Output Current
44
50
56
mA pk
TOIR
TPO± Output Current
Adjustment Range
30
50
80
mA pk
TCMA
TPO± Common Mode
AC Output Voltage
10
50
mV pk
THD
TPO± Harmonic
Distortion
–27
dB
TOR
TPO± Output Resistance
TOC
TPO± Output
Capacitance
RST
TPI± Squelch
Threshold
310
540
mVpk
RUT
TPI± Unsquelch
Threshold
190
330
mVpk
RZT
TPI± Zero Cross
Switching Threshold
20
mVpk
ROCV
TPI± Input Open Circuit
Voltage
(VCC/3)+0.25
Volt
RCMR
TPI± Input Common
Mode Voltage Range
VCC/3+1.0
Volt
(VCC/3)–0.25
10K
ohms
15
pF
VCC/3
VCC/3–1.0
12
MD400142/D
Conditions
Measured on Secondary
Side of XFMR on Figure 2.
VCC = 5V Adjustable
with REXT
80C25
Twisted Pair Interface Characteristics cont’d
Limit
Sym.
Parameter
RDR
Min
Typ
Max
Unit
TPI+/– Input Differential
Voltage Range
VCC
Volt
RCRR
TPI+/– Input Common
Mode Rejection Ratio
–20
dB
RIR
TPI+/– Input Resistance
RIC
TPI+/– Input Capacitance
5K
ohm
10
13
MD400142/D
pF
Conditions
0–10Mhz
80C25
AUI Characteristics
Unless otherwise specified, all test conditions are as follows:
1. T = 0–70°C
2. VCC = 5V ±5%
3. 20 MHZ ±.01%
4. REXT = 10K with no load.
5. 78 ohm, 27µH load on DO±
6. 10 Mhz sine wave on DI±, CI±
Limit
Sym.
Parameter
Min
AOV
DO±, Differential
Output Voltage
550
AORF
DO±, Output Rise
And Fall Time
AOIV
Max
Unit
1200
mVpk
5
ns
DO±, Differential
Output Idle Voltage
±40
mV
AOVU
DO±, Differential
Output Voltage
Undershoot During Idle
–100
mV
AOCD
DO±, Common
Mode DC Output Voltage
VCC/2.1
Volt
AOCA
DO±, Common
Mode AC Output Voltage
40
mV pk
AOR
DO±, Output
Resistance
75
ohms
AOC
DO±, Output
Capacitance
AIST
DI±, CI± Squelch
Threshold
-175
-325
mV
AIUT
DI±, CI± Unsquelch
Threshold
-100
-225
mV
AIZT
DI±, CI± Zero Cross
Switching Threshold
20
mVpk
AIOC
DI±, CI± Input Open Circuit
Voltage
(VCC/2)–.25
(VCC/2)+.25
Volt
AICR
DI±, CI± Input Common
Mode Voltage Range
(VCC/2)–1.0
(VCC/2)+1.0
Volt
AIVR
DI±, CI± Input Differential
Voltage Range
0
VCC
Volt
AIR
DI±, CI± Input Resistance
5K
AIC
DI±, CI± Input Capacitance
VCC/3.5
Typ
VCC/3.0
15
VCC/2
10K
ohm
10
pF
14
MD400142/D
pF
Conditions
tR, tF measured at 10-90%
points
80C25
AC Test Timing Conditions
Unless otherwise specified, all test conditions for timing characteristics are as follows:
1. T = 0 – 70°C
2. VCC = 5v ±5%
3. 20MHZ ±.01%
4. REXT = 10K, with no load.
5. Input Conditions
All Inputs:
tR, tF< = 10ns from 20-80% points
6. Output Loading
TPO±:
50 ohms to VCC on each output, 10pF
DO±:
78 ohms differentially, 10pF
Open Drain Digital Outputs:
1K pullup, 50pF
All Other Digital Outputs:
50pF
7. Measurement Points
TPO±, TPI±, DO±, DI±, CI±:
Zero crossing during data and ±.3V point at start/end of signal
X1:
VCC/2
All other inputs and outputs:
1.5 Volts
20 MHZ Input Clock Timing Characteristics
Limit
Sym.
Parameter
t1
X1 Cycle Time
Min
Typ
Max
Unit
49.995
50.000
50.005
ns
Conditions
Refer to Figure 3 for timing diagram.
X1
t1
Figure 3. 20 MHZ Input Clock Timing
15
MD400142/D
80C25
Transmit Timing Characteristics
Parameter
Min
Limit
Typ
Max
Unit
t11
TXC Cycle Time
99.99
100
100.01
ns
t12
TXC High Time
40
60
ns
t13
TXC Low Time
40
60
ns
t14
TXC Rise Time
5
ns
t15
TXC Fall Time
5
ns
t16
TXEN Setup Time
30
ns
t17
TXEN Hold Time
0
ns
t18
TXD Setup Time
30
ns
t19
TXD Hold Time
0
t20
Transmit Bit Loss
2
Bits
TP and AUI
t21
Transmit Propagation
Delay
2
Bits
TP and AUI
t22
Transmit Output Jitter
8
ns
TP
0.5
ns
AUI
Sym.
t24
t25A
t25B
Transmit Output Rise
And Fall Time
Transmit SOI Pulse
Width to 0.3V Point
Transmit SOI Pulse
Width to 40 mV Point
ns
See Figure 12
ns
TP
ns
AUI
250
ns
TP
Measure TPO± from last
zero cross to 0.3V point.
200
ns
AUI
Measure DO± from last zero
cross to 0.3V point.
4500
ns
TP
Measure TPO± from last
zero cross to 40mV point.
7000
ns
AUI
Measure DO± from last zero
cross to 40 mV point.
5
Refer to Figure 4 for timing diagram.
16
MD400142/D
Conditions
80C25
t 12 t 13
SEEQ
t14
t15
TxC
t 16
t 11
t 17
TxEN
t19
t 18
TxD
B0
B1
B2
B3
t 21
t25b
t 25a
t 20
TPO±
or
DO±
B0
B0
B1
B1
B2
t 22
INTEL
B2
B3
t 24
SAME AS SEEQ EXCEPT TxEN IS INVERTED (ACTIVE LOW).
Figure 4. Transmit Timing
17
MD400142/D
B3
80C25
Receive Timing Characteristics
Limit
Sym.
Parameter
t31
CSN Assert Delay Time
Min
Typ
Max
Unit
Conditions
600
ns
TP
240
ns
AUI
t32
CSN Assert Setup Time
30
ns
t33
CSN Deassert Hold Time
20
40
ns
SEEQ Controller
10
35
ns
INTEL Controller
t35
RXC to RXD Setup Time
40
t36
RXC to RXD Hold Time
30
t38
RXD Propagation Delay
t39
RXC High Time
40
40
60
ns
INTEL Controller
t40
RXC Low Time
40
60
ns
SEEQ Controller
40
1500
ns
INTEL Controller, Start of Packet
40
250
ns
INTEL Controller, End of Packet
CSN Assert To RXC
Switchover From TX Clock
To RX Clock
1500
ns
TP
1500
ns
AUI
t42
CSN Deassert To RXC
Switchover From Rx Clock
To Tx Clock
200
ns
t43
SOI Pulse Width Required
For Idle Detection
125
200
ns
TP
Measure TPI± from last zero
cross to .3v point.
125
160
ns
AUI
Measure RX± from last zero
cross to .45v point.
±13.5
ns
Data
±8.5
ns
Preamble
10
ns
t41
t44
Receive Input Jitter
t49
RXC, RXD, CSN Output
Rise And Fall Times
ns
ns
200
ns
200
ns
SEEQ Controller
Refer to Figures 5 and 6 for timing diagram.
NOTES:
1.
2.
3.
4.
CI+ and CI– asserts and deasserts COLL, asynchronously, and asserts and deasserts CSN synchronously with RxC.
If CI+ and CI– arrives within 4.5 µs from the time CSN was deasserted; CSN will not be reasserted (on transmission node only).
When CI+ and CI– terminates, CSN will not be deasserted if DI± are still active.
When the node finishes transmitting and CSN is deasserted, it cannot be asserted again for 4.5 µs.
18
MD400142/D
80C25
SEEQ
1
0
1
0
1
0
1
0
1
0
TPI±
or
DI±
t 31
t 44
CSN
t41
t 39
t 32
Tx
RxC
t 38
Tx
t40
Tx
Rx
Rx
Rx
Rx
t36
t35
RxD
Rx
1
0
1
0
Figure 5a. Receive Timing — Start of Packet for SEEQ’s Controllers
INTEL
1
TPI±
or
DI±
0
1
0
1
0
1
0
1
0
1
Rx
Rx
t31
t44
CSN
t 41
t 40
t 32
RxC
Tx
Tx
t38
t39
Rx
Tx
Rx
t35
0
RxD
Rx
Rx
t36
1
0
1
NOTE:
SAME AS SEEQ EXCEPT CSN IS INVERTED (ACTIVE LOW), RxC IS INVERTED (FALLING EDGE TRIGGERED), RxC IS
SHUTOFF DURING t 41 ACQUISITION TIME, RxD IS HIGH DURING t 41 ACQUISITION TIME AND DURING IDLE TIME.
Figure 5b. Receive Timing — Start of Packet for Intel’s Controllers
19
MD400142/D
0
1
80C25
SEEQ
B N–2
TPI±
or
DI±
B N–1
SOI
BN
t 43
CSN
t 42
t39
t 33
RxC
Rx
Rx
B N–5
RxD
Rx
B N–4
Rx
B N–3
Rx
B N–2
Rx
B N–1
t 40
Rx
Tx
BN
Figure 6a. Receive Timing — End of Packet for SEEQ’s Controllers.
INTEL
B N-2
B N-1
BN
SOI
TPI±
or
DI±
t 43
CSN
t 42
t 40
t33
RxC
Rx
Rx
B N-5
RxD
Rx
B N-4
Rx
B N-3
Rx
Rx
B N-2
B N-1
t39
Tx
Tx
Tx
BN
NOTE:
SAME AS SEEQ EXCEPT TxEN IS INVERTED (ACTIVE LOW), RxC IS INVERTED RxC IS SHUTOFF DURING
t 41 ACQUISITION TIME, RxD IS HIGH DURING t 41 ACQUISITION TIME, REFER TO FIGURE 6a.
Figure 6b. Receive Timing — End of Packet for Intel’s Controllers.
20
MD400142/D
Tx
80C25
Collision Timing Characteristics
Sym.
Parameter
t51
COLL Assert Delay Time Rcv After Xmt
t52
t53
t54
Min
Limit
Typ
COLL Assert Delay Time Xmt After Rcv
COLL Deassert Delay
Time - Rcv After Xmt
COLL Deassert Delay
Time - Xmt After Rcv
Max
Unit
600
ns
TP
TPI± to COLL
300
ns
AUI
CI± to COLL
600
ns
TP
TPO± to COLL
300
ns
AUI
CI± to COLL
500
ns
TP
TPI± to COLL
500
ns
AUI
CI± to COLL
500
ns
TP
TPO± to COLL
500
ns
AUI
CI± to COLL
10
ns
t55
COLL Rise And Fall Time
t56
CI± Cycle Time
80
117
ns
t57
CI± Low Or High Time
35
70
ns
t58
CI± Rise And Fall Time
10
ns
Refer to Figures 7 and 8 for timing diagram.
21
MD400142/D
Conditions
80C25
SEEQ
TPO±
or
DO±
TPI±
(TP Only)
t 57
t 57
CI±
(AUI Only)
t
t 51
t
t 56
t51
53
58
t 58
t 53
COLL
t55
INTEL
t55
SAME AS SEEQ EXCEPT COLL IS INVERTED (ACTIVE LOW)
Figure 7. Collision Timing — Receive After Transmit
SEEQ
SEEQ
TPI±
or
DI±
TPO±
(TP Only)
t
57
t
57
CI±
(AUI Only)
t
t 52
t
56
t52
54
t 58
t58
t
54
COLL
t
INTEL
t 55
55
SAME AS SEEQ EXCEPT COLL IS INVERTED (ACTIVE LOW)
Figure 8. Collision Timing — Transmit After Receive
22
MD400142/D
80C25
Link Pulse Timing Characteristics
Min
Limit
Typ
Sym.
Parameter
Max
Unit
t61
Transmit Link Pulse Width
75
125
ns
t62
Transmit Link Pulse Period
11
15
ms
t63
Transmit Link Pulse To
Double Link Pulse Spacing
5.0
5.4
µs
Full Duplex Mode Signalling
t64
Transmit Double Link
Pulse Interval Spacing
16
16
Link
Pulses
Full Duplex Mode Signalling
t65
Receive Link Pulse Width
Required For Detection
35
200
ns
t66
Receive Link Pulse
Minimum Period Required
For Detection
2
7
ms
Link_Test_Min
t67
Receive Link Pulse
Maximum Period Required
For Detection
50
150
ms
Link_Loss and
Link_Test_Max
t68
Receive Link Pulse To
Double Link Pulse Spacing
Required For Full Duplex
Mode Detection
4.8
5.6
µs
Full Duplex Mode Detection
t69
Receive Double Link
Pulse Minimum Period
Required For Full Duplex
Mode Detection
204
216
ms
Full Duplex Mode Detection
t70
Receive Double Link Pulse
Maximum Period Required
for Full Duplex Detection
750
850
ms
Full Duplex Detection Mode
t71
Receive Link Pulse Assert
2
10
Link
Pulses
t72
Receive Full Duplex Assert
7
µs
5.2
4
210
3
Refer to Figure 9 for timing diagram.
23
MD400142/D
Conditions
Full Duplex Mode Detection
80C25
TRANSMIT
16th
1st
2nd
16th
TPO±
t63
t61
t 62
t62
t 64
RECEIVE
TPI±
t68
t65
t 66
t66
t67
LNK_LED
t 69
t 70
t 72
FDPLX_DET
Figure 9. Link Pulse Timing
24
MD400142/D
t 71
80C25
Jabber Timing Characteristics
Limit
Sym.
Parameter
Min
t81
Jabber Activation Time
t82
Jabber Deactivation Time
Typ
Max
Unit
Conditions
40
60
ms
TP and AUI
400
430
ms
TP and AUI
Refer to Figure 10 for timing diagram
SEEQ
ALL TIMING TO MIDDLE OF WAVEFORM
TxEN
t81
TPO±
DO±
t 82
t81
COLL
t81
CSN
INTEL
SAME AS SEEQ EXCEPT COLL IS INVERTED (ACTIVE LOW), CSN IS INVERTED, AND TxEN IS INVERTED.
Figure 10. Jabber Timing
25
MD400142/D
80C25
Loopback/SQE Timing Characteristics
Limit
Sym.
Parameter
Min
t93
SQE Pulse Delay
t94
SQE Pulse Width
Typ
Max
Unit
600
700
ns
750
850
ns
Conditions
Refer to Figure 11 for timing diagram.
b. SQE TEST TIMING
TxEN
CSN
t 93
COLL
INTEL
SAME AS SEEQ EXCEPT TxEN INVERTED, CSN INVERTED
Figure 11. SQE Test Timing
26
MD400142/D
t 94
80C25
1.0
0.8
VOLTAGE (V)
0.6
0.4
0.2
0.0
–0.2
–0.4
–0.6
–0.8
–1.0
0
10
20
30
40
50
60
70
80
90
TIME (ns)
Figure 12. Twisted Pair Output Voltage Template with Line Model.
27
MD400142/D
100
110
80C25
0 BT
4.5 BT
3.1 V
0.5 V/ns
0.25 BT
2.25 BT
585 mV
6.0 BT
+50 mV
–50 mV
45.0 BT
585 mV sin(2 * * (t/1BT))
0 t 0.25 BT and
2.25 t 2.5 BT
–3.1 V
2.5 BT
4.5 BT
With and Without Line Model
Figure 13. Transmit Start of Idle Pulse Voltage Template
1.3 BT
0 BT
3.1 V
0.5 V/ns
585 mV
0.5 BT
0.6 BT
2.0 BT
300 mV
4.0 BT
+50 mV
+50 mV
–50 mV
200 mV
0.25 BT
585 mV sin(2 *
0.25 BT
t
–50 mV
4.0 BT
* (t/1BT –.25))
0.5 BT
585 mV sin(2 *
0.6 BT
t
* (t/1BT –.35))
0.85 BT
–3.1 V
0.85 BT
2.0 BT
With and Without Line Model
Figure 14. Transmit Link Pulse Voltage Template
28
MD400142/D
42.0 BT
80C25
Ordering Information
PART NUMBER
N
Q
80C25
PRODUCT: 80C25 (SEEQ and INTEL Controller Modes)
TEMPERATURE RANGE: = 0° to 70° C
PACKAGE TYPE : N = 28 PIN PLCC
SEEQ Full Duplex Designation
Full Duplex
Symbol indentifies product as
Full Duplex device.
Revision History
5/8/96
- All references to separate ‘digital’ and ‘analog’ power and grounds deleted.
- Page 3, Pin Descriptions: Pin 17 (X1) description clarified.
- Page 8, Added Power Supply Decoupling Suggestions.
- Page 10, Digital I/O Characteristics:
- Added VIH and VIL specifications for TP/AUI and FDPLX.
- Added VIM (Input Intermediate Voltage) specifications.
- VOL (max) changed to 1.2 V.
- IIL for CIS pin spec clarified (see note at table bottom).
- IIH (min) changed from 30 µA to 15 µA.
- IIL (min) changed from –30 µA to –15 µA.
- Page 14, AUI Characteristics:
- AOCD (max) changed from VCC/2.5 to VCC/2.1.
9/9/96
- Page 30, Dimension diagram has been added to this data sheet.
12/10/96
- Page 16, Transmit Timing Charateristics, TXEN Hold Time (min.) has been changed from 40 to 0.
29
MD400142/D
80C25
Surface Mount Packages
28-Pin Plastic Leaded Chip Carrier Type N
.048 (1.22) x 45°
.042 (1.07) x 45°
PIN NO. 1 IDENTIFIER
.300 (7.62)
REF
PIN NO. 1
.495 (12.57)
.485 (12.32)
.300 (7.62)
REF
.456 (11.58)
.450 (11.43)
.456 (11.58)
.450 (11.43)
.050 (1.27)
BSC
.495 (12.57)
.485 (12.32)
.056 (1.42)
.042 (1.07)
.0103 (0.261)
.0097 (0.246)
.180 (4.57)
.165 (4.19)
.110 (2.79)
.099 (2.52)
.021 (.53)
.013 (.33)
R .045 (1.14)
R .025 (.64)
.430 (10.92)
.390 (9.91)
Notes
1. All dimensions are in inches and (millimeters).
2. Dimensions do not include mold flash. Maximum allowable flash is .008 (.20).
3. Formed leads shall be planar with respect to one another within 0.004 inches.
30
MD400142/D
.020 (.51) Min.