DS3883A
BTL 9-Bit Data Transceiver
General Description
The DS3883A is one in a series of transceivers designed
specifically for the implementation of high performance Fu-
turebus+ and proprietary bus interfaces. The DS3883A, is a
BTL 9-bit Transceiver designed to conform to IEEE 1194.1
(Backplane Transceiver Logic -- BTL) as specified in the
IEEE 896.2 Futurebus+ specification. Utilization of the
DS3883A simplifies the implementation of byte wide
address/data with parity lines and also may be used for the
Futurebus+ status, tag and command lines.
The DS3883A driver output configuration is an NPN open
collector which allows Wired-OR connection on the bus.
Each driver output incorporates a Schottky diode in series
with its collector to isolate the transistor output capacitance
from the bus thus reducing the bus loading in the inactive
state. The combined output capacitance of the driver and re-
ceiver input is less than 5 pF. The driver also has high sink
current capability to comply with the bus loading require-
ments defined within IEEE 1194.1 BTL specification.
Backplane Transceiver Logic (BTL) is a signaling standard
that was invented and first introduced by National Semicon-
ductor, then developed by the IEEE to enhance the perfor-
mance of backplane buses. BTL compatible transceivers
feature low output capacitance drivers to minimize bus load-
ing, a 1V nominal signal swing for reduced power consump-
tion and receivers with precision thresholds for maximum
noise immunity. BTL eliminates settling time delays that se-
verely limit TTL bus performance, and thus provide signifi-
cantly higher bus transfer rates. The backplane bus is in-
tended to be operated with termination resistors (selected to
match the bus impedance) connected to 2.1V at both ends.
The low voltage is typically 1V.
Separate ground pins are provided for each BTL output to
minimize induced ground noise during simultaneous switch-
ing.The unique driver circuitry meets the maximum slew rate
of 0.5 V/ns which allows controlled rise and fall times to re-
duce noise coupling to adjacent lines.The transceiver's con-
trol and driver inputs are designed with high impedance PNP
input structures and are fully TTL compatible.
The receiver is a high speed comparator that utilizes a band-
gap reference for precision threshold control allowing maxi-
mum noise immunity to the BTL 1V signaling level. Separate
QV
CC
and QGND pins are provided to minimize the effects
of high current switching noise. The output is TRI-STATE
and fully TTL compatible.
The DS3883A supports live insertion as defined in 896.2
through the LI (Live Insertion) pin. To implement live inser-
tion the LI pin should be connected to the live insertion
power connector. If this function is not supported the LI pin
must be tied to the V
CC
pin. The DS3883A also provides
glitch free power up/down protection during power sequenc-
ing.
The DS3883A has two types of power connections in addi-
tion to the LI pin. They are the Logic V
CC
(V
CC
) and the Quiet
V
CC
(QV
CC
). There are two logic V
CC
pins on the DS3883
that provide the supply voltage for the logic and control cir-
cuitry. Multiple power pins reduce the effects of package in-
ductance and thereby minimize switching noise. As these
pins are common to the V
CC
bus internal to the device, a
voltage delta should never exist between these pins and the
voltage difference between V
CC
and QV
CC
should never ex-
ceed
0.5V because of ESD circuitry.
Additionally, the ESD circuitry between the V
CC
pins and all
other pins except for BTL I/O's and LI pins requires that any
voltage on these pins should not exceed the voltage on V
CC
+ 0.5V.
There are three different types of ground pins on the
DS3883A. They are the logic ground (GND), BTL grounds
(B0GNDB8GND) and the Bandgap reference ground
(QGND). All of these ground reference pins are isolated
within the chip to minimize the effects of high current switch-
ing transients. For optimum performance the QGND should
be returned to the connector through a quiet channel that
does not carry transient switching current. The GND and
B0GNDB8GND should be connected to the nearest back-
plane ground pin with the shortest possible path.
Since many different grounding schemes could be imple-
mented and ESD circuitry exists on the DS3883, it is impor-
tant to note that any voltage difference between ground pins,
QGND, GND or B0GNDB8GND should not exceed
0.5V
including power-up/down sequencing.
When CD (Chip Disable) is high, An and Bn are in a high im-
pedance state. To transmit data (An to Bn) the T/R signal is
high. To receive data (Bn to An) the T/R signal is low.
Features
n
9-bit Inverting BTL transceiver meets IEEE 1194.1
standard on Backplane Transceiver Logic (BTL)
n
Supports live insertion
n
Glitch free power-up/down protection
n
Typically less than 5 pF bus-port capacitance
n
Low bus-port voltage swing (typically 1V) at 80 mA
n
Open collector bus-port output allows Wired-OR
n
Controlled rise and fall time to reduce noise coupling
n
TTL compatible driver and control inputs
n
Built in bandgap reference with separate QV
CC
and
QGND pins for precise receiver thresholds
n
Exceeds 2 kV ESD (Human Body Model)
n
Individual bus-port ground pins minimize ground bounce
n
Tight skew (1 ns typical)
TRI-STATE
is a registered trademark of National Semiconductor Corporation.
July 1998
DS3883A
BTL
9-Bit
Data
T
ransceiver
1999 National Semiconductor Corporation
DS010719
www.national.com
Connection Diagram
DS010719-17
Order Number DS3883AVF
See NS Package Number VF44B
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2
Absolute Maximum Ratings
(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage
6.5V
Control Input Voltage
6.5V
Driver Input and Receiver Output
5.5V
Receiver Input Current
15 mA
Bus Termination Voltage
2.4V
Power Dissipation at 25C
PQFP (VF44B)
1.3W
Derate PQFP Package (VF44B)
11.1 mW/C
Storage Temperature Range
-65C to +150C
Lead Temperature
(Soldering, 4 seconds)
260C
Recommended Operating
Conditions
Min
Max
Units
Supply Voltage, V
CC
4.5
5.5
V
Bus Termination Voltage (V
T
)
2.06
2.14
V
Operating Free Air Temperature
0
70
C
DC Electrical Characteristics
(Notes 2, 3)
T
A
= 0C to +70C, V
CC
= 5V
10%
Symbol
Parameter
Conditions
Min
Typ
Max
Units
DRIVER AND CONTROL INPUT (CD, T/R , An)
V
IH
Minimum Input High Voltage
2.0
V
V
IL
Maximum Input Low Voltage
0.8
V
I
I
Input Leakage Current
V
IN
= V
CC
= 5.5V
250
A
I
IH
Input High Current
V
IN
= 2.4V, AN = CD = 0.5V, T/R = 2.4V
40
A
I
IL
Input Low Current
V
IN
= 0.5V, AN = CD = 0.5V, T/R = 2.4V
-100
A
V
CL
Input Diode Clamp Voltage
I
CLAMP
= -12 mA
-1.2
V
DRIVER OUTPUT/RECEIVER INPUT (Bn)
V
OLB
Output Low Bus Voltage
An = T/R = 2.4V, CD = 0.5V
0.75
1.0
1.1
V
(Note 5)
I
OL
= 80 mA
I
OFF
Output Off Low Current
An = 0.5V, T/R = 2.4V, Bn = 0.75V, CD = 0.5V
-200
A
Output Off High Current
An = 0.5V, T/R = 2.4V, Bn = 2.1V, CD = 0.5V
200
A
Output Off Low Current --
An = 0.5V, T/R = CD = 2.4V, Bn = 0.75V
-50
A
Chip Disabled
Output Off Low Current --
An = 0.5V, T/R = CD = 2.4V, Bn = 2.1V
50
A
Chip Disabled
V
TH
Receiver Input Threshold
T/R = CD = 0.5V
1.47
1.55
1.62
V
V
CLP
Positive Clamp Voltage
V
CC
= Max or 0V, I
Bn
= 1 mA, CD = T/R = 0V
2.4
3.4
4.5
V
An = 0V
V
CC
= Max or 0V, I
Bn
= 10 mA, CD = T/R = 0V
2.9
3.9
5.0
V
An = 0V
V
CLN
Negative Clamp Voltage
I
CLAMP
= -12 mA, CD = T/R = 0.5V
-1.2
V
RECEIVER OUTPUT (An)
V
OH
Voltage Output High
Bn = 1.1V, T/R = CD = 0.5V, I
OH
= -2 mA
2.4
3.2
V
V
OL
Voltage Output Low
T/R = CD = 0.5V, Bn = 2.1V, I
OL
= 24 mA
0.35
0.5
V
T/R = CD = 0.5V, Bn = 2.1V, I
OL
= 8 mA
0.35
0.4
V
I
OZ
TRI-STATE Leakage Current
An = 2.4V, CD = 2.4V, T/R = 0.5V
10
A
An = 0.5V, CD =2.4V, T/R = 0.5V
-10
A
I
OS
Output Short Circuit Current
Bn = 1.1V, T/R = CD = 0.5V (Note 4)
-40
-70
-100
mA
SUPPLY CURRENT
I
CC
Supply Current: Includes
T/R = All An Inputs = 2.4V, CD = 0.5V
62
mA
V
CC
, QV
CC
and LI
CD = T/R = 0.5V, All Bn Inputs = 2.1V
53
mA
I
LI
Live Insertion Current
T/R = CD = An = 0.5V, Bn = Open,
2.2
mA
V
CC
= QV
CC
= 5.5V
T/R = All An = 2.4V, CD = 0.5V, Bn = Open
4.5
mA
V
CC
= QV
CC
= 5.5V
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3
DC Electrical Characteristics
(Notes 2, 3) (Continued)
Note 1: "Absolute Maximum Ratings" are those beyond which the safety of the device cannot be guaranteed. They are not meant to imply that the device should
be operated at these limits. The table of "Electrical Characteristics" provides conditions for actual device operation.
Note 2: All input and/or output pins shall not exceed V
CC
+ 0.5V and shall not exceed the absolute maximum rating at any time, including power-up and power-down.
This prevents the ESD structure from being damaged due to excessive currents flowing from the input and/or output pins to QV
CC
and V
CC
. There is a diode between
each input and/or output to V
CC
which is forward biased when incorrect sequencing is applied. LI and Bn pins do not have power sequencing requirements with re-
spect to V
CC
and QV
CC
.
Note 3: All currents into device pins are positive; all currents out of device pins are negative. All voltages are referenced to device ground unless otherwise specified.
All typical values are specified under these conditions: V
CC
= 5V and T
A
= 25C, unless otherwise stated.
Note 4: Only one output should be shorted at a time, and duration of the short should not exceed one second.
Note 5: Referenced to appropriate signal ground. Do not exceed maximum power dissipation of package.
AC Electrical Characteristics
(Note 6)
T
A
= 0C to +70C, V
CC
= 5V
10%
Symbol
Parameter
Conditions
Min
Typ
Max
Units
DRIVER
t
PHL
An to Bn
Propagation Delay
CD = 0V, T/ R = 3V
1
3.5
6
ns
t
PLH
(
Figure 1 and Figure 2)
1
3.5
6
ns
t
PHL
CD to Bn
Enable Time
T/R = An = 3V
3
6
9
ns
t
PLH
Disable Time
(
Figure 1 and Figure 3 )
2.5
5
8
ns
t
PHL
T/R to Bn
Enable Time
(
Figure 8 and Figure 9)
9
13.5
18
ns
t
PLH
Disable Time
CD = 0V
2
6
10
ns
t
r
Transition Time -- Rise/Fall
(
Figure 1 and Figure 2)
1
2.5
4.5
ns
t
f
20% to 80%
CD = 0V, T/R = 3V (Note 10)
1
2
4.5
ns
SR
Slew Rate is Calculated
(
Figure 1 and Figure 2) (Note 10)
0.5
V/ns
from 1.3V to 1.8V
CD = 0V T/R = 3V
t
SKEW
An to Bn Skew (Same Package)
(Note 7)
1
3.5
ns
RECEIVER
t
PHL
Bn to An
CD = T/ R = 0V
2
4
7
ns
t
PLH
(
Figure 4 and Figure 5 )
1.5
4.5
7.5
ns
t
PLZ
CD to An
Disable Time
Bn = 2.1V, T/R = 0V
4
8
12
ns
t
PZL
Enable Time
(
Figure 6 and Figure 7 )
2.5
6
9
ns
t
PHZ
Disable Time
Bn = 1.1V, T/R = 0V
3
6.5
10
ns
t
PZH
Enable Time
(
Figure 6 and Figure 7 )
2
6
10
ns
t
PLZ
T/R to An
Disable Time
CD = 0V Bn = 2.1V
3
7
12
ns
t
PZL
Enable Time
(
Figure 8 and Figure 9 )
4
10
16
ns
t
PHZ
Disable Time
Bn = 1.1V, CD = 0V
2
6.5
10
ns
t
PZH
Enable Time
(
Figure 6 and Figure 7 )
3
7
11
ns
t
SKEW
Bn to An Skew (Same Package)
(Note 7)
1
3.5
ns
PARAMETERS NOT TESTED
C
output
BTL Output Capacitance
(Note 8)
5
pF
t
NR
Noise Rejection
(Note 9)
1
ns
Note 6: Input waveforms shall have a rise/fall time of 3 ns. Propagation delays are measured with a single output switching.
Note 7: t
SKEW
is an absolute value defined as differences seen in propagation delays between drivers in the same package with identical load conditions.
Note 8: The parameter is tested using TDR techniques described in 1194.0 BTL backplane Design Guide.
Note 9: This parameter is tested during device characterization. The measurement revealed that the part will reject 1 ns pulse widths.
Note 10: Futurebus+ transceivers are required to limit bus signal rise and fall times to no faster than 0.5 V/ns, measured between 1.3V and 1.8V (approximately 20%
to 80% of nominal voltage swing). The rise and fall times are measured with a transceiver loading equivalent to 12.5
tied to +2.1V DC.
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4
Pin Description
Pin Name
Number
Input/
Description
of Pins
Output
A0A8
9
I/O
TTL TRI-STATE receiver output and driver input
B0B8
9
I/O
BTL receiver input and driver output
B0GNDB8GND
9
NA
Parallel driver grounds reduce ground bounce due to high current
switching of driver outputs. (Note 11)
CD
1
I
Chip Disable
GND
2
NA
Ground for switching circuits. (Note 11)
LI
1
NA
Power supply for live insertion. Boards that require live insertion should
connect LI to the live insertion pin on the connector. (Note 12)
NC
8
NA
No Connect
QGND
1
NA
Ground for receiver input bandgap reference and non-switching circuits.
(Note 11)
QV
CC
1
NA
V
CC
supply for bandgap reference and non-switching circuits. (Note 12)
T/R
1
I
Transmit/Receive -- transmit (An to Bn), receive (Bn to An)
V
CC
2
NA
V
CC
supply for switching circuits. (Note 12)
Note 11: The multiplicity of parallel ground paths reduces the effective inductance of bonding wires and leads, which then reduces the noise caused by transients
on the ground path. The various ground pins can be tied together provided that the external ground has low inductance. (i.e., ground plane with power pins and many
signal pins connected to the backplane ground.) If the external ground floats considerably during transients, precautionary steps should be taken to prevent QGND
from moving with reference to the backplane ground. The receiver threshold should have the same ground reference as the signal coming from the backplane. A volt-
age offset between their grounds will degrade the noise margin.
Note 12: The same considerations for ground are used for V
CC
in reducing lead inductance (see (Note 11) ). QV
CC
and V
CC
should be tied together externally. If
live insertion is not supported, the LI pin can be tied together with QV
CC
and V
CC
.
CD
T/R
An
Bn (BTL)
H
X
Z
H
L
L
L
H
L
L
H
L
L
H
H
L
L
H
L
H
X = High or low logic state
Z = High impedance state
L = Low state
H = High state
Package Thermal Characteristics
Linear Feet per
Minute Air Flow
(LFPM)
JA
(C/W)
44-Pin
PQFP
0
82
225
68
500
60
900
53
Note 13: The above values are typical values and are different from the Ab-
solute Maximum Rating values, which include guardbands.
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