DS8922/DS8922A/DS8923A TRI-STATE
RS-422 Dual Differential Line Driver and Receiver Pairs
General Description
The DS8922/22A and DS8923A are Dual Differential Line
Driver and Receiver pairs. These devices are designed spe-
cifically for applications meeting the ST506, ST412 and
ESDI Disk Drive Standards. In addition, the devices meet the
requirements of the EIA Standard RS-422.
These devices offer an input sensitivity of 200 mV over a
7V common mode operating range. Hysteresis is incorpo-
rated (typically 70 mV) to improve noise margin for slowly
changing input waveforms. An input fail-safe circuit is pro-
vided such that if the receiver inputs are open the output as-
sumes the logical one state.
The DS8922A and DS8923A drivers are designed to provide
unipolar differential drive to twisted pair or parallel wire trans-
mission lines. Complementary outputs are logically ANDed
and provide an output skew of 0.5 ns (typ.) with propagation
delays of 12 ns.
Both devices feature TRI-STATE outputs. The DS8922/22A
have independent control functions common to a driver and
receiver pair. The DS8923A has separate driver and receiver
control functions.
Power up/down circuitry is featured which will TRI-STATE
the outputs and prevent erroneous glitches on the transmis-
sion lines during system power up or power down operation.
The DS8922/22A and DS8923A are designed to be compat-
ible with TTL and CMOS.
Features
n
12 ns typical propagation delay
n
Output skew --
0.5 ns typical
n
Meets the requirements of EIA Standard RS-422
n
Complementary Driver Outputs
n
High differential or common-mode input voltage ranges
of
7V
n
0.2V receiver sensitivity over the input voltage range
n
Receiver input fail-safe circuitry
n
Receiver input hysteresis -- 70 mV typical
n
Glitch free power up/down
n
TRI-STATE outputs
Connection Diagrams
TRI-STATE
is a registered trademark of National Semiconductor Corp.
DS8922A Dual-In-Line
DS008511-1
Order Number DS8922M, DS8922N,
DS8922AM or DS8922AN
See NS Package Number M16A or N16E
June 1998
DS8922/DS8922A/DS8923A
TRI-ST
A
T
E
RS-422
Dual
Differential
Line
Driver
and
Receiver
Pairs
1998 National Semiconductor Corporation
DS008511
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Connection Diagrams
(Continued)
Truth Tables
DS8922/22A
EN1
EN2
RO1
RO2
DO1
DO2
0
0
ACTIVE
ACTIVE
ACTIVE
ACTIVE
1
0
HI-Z
ACTIVE
HI-Z
ACTIVE
0
1
ACTIVE
HI-Z
ACTIVE
HI-Z
1
1
HI-Z
HI-Z
HI-Z
HI-Z
DS8923A
DEN
REN
RO1
RO2
DO1
DO2
0
0
ACTIVE
ACTIVE
ACTIVE
ACTIVE
1
0
ACTIVE
ACTIVE
HI-Z
HI-Z
0
1
HI-Z
HI-Z
ACTIVE
ACTIVE
1
1
HI-Z
HI-Z
HI-Z
HI-Z
DS8923A Dual-In-Line
DS008511-2
Order Number DS8923AM, DS8923AN,
See NS Package Number M16A or N16E
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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
7V
Drive Input Voltage
-0.5V to +7V
Output Voltage
5.5V
Receiver Output Sink Current
50 mA
Receiver Input Voltage
10V
Differential Input Voltage
12V
Maximum Package Power Dissipation
@
+25C
M Package
1300 mW
N Package
1450 mW
Derate M Package 10.4 mW/C above +25C
Derate N Package 11.6 mW/C above +25C
Storage Temperature Range
-65C to +165C
Lead Temp. (Soldering, 4 seconds)
260C
Recommended Operating
Conditions
Min
Max
Units
Supply Voltage
4.5
5.5
V
Temperature (T
A
)
0
70
C
DS8922/22A and DS8923A Electrical Characteristics
(Notes 2, 3, 4)
Symbol
Conditions
Min
Typ
Max
Units
RECEIVER
V
TH
-7V
V
CM
+7V
-200
35
+200
mV
V
HYST
-7V
V
CM
+7V
15
70
mV
R
IN
V
IN
= -7V, +7V (Other Input = GND)
4.0
6.0
k
I
IN
V
IN
= 10V
3.25
mA
V
IN
= -10V
-3.25
mA
V
OH
V
CC
= MIN, I
OH
= - 400 A
2.5
V
V
OL
V
CC
= MAX, I
OL
= 8 mA
0.5
V
I
SC
V
CC
= MAX, V
OUT
= 0V
-15
-100
mA
DRIVER
V
OH
V
CC
= MIN, I
OH
= -20 mA
2.5
V
V
OL
V
CC
= MIN, I
OL
= +20 mA
0.5
V
I
OFF
V
CC
= 0V, V
OUT
= 5.5V
100
A
|VT|| VT |
0.4
V
VT
2.0
V
|V
OS
V
OS
|
0.4
V
I
SC
V
CC
= MAX, V
OUT
= 0V
-30
-150
mA
DRIVER and RECEIVER
I
OZ
V
OUT
= 2.5V
50
A
TRI-STATE
V
CC
= MAX
V
OUT
= 0.4V
-50
A
Leakage
I
CC
V
CC
= MAX
ACTIVE
76
mA
TRI-STATE
78
mA
DRIVER and ENABLE INPUTS
V
IH
2.0
V
V
IL
0.8
V
I
IL
V
CC
= MAX, V
IN
= 0.4V
-40
-200
A
I
IH
V
CC
= MAX, V
IN
= 2.7V
20
A
I
I
V
CC
= MAX, V
IN
= 7.0V
100
A
V
CL
V
CC
= MIN, I
IN
= -18 mA
-1.5
V
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3
Receiver Switching Characteristics
(
Figures 1, 2, 3)
Parameter
Conditions
Min
Typ
Max
Units
8922
8922A/23A
T
pLH
CL = 30 pF
12
22.5
20
ns
T
pHL
CL = 30 pF
12
22.5
20
ns
|T
pLH
T
pHL
|
CL = 30 pF
0.5
5
3.5
ns
Skew (Channel to Channel)
CL = 30 pF
0.5
3.0
2.0
ns
T
pLZ
CL = 15 pF S2 Open
15
ns
T
pHZ
CL = 15 pF S1 Open
15
ns
T
pZL
CL = 30 pF S2 Open
20
ns
T
pZH
CL = 30 pF S1 Open
20
ns
Driver Switching Characteristics
Parameter
Conditions
Min
Typ
Max
Units
8922
8922A/23A
SINGLE ENDED CHARACTERISTICS (
Figures 4, 5, 6, 8)
T
pLH
CL = 30 pF
12
15
15
ns
T
pHL
CL = 30 pF
12
15
15
ns
T
TLH
CL = 30 pF
5
10
10
ns
T
THL
CL = 30 pF
5
10
10
ns
|T
pLH
T
pHL
|
CL = 30 pF
0.5
ns
Skew
CL = 30 pF (Note 5)
0.5
5
3.5
ns
Skew (Channel to Channel)
0.5
3.0
2.0
ns
T
pLZ
CL = 30 pF
15
ns
T
pHZ
CL = 30 pF
15
ns
T
pZL
CL = 30 pF
20
ns
T
pZH
CL = 30 pF
20
ns
DIFFERENTIAL SWITCHING CHARACTERISTICS (Note 6), (
Figure 4)
T
pLH
CL = 30 pF
12
15
15
ns
T
pHL
CL = 30 pF
12
15
15
ns
|T
pLH
T
pHL
|
CL = 30 pF
0.5
6.0
2.75
ns
Note 1: "Absolute Maximum Ratings" are those values 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 currents into device pins are shown as positive values; all currents out of the device are shown as negative; all voltages are referenced to ground unless
otherwise specified. All values shown as max or min are classified on absolute value basis.
Note 3: All typical values are V
CC
= 5V, T
A
= 25C.
Note 4: Only one output at a time should be shorted.
Note 5:
Difference between complementary outputs at the 50% point.
Note 6: Differential Delays are defined as calculated results from single ended rise and fall time measurements. This approach in establishing AC performance
specifications has been taken due to limitations of available Automatic Test Equipment (ATE).
The calculated ATE results assume a linear transition between measurement points and are a result of the following equations:
Where:
Tcp = Crossing Point
Tra, Trb, Tfa and Tfb are time measurements with respect to the input.
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4
Switching Time Waveforms
AC Test Circuits and Switching Waveforms
DS008511-3
DS008511-4
FIGURE 1.
DS008511-5
FIGURE 2.
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