LTC1320
AppleTalk
©
Transceiver
U
Output Waveforms
5V/DIV
2V/DIV
1k
11 22Ω
22Ω
100pF
22Ω
LTC1320 • TA01
FEATURES
s
s
s
s
DESCRIPTIO
s
s
s
s
Single Chip Provides Complete
LocalTalk
©
/AppleTalk
©
Port
Low Power: I
CC
= 1.2mA Typ
Shutdown Pin Reduces I
CC
to 30µA Typ
Drivers Maintain High Impedance in Three-State
or with Power Off
30ns Driver Propagation Delay Typ
5ns Driver Skew Typ
Thermal Shutdown Protection
Drivers are Short-Circuit Protected
The LTC1320 is an RS422/RS562 line transceiver de-
signed to operate on LocalTalk networks. It provides one
differential RS422 driver, one single-ended RS562 driver,
two single-ended RS562 receivers, and one differential
RS422 receiver. The LTC1320 draws only 1.2mA quies-
cent current when active and 30µA in shutdown, making
it ideal for use in battery-powered devices and other
systems where power consumption is a primary concern.
The LTC1320 drivers are specified to drive
±2V
into 100Ω.
Additionally, the driver outputs three-state when disabled,
during shutdown, or when the power is off; they maintain
high impedance even with output common-mode volt-
ages beyond the power supply rails. Both the driver
outputs and receiver inputs are protected against ESD
damage to beyond 5kV.
The LTC1320 is available in the 18-pin SOL package.
APPLICATI
s
s
s
LocalTalk Peripherals
Notebook/Palmtop Computers
Battery-Powered Systems
AppleTalk and LocalTalk are registered trademarks of Apple Computer, Inc.
TYPICAL APPLICATI
Typical LocalTalk Connection
5V
18
1
3
5
RX ENABLE
DATA OUT
SHUTDOWN
8
4
9
14
–5V
LTC1320
#1
16 22Ω
17 22Ω
22Ω
100pF
22Ω
100pF
1k
SIGNALS
ON LINE
LocalTalk
TRANSFORMER
DATA IN
120Ω
DATA IN
TX ENABLE
10 22Ω
UO
UO
S
2V/DIV
100pF
DATA OUT
(REMOTE
RECEIVER)
50ns/DIV
5V/DIV
1
LTC1320
ABSOLUTE
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
TXD
TXI
TXDEN
SD
RXEN
RXO
RXO
RXDO
GND
1
2
3
4
5
6
7
8
9
18 V
DD
17 TXD
–
16 TXD
+
15 TXO
14 V
SS
13 RXI
12 RXI
11 RXD
–
10 RXD
+
Supply Voltage (V
DD
) ................................................ 7V
Supply Voltage (V
SS
) .............................................. – 7V
Input Voltage (Logic Inputs) ......... – 0.3V to V
DD
+ 0.3V
Input Voltage (Receiver Inputs) ............................
±15V
Driver Output Voltage (Forced) .............................
±15V
Output Short-Circuit Duration ......................... Indefinite
Operating Temperature Range ................... 0°C ot 70°C
Storage Temperature Range ................ – 65°c to 150°C
Lead Temperature (Soldering, 10 sec)................ 300°C
ORDER PART
NUMBER
LTC1320CS
S PACKAGE
18-LEAD PLASTIC SOL
LTC1320 • PO01
T
JMAX
= 150°C,
θ
JA
= 100°C/W
Consult factory for Industrial and Military grade parts.
DC ELECTRICAL CHARACTERISTICS
SYMBOL
V
OD
PARAMETER
Differential Driver Output Voltage
Change in Magnitude of Driver
Differential Output Voltage
V
OC
Driver Common-Mode Output Voltage
Output Common-Mode Range
Single-Ended Driver Output Voltage
Input High Voltage
Input Low Voltage
Input Current
Three-State Output Current
Driver Short-Circuit Current
Receiver Input Resistance
V
OH
V
OL
Receiver Output High Voltage
Receiver Output Low Voltage
Receiver Output Short-Circuit Current
Receiver Output Three-State Current
Differential Receiver Threshold Voltage
Differential Receiver Input Hysteresis
Single-Ended Receiver Input Low Voltage
Single-Ended Receiver Input High Voltage
I
DD
I
SS
Supply Current
Supply Current
V
S
=
±5V ±5%,
T
A
= 0°C to 70°C (Notes 2, 3)
MIN
q
q
CONDITIONS
No Load
R
L
= 100Ω (Figure 1)
R
L
= 100Ω (Figure 1)
R
L
= 100Ω (Figure 1)
SD = 5V or Power Off
No Load
R
L
= 400Ω
All Logic Input Pins
All Logic Input Pins
All Logic Input Pins
SD = 5V or Power Off, – 10V < V
O
< 10V
– 5V < V
O
< 5V
– 7V < V
IN
< 7V
I
O
= – 4mA
I
O
= 4mA
0V < V
O
< 5V
0V < V
O
< 5V
– 7V < V
CM
< 7V
– 7V < V
CM
< 7V
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
TYP
MAX
UNITS
V
V
8.0
2.0
0.2
3
±10
±4.0
±3.4
2.0
0.8
±1
±2
35
12
3.5
0.4
7
±2
– 200
70
0.8
2
1.2
30
2
3.0
350
350
85
±100
200
350
±20
±100
500
No Load, SD = 0V
No Load, SD = 5V
No Load, SD = 5V
q
q
q
2
U
V
V
V
V
V
V
V
µA
µA
mA
kΩ
V
V
mA
µA
mV
mV
V
V
mA
µA
µA
W
U
U
W W
W
LTC1320
SWITCHI G CHARACTERISTICS
SYMBOL
t
PLH, HL
t
SKEW
t
r, f
t
ENH, L
t
H, Ldis
t
PLH, HL
t
r, f
t
PLH, HL
t
ENH, L
t
H, Ldis
PARAMETER
Differential Driver Propagation Delay
Differential Driver Output to Output
Differential Driver Rise/Fall Time
Driver Enable to Output Active
Driver Output Active to Disable
Single-Ended Driver Propagation Delay
Single-Ended Driver Rise/Fall Time
Receiver Propagation Delay
Receiver Enable to Output Active
Receiver Output Active to Disable
The
q
denotes specifications which apply over the full operating
temperature range.
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
TYPICAL PERFOR A CE CHARACTERISTICS
Output Swing vs Load Current
5
OUTPUT HIGH
10
3
DIFFERENTIAL OUTPUT SWING (V)
4
SUPPLY CURRENT (mA)
OUTPUT SWING (V)
2
1
0
–1
–2
–3
–4
–5
0
20
60
80
40
OUTPUT CURRENT (mA)
100
OUTPUT LOW
PI FU CTIO S
TXD (Pin 1):
RS422 Differential Driver Input (TTL Compat-
ible).
TXI (Pin 2):
RS562 Single-Ended Driver Input (TTL com-
patible.
TXDEN (Pin 3):
RS422 Differential Driver Output Enable
(TTL Compatible). A high level on this pin forces the
RS422 driver into three-state; a low level enables the
driver. This input does not affect the RS562 single-ended
driver.
SD (Pin 4):
Shutdown Input (TTL Compatible). When this
pin is high, the chip is shut down: all driver outputs three-
state and the supply current drops to 30µA. A low on this
pin allows normal operation.
U W
U
U
V
S
=
±5V ±5%,
T
A
= 0°C to 70°C (Notes 2, 3)
MIN
q
q
q
q
q
q
q
q
q
q
CONDITIONS
R
L
= 100Ω, C
L
= 100pF (Figures 2, 8)
R
L
= 100Ω, C
L
= 100pF (Figures 2, 8)
R
L
= 100Ω, C
L
= 100pF (Figures 2, 8)
C
L
= 100pF (Figures 3, 4, 10)
C
L
= 15pF (Figures 3, 4, 10)
R
L
= 450Ω, C
L
= 100pF (Figures 5, 11)
R
L
= 450Ω, C
L
= 100pF (Figures 5, 12)
C
L
= 15pF (Figures 13, 14)
C
L
= 100pF (Figures 6, 7, 15)
C
L
= 15pF (Figures 6, 7, 15)
TYP
40
10
15
50
50
40
15
60
30
30
MAX
120
50
80
150
150
120
80
160
100
100
UNITS
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
Note 2:
All currents into device pins are positive; all currents out of
device pins are negative. All voltages are referenced to ground unless
otherwise specified.
Note 3:
All typicals are given at V
S
=
±5V,
T
A
= 25°C.
Differential Output Swing vs
Load Current
1.2
Supply Current vs Temperature
8
1.1
I
DD
6
1.0
4
0.004
0.002
I
SS
0
10
50
20
30
40
TEMPERATURE (°C)
60
70
2
0
0
20
60
80
40
OUTPUT CURRENT (mA)
100
0
LTC1320 • G01
LTC1320 • G02
LTC1320 • G03
U
U
3
LTC1320
PI FU CTIO S
RXEN (Pin 5):
Receiver Enable (TTL Compatible). A high
level on this pin disables the receivers and three-states the
logic outputs; a low level allows normal operation. To
prevent erratic behavior at the receiver outputs during
shutdown, RXEN should be pulled high along with SD.
RXO (Pin 6):
Inverting RS562 Single-Ended Receiver
Output.
RXO (Pin 7):
Noninverting RS562 Single-Ended Receiver
Output.
RXDO (Pin 8):
RS422 Differential Receiver Output.
GND (Pin 9):
Ground Pin.
RXD
+
(Pin 10):
RS422 Differential Receiver Noninverting
Input. When this pin is
≥
200mV above RXD
–
, RXDO will
be high; when this pin is
≥
200mV below RXD
–
, RXDO will
be low.
RXD
–
(Pin 11):
RS422 Differential Receiver Inverting
Input.
RXI (Pin 12):
Noninverting RS562 Receiver Input. This
input controls the RXO output; it has no effect on the RXO
output.
RXI (Pin 13):
Inverting RS562 Receiver Input. This input
controls the RXO output; it has no effect on the RXO
output.
V
SS
(Pin 14):
Negative Supply. – 4.75
≥
V
SS
≥
– 5.25V. The
voltage on this pin must never exceed ground on power up
or power-down.
TXO (Pin 15):
RS562 Single-Ended Driver Output.
TXD
+
(Pin 16):
RS422 Differential Driver Noninverting
Output.
TXD
–
(Pin 17):
RS422 Differential Driver Inverting Output.
V
DD
(Pin 18):
Positive Supply. 4.75V
≤
V
DD
≤
5.25V.
TEST CIRCUITS
TXD
+
R
L
/2
V
OD
R
L
/2
TXD
LTC1320 • F01
Figure 1
OUTPUT
UNDER TEST
C
L
500Ω
V
SS
LTC1320 • F04
Figure 4
4
U
U
U
TXD
+
+
V
OC
TXD
R
L
C
L1
C
L2
TXD
–
LTC1320 • TCF02
500Ω
OUTPUT
UNDER TEST
C
L
V
SS
LTC1320 • F03
V
DD
–
Figure 2
Figure 3
TXI
R
L
TXO
500Ω
OUTPUT
UNDER TEST
C
L
LTC1320 • F05
LTC1320 • F06
OUTPUT
UNDER TEST
V
DD
C
L
C
L
500Ω
LTC1320 • F07
Figure 5
Figure 6
Figure 7
LTC1320
SWITCHI G WAVEFOR S
3V
TXD
0V
1.5V
f = 1MHz: t
r
< 10ns: t
f
< 10ns
t
PLH
TXD
–
TXD
+
V
O
1/2 V
O
t
SKEW
t
SKEW
1/2 V
O
LTC1320 • F08
Figure 8
V
OH
V
OL
V
O
–V
O
10%
t
r
90%
V
DIFF
= V(TXD
+
) – V(TXD
–
)
t
f
90%
10%
LTC1320 • F09
Figure 9
3V
RXI
0V
1.5V
f = 1MHz: t
r
< 10ns: t
f
< 10ns
t
PHL
V
OH
RXO
V
OL
1.5V
1.5V
t
PLH
1.5V
3V
TXDEN
0V
5V
TXD
+
, TXD
–
V
OL
V
OH
TXD
+
, TXD
–
–5V
1.5V
f = 1MHz: t
r
≤
10ns: t
f
≤
10ns
t
ENL
0V
OUTPUT NORMALLY LOW
OUTPUT NORMALLY HIGH
0V
t
ENH
Figure 10
2.5V
(RXD
–
) – (RXD
+
)
–2.5V
V
OH
RXDO
V
OL
3V
RXEN
0V
5V
RXO, RXO, RXDO
V
OL
V
OH
RXO, RXO, RXDO
0V
W
U
1.5V
t
PHL
3V
TXI
0V
V
OH
TXO
V
OL
1.5V
f = 1MHz: t
r
< 10ns: t
f
< 10ns
1.5V
t
PLH
0V
LTC1320 • F11
t
PHL
0V
Figure 11
90%
10%
t
r
90%
10%
t
f
LTC1320 • F12
Figure 12
1.5V
t
Ldis
0.5V
3V
RXI
0V
V
OH
RXO
V
OL
1.5V
f = 1MHz: t
r
< 10ns: t
f
< 10ns
1.5V
t
PHL
1.5V
LTC1320 • F13
0.5V
t
Hdis
t
PLH
1.5V
LTC1320 • F10
Figure 13
0V
f = 1MHz: t
r
< 10ns: t
f
< 10ns
t
PHL
1.5V
0V
t
PLH
1.5V
LTC1320 • F14
Figure 14
f = 1MHz: t
r
≤
10ns: t
f
≤
10ns
1.5V
1.5V
t
Ldis
0.5V
t
ENL
1.5V OUTPUT NORMALLY LOW
OUTPUT NORMALLY HIGH
1.5V
t
ENH
t
Hdis
0.5V
LTC1320 • F15
Figure 15
5
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