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1
LTC1385
3.3V Low Power
EIA/TIA-562 Transceiver
S
FEATURE
D
U
ESCRIPTIO
s
Operates from a Single 3.3V Supply
s
Low Supply Current: I
CC
= 200
A
s
I
CC
= 35
A in Driver Disable Mode
s
I
CC
= 0.2
A in Shutdown Mode
s
ESD Protection Over
10kV
s
Uses Small Capacitors: 0.1
F
s
Operates to 120kBaud
s
Output Overvoltage Does Not Force Current
Back into Supplies
s
EIA/TIA-562 I/O Lines Can Be Forced to
25V
Without Damage
s
Pin Compatible with LT1180A
The LTC1385 is an ultra-low power, 2-driver/2-receiver
EIA / TIA-562 transceiver which operates from a single
3.3V supply. The charge pump requires only four space-
saving 0.1
F capacitors.
The transceiver operates in one of three modes: Normal,
Driver Disable or Shutdown. In the Normal mode, I
CC
is
only 200
A in the unloaded condition. In the Driver Disable
mode, the charge pump is turned off, the driver outputs
are forced into three-state, both receivers are kept active,
and I
CC
drops to 35
A. In the Shutdown mode, everything
is turned off and I
CC
drops to 0.2
A.
The LTC1385 is fully compliant with all data rate and
overvoltage EIA / TIA-562 specifications. The transceiver
can operate up to 120kbaud with a 1000pF, 3k
load.
Both driver outputs and receiver inputs can be forced to
25V without damage, and can survive multiple
10kV
ESD strikes.
U
S
A
O
PPLICATI
s
Notebook Computers
s
Palmtop Computers
U
A
O
PPLICATI
TYPICAL
Quiescent and Shutdown Supply Current
vs Temperature
2-Drivers/2-Receivers with Shutdown
and Driver Disable
TEMPERATURE (C)
QUIESCENT CURRENT (
A)
600
500
400
300
200
100
0
20
40
60
LTC1385 TA02
80
0
1.2
1.0
0.8
0.6
0.4
0.2
0
SHUTDOWN CURRENT (
A)
QUIESCENT
CURRENT
SHUTDOWN
CURRENT
TEST CONDITION: V
CC
= 3.3V
20
LTC1385 TA01
0.1
F
0.1
F
0.1
F
0.1
F
LTC1385
DRIVER DISABLE
2
4
5
6
12
11
13
10
18
14
9
16
1
LOGIC INPUT
LOGIC INPUT
LOGIC OUTPUT
LOGIC OUTPUT
ON/OFF
17
3
7
15
562 OUTPUT
VCC = 3.3V
562 OUTPUT
562 INPUT
562 INPUT
5k
5k
300k
V
CC
300k
V
CC
8
2
LTC1385
A
U
G
W
A
W
U
W
A
R
BSOLUTE
XI
TI
S
Supply Voltage (V
CC
) ................................................ 5V
Input Voltage
Driver ....................................... 0.3V to V
CC
+ 0.3V
Receiver ............................................... 25V to 25V
Digital Input ............................... 0.3V to V
CC
+ 0.3V
Output Voltage
Driver .................................................... 25V to 25V
Receiver .................................... 0.3V to V
CC
+ 0.3V
Short-Circuit Duration
V
+
................................................................... 30 sec
V
................................................................... 30 sec
Driver Output .............................................. Indefinite
Receiver Output .......................................... Indefinite
Operating Temperature Range .................... 0
C to 70
C
Storage Temperature Range ................ 65
C to 150
C
Lead Temperature (Soldering, 10 sec)................. 300
C
W
U
U
PACKAGE/ORDER I FOR ATIO
ELECTRICAL C
C
HARA TERISTICS
C
D
LTC1385CG
ORDER PART
NUMBER
ORDER PART
NUMBER
LTC1385CN
LTC1385CS
Consult factory for Industrial and Military grade parts.
T
JMAX
= 125
C,
JA
= 135
C/W
1
2
3
4
5
6
7
8
9
10
TOP VIEW
G PACKAGE
20-LEAD SSOP
20
19
18
17
16
15
14
13
12
11
C1
+
V
+
C1
C2
+
C2
V
TR2 OUT
RX2 IN
NC
ON/OFF
VCC
GND
TR1 OUT
RX1 IN
RX1 OUT
TR1 IN
TR2 IN
RX2 OUT
NC
DRIVER
DISABLE
T
JMAX
= 125
C,
JA
= 85
C/W
TOP VIEW
N PACKAGE
18-LEAD PLASTIC DIP
S PACKAGE
18-LEAD PLASTIC SOL
1
2
3
4
5
6
7
8
9
18
17
16
15
14
13
12
11
10
DRIVER
DISABLE
C1
+
V
+
C1
C2
+
C2
V
TR2 OUT
RX2 IN
ON/OFF
V
CC
GND
TR1 OUT
RX1 IN
RX1 OUT
TR1 IN
TR2 IN
RX2 OUT
V
CC
= 3.3V, C1 = C2 = C3 = C4 = 0.1
F, V
ON/OFF
= V
CC
, Driver Disable = V
CC
, unless otherwise noted.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Any Driver
Output Voltage Swing
3k to GND
Positive
q
3.7
4.5
V
Negative
q
3.7
4.5
V
Logic Input Voltage Level
Input Low Level (V
OUT
= High)
q
1.4
0.8
V
Input High Level (V
OUT
= Low)
q
2.0
1.4
V
Logic Input Current
V
IN
= V
CC
q
5
A
V
IN
= 0V
q
20
40
A
Output Short-Circuit Current
V
OUT
= 0V
10
mA
Output Leakage Current
Shutdown or Driver Disable or V
CC
= 0V (Note 3,4),
q
10
500
A
V
OUT
=
20V
3
LTC1385
ELECTRICAL C
C
HARA TERISTICS
C
D
V
CC
= 3.3V, C1 = C2 = C3 = C4 = 0.1
F, V
ON/OFF
= V
CC
, Driver Disable = V
CC
, unless otherwise noted.
C
C
HARA TERISTICS
AC
V
CC
= 3.3V, C1 = C2 = C3 = C4 = 0.1
F, unless otherwise noted.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Slew Rate
R
L
= 3k, C
L
= 51pF
8
30
V/
s
R
L
= 3k, C
L
= 1000pF
3
5
V/
s
Driver Propagation Delay
t
HLD
(Figure 1)
q
2
3.5
s
(TTL to EIA / TIA-562)
t
LHD
(Figure 1)
q
2
3.5
s
Receiver Propagation Delay
t
HLR
(Figure 2)
q
0.3
0.8
s
(EIA / TIA-562 to TTL)
t
LHR
(Figure 2)
q
0.2
0.8
s
The
q
denotes specifications which apply over the operating temperature
range 0
C
T
A
70
C.
Note 1: Absolute maximum ratings are those values beyond which the life
of the device may be impaired.
Note 2: Supply current is measured with driver and receiver outputs
unloaded.
Note 3: Measurements made in the Driver Disable mode are performed
with V
DRIVER DISABLE
= GND and V
ON/OFF
= V
CC
.
Note 4: Measurements made in the Shutdown mode are performed with
V
ON/OFF
= 0V.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Any Receiver
Input Voltage Thresholds
Input Low Threshold
q
0.8
1.3
V
Input High Threshold
q
1.7
2.4
V
Hysteresis
q
0.1
0.4
1.0
V
Input Resistance
10V
V
IN
10V
3
5
7
k
Output Voltage
Output Low, I
OUT
= 1.6mA (V
CC
= 3.3V)
q
0.2
0.4
V
Output High, I
OUT
= 160
A (V
CC
= 3.3V)
q
3.0
3.2
V
Output Short-Circuit Current
Sinking Current, V
OUT
= V
CC
5
20
mA
Sourcing Current, V
OUT
= 0V
2
7
mA
Output Leakage Current
Shutdown (Note 4), 0V
V
OUT
V
CC
q
1
10
A
Power Supply Generator
V
+
Output Voltage
I
OUT
= 0mA
5.7
V
I
OUT
= 5mA
5.5
V
V
Output Voltage
I
OUT
= 0mA
5.3
V
I
OUT
= 5mA
5.0
V
Supply Rise Time
Shutdown or Driver Disable to Turn-On
0.2
ms
Power Supply
V
CC
Supply Current
No Load (Note 2)
q
0.2
0.5
mA
Supply Leakage Current (V
CC
)
Shutdown (Note 4)
q
0.2
10
A
Driver Disable (Note 3)
q
35
50
A
Digital Input Threshold Low
q
1.4
0.8
V
Digital Input Threshold High
q
2.0
1.4
V
4
LTC1385
TYPICAL PERFOR
M
A
N
CE CHARACTERISTICS
U
W
DATA RATE (kBAUD)
0
SUPPLY CURRENT (mA)
60
LTC1385 TPC03
10
5
20
40
80
0
20
15
100
120
140
V
CC
= 3.3V
R
L
= 3k
C
L
= 2500pF
ALL DRIVERS ACTIVE
Supply Current vs Data Rate
TEMPERATURE (C)
0
0
SUPPLY CURRENT (mA)
0.5
1.5
2.0
2.5
40
4.5
LTC1385 TPC04
1.0
20
10
50
60
30
70
3.0
3.5
4.0
2 DRIVERS LOADED
R
L
= 3k
1 DRIVER LOADED
R
L
= 3k
V
CC
Supply Current
vs Temperature
TEMPERATURE (C)
0
5
DRIVER OUTPUT VOLTAGE (V)
4
2
1
0
5
2
20
40
50
LTC1385 TPC01
3
3
4
1
10
30
60
70
OUTPUT HIGH
V
CC
= 3.3V
OUTPUT LOW
V
CC
= 3.3V
ALL DRIVERS WITH LOAD
R
L
= 3k
Driver Output Voltage
vs Temperature
TEMPERATURE (C)
0
THRESHOLD VOLTAGE (V)
1.8
2.0
2.2
30
V
TH
+
V
TH
50
LTC1385 TPC02
1.6
1.4
10
20
40
60
70
1.2
1.0
Receiver Input Thresholds
vs Temperature
Driver Leakage in Shutdown
vs Temperature
TEMPERATURE (C)
0
LEAKAGE CURRENT (
A)
60
45
40
35
30
25
20
15
10
5
0
LTC1385 TPC05
20
70
10
30
40
50
V
OUT
= 20V
V
OUT
= 20V
Driver Short-Circuit Current
vs Temperature
TEMPERATURE (C)
0
0
SHORT-CIRCUIT CURRENT (mA)
2
6
8
10
20
18
LTC1385 TPC06
4
10
30
I
SC
I
SC
+
40
60
50
70
12
14
16
Receiver Short-Circuit Current
vs Temperature
TEMPERATURE (C)
0
0
SHORT-CIRCUIT CURRENT (mA)
5
15
20
25
20
45
LTC1385 TPC06
10
10
30
I
SC
40
60
50
70
30
35
40
I
SC
+
Driver Output Waveforms
Receiver Output Waveform
DRIVER
OUTPUT
R
L
= 3k
C
L
= 1000pF
INPUT
DRIVER
OUTPUT
R
L
= 3k
LTC1385 TPC08
LTC1385 TPC09
RECEIVER
OUTPUT
C
L
= 51pF
INPUT
5
LTC1385
V
CC
: 3.3V Input Supply Pin. This pin should be decoupled
with a 0.1
F ceramic capacitor.
GND: Ground Pin.
ON/OFF: TTL/CMOS Compatible Shutdown Pin. A logic
low puts the device in the Shutdown mode independent
of the Driver Disable pin. The supply current drops to
0.2
A and all driver and receiver outputs are forced into
three-state.
DRIVER DISABLE: TTL/CMOS Compatible Input Pin. With
the ON/OFF pin held high, a logic low forces the part into
the Driver Disable mode with the charge pump turned off
and the driver outputs forced into three-state. Both receiv-
ers remain active and the supply current drops to 35
A. A
logic high forces the part into the Normal mode.
V
+
: Positive Supply Output (EIA/TIA-562 Drivers).
V
+
2V
CC
1V. This pin requires an external capacitor
C = 0.1
F for charge storage. The capacitor may be tied
to ground or V
CC
. With multiple devices, the V
+
and V
pins may share a common capacitor. For a large number
of devices, increasing the size of the shared common
storage capacitors is recommended to reduce ripple.
V
: Negative Supply Output (EIA/TIA-562 Drivers).
V
(2V
CC
1.3V). This pin requires an external
capacitor C = 0.1
F for charge storage.
PI FU CTIO S
U
U
U
C1
+
, C1
, C2
+
, C2
: Commutating Capacitor Inputs. These
pins require two external capacitors C = 0.1
F: one from
C1
+
to C1
, and another from C2
+
to C2
. To maintain
charge pump efficiency, the capacitor's effective series
resistance should be less than 2
.
TR IN: EIA/TIA-562 Driver Input Pins. Inputs are TTL/
CMOS compatible. The inputs of unused drivers can be left
unconnected since 300k input pull-up resistors to V
CC
are
included on chip. To minimize power consumption, the
internal driver pull-up resistors are disconnected from V
CC
in the Shutdown mode.
TR OUT: Driver Outputs at EIA/TIA-562 Voltage Levels.
Outputs are in a high impedance state when in the Shut-
down or Driver Disable mode or V
CC
= 0V. The driver
outputs are protected against ESD to
10kV for human
body model discharges.
RX IN: Receiver Inputs. These pins can be forced to
25V
without damage. The receiver inputs are protected against
ESD to
10kV for human body model discharges. Each
receiver provides 0.4V of hysteresis for noise immunity.
RX OUT: Receiver Outputs with TTL/CMOS Voltage Lev-
els. Outputs are in a high impedance state when in the
Shutdown mode.
SWITCHI G TI E WAVEFOR S
W
W
U
1.4V
0V
V
CC
0V
V
+
V
0V
DRIVER
INPUT
DRIVER
OUTPUT
1.4V
t
HLD
t
LHD
1385 F01
Figure 1. Driver Propagation Delay Timing
0.8V
V
CC
0V
2.4V
RX
INPUT
RX
OUTPUT
1.3V
t
HLR
1.7V
t
LHR
1385 F02
V
CC
0V
Figure 2. Receiver Propagation Delay Timing
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