LTC1385
3.3V Low Power
EIA/TIA-562 Transceiver
FEATURES
s
s
s
s
s
s
s
s
DESCRIPTIO
s
s
Operates from a Single 3.3V Supply
Low Supply Current: I
CC
= 200µA
I
CC
= 35µA in Driver Disable Mode
I
CC
= 0.2µA in Shutdown Mode
ESD Protection Over
±10kV
Uses Small Capacitors: 0.1µF
Operates to 120kBaud
Output Overvoltage Does Not Force Current
Back into Supplies
EIA/TIA-562 I/O Lines Can Be Forced to
±25V
Without Damage
Pin Compatible with LT1180A
The LTC
®
1385 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 0.1µF capacitors.
The transceiver operates in one of three modes: Normal,
Driver Disable or Shutdown. In the Normal mode, I
CC
is
only 200µA 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 35µA. In the Shutdown mode, everything
is turned off and I
CC
drops to 0.2µA.
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, 3kΩ load.
Both driver outputs and receiver inputs can be forced to
±25V
without damage, and can survive multiple
±10kV
ESD strikes.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
s
s
Notebook Computers
Palmtop Computers
TYPICAL APPLICATIO
2-Drivers/2-Receivers with Shutdown
and Driver Disable
2
0.1µF
0.1µF
LOGIC INPUT
4
5
6 V
CC
12
V
CC
LOGIC INPUT
LOGIC OUTPUT
LOGIC OUTPUT
11
13
10
5k
5k
ON/OFF
18
1
DRIVER DISABLE
LTC1385 • TA01
Quiescent and Shutdown Supply Current
vs Temperature
600
1.2
1.0
SHUTDOWN CURRENT (µA)
17
LTC1385
3
7
300k
15
300k
8
14
9
VCC = 3.3V
500
QUIESCENT CURRENT (µA)
0.1µF
562 OUTPUT
0.1µF
400
300
200
100
0
–20
SHUTDOWN
CURRENT
0
20
40
TEMPERATURE (°C)
60
QUIESCENT
CURRENT
562 OUTPUT
562 INPUT
562 INPUT
16
TEST CONDITION: V
CC
= 3.3V
LTC1385 • TA02
U
0.8
0.6
0.4
0.2
0
80
sn1385 1385fas
U
U
1
LTC1385
ABSOLUTE
AXI U
RATI GS
Short-Circuit Duration
V
+
................................................................... 30 sec
V
–
................................................................... 30 sec
Driver Output .............................................. Indefinite
Receiver Output .......................................... Indefinite
Operating Temperature Range
LTC1385C ............................................. 0°C to 70°C
LTC1385I ........................................... – 40°C to 85°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
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
PACKAGE/ORDER I FOR ATIO
TOP VIEW
DRIVER
DISABLE
C1
+
V
+
C1
–
C2
+
C2
–
V
–
TR2 OUT
RX2 IN
1
2
3
4
5
6
7
8
9
20 ON/OFF
19 VCC
18 GND
17 TR1 OUT
16 RX1 IN
15 RX1 OUT
14 TR1 IN
13 TR2 IN
12 RX2 OUT
11 NC
G PACKAGE
20-LEAD SSOP
ORDER PART
NUMBER
LTC1385CG
LTC1385IG
NC 10
T
JMAX
= 125°C,
θ
JA
= 135°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
DC ELECTRICAL CHARACTERISTICS
PARAMETER
Any Driver
Output Voltage Swing
Logic Input Voltage Level
Logic Input Current
Output Short-Circuit Current
Output Leakage Current
CONDITIONS
3k to GND
The
q
denotes specifications which apply over the full operating
temperature range. V
CC
= 3.3V, C1 = C2 = C3 = C4 = 0.1µF, V
ON/OFF
= V
CC
, Driver Disable = V
CC
, unless noted.
MIN
Positive
Negative
q
q
q
q
q
q
q
Input Low Level (V
OUT
= High)
Input High Level (V
OUT
= Low)
V
IN
= V
CC
V
IN
= 0V
V
OUT
= 0V
Shutdown or Driver Disable or V
CC
= 0V (Note 3,4),
V
OUT
=
±20V
2
U
U
W
W W
U
W
TOP VIEW
DRIVER
DISABLE 1
C1
+
2
V
+
C2
+
3
18 ON/OFF
17 V
CC
16 GND
15 TR1 OUT
14 RX1 IN
13 RX1 OUT
12 TR1 IN
11 TR2 IN
10 RX2 OUT
SW PACKAGE
18-LEAD PLASTIC SO
ORDER PART
NUMBER
LTC1385CN
LTC1385CSW
LTC1385IN
LTC1385ISW
C1– 4
5
C2– 6
V– 7
TR2 OUT 8
RX2 IN 9
N PACKAGE
18-LEAD PDIP
T
JMAX
= 125°C,
θ
JA
= 85°C/W
TYP
4.5
– 4.5
1.4
1.4
– 20
±10
±10
MAX
UNITS
V
V
V
V
µA
µA
mA
µA
3.7
– 3.7
2.0
0.8
5
– 40
±500
sn1385 1385fas
LTC1385
DC ELECTRICAL CHARACTERISTICS
PARAMETER
Any Receiver
Input Voltage Thresholds
Hysteresis
Input Resistance
Output Voltage
Output Short-Circuit Current
Output Leakage Current
Power Supply Generator
V
+
Output Voltage
V
–
Output Voltage
Supply Rise Time
Power Supply
V
CC
Supply Current
Supply Leakage Current (V
CC
)
Digital Input Threshold Low
Digital Input Threshold High
CONDITIONS
Input Low Threshold
Input High Threshold
The
q
denotes specifications which apply over the full operating
temperature range. V
CC
= 3.3V, C1 = C2 = C3 = C4 = 0.1µF, V
ON/OFF
= V
CC
, Driver Disable = V
CC
, unless noted.
MIN
q
q
q
TYP
1.3
1.7
0.4
5
0.2
3.2
– 20
7
1
5.7
5.5
– 5.3
– 5.0
0.2
MAX
UNITS
V
V
V
kΩ
V
V
mA
mA
µA
V
V
V
V
ms
0.8
0.1
3
3.0
–5
2
– 10V
≤
V
IN
≤
10V
Output Low, I
OUT
= – 1.6mA (V
CC
= 3.3V)
Output High, I
OUT
= 160µA (V
CC
= 3.3V)
Sinking Current, V
OUT
= V
CC
Sourcing Current, V
OUT
= 0V
Shutdown (Note 4), 0V
≤
V
OUT
≤
V
CC
I
OUT
= 0mA
I
OUT
= 5mA
I
OUT
= 0mA
I
OUT
= – 5mA
Shutdown or Driver Disable to Turn-On
No Load (Note 2), 0°C to 70°C
No Load (Note 2), – 40°C to 85°C
Shutdown (Note 4)
Driver Disable (Note 3)
q
q
2.4
1.0
7
0.4
q
10
q
q
q
q
q
q
2.0
0.2
3.5
0.2
35
1.4
1.4
0.5
1.0
10
50
0.8
mA
mA
µA
µA
V
V
AC CHARACTERISTICS
PARAMETER
Slew Rate
Driver Propagation Delay
(TTL to EIA / TIA-562)
Receiver Propagation Delay
(EIA / TIA-562 to TTL)
The
q
denotes specifications which apply over the full operating temperature range.
V
CC
= 3.3V, C1 = C2 = C3 = C4 = 0.1µF, unless noted.
CONDITIONS
R
L
= 3k, C
L
= 51pF
R
L
= 3k, C
L
= 1000pF
t
HLD
(Figure 1)
t
LHD
(Figure 1)
t
HLR
(Figure 2)
t
LHR
(Figure 2)
MIN
3
q
q
q
q
TYP
8
5
2
2
0.3
0.2
MAX
30
3.5
3.5
0.8
0.8
UNITS
V/µs
V/µs
µs
µs
µs
µs
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.
sn1385 1385fas
3
LTC1385
TYPICAL PERFOR A CE CHARACTERISTICS
Driver Output Voltage
vs Temperature
5
4
DRIVER OUTPUT VOLTAGE (V)
THRESHOLD VOLTAGE (V)
3
2
1
0
–1
–2
–3
–4
–5
0
10
OUTPUT HIGH
V
CC
= 3.3V
1.8
1.6
1.4
V
TH+
ALL DRIVERS WITH LOAD
R
L
= 3k
SUPPLY CURRENT (mA)
OUTPUT LOW
V
CC
= 3.3V
40
30
20
50
TEMPERATURE (°C)
V
CC
Supply Current
vs Temperature
4.5
4.0
LEAKAGE CURRENT (µA)
SUPPLY CURRENT (mA)
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
0
10
2 DRIVERS LOADED
R
L
= 3k
SHORT-CIRCUIT CURRENT (mA)
1 DRIVER LOADED
R
L
= 3k
20
30
50
40
TEMPERATURE (°C)
LTC1385 • TPC04
Receiver Short-Circuit Current
vs Temperature
45
40
SHORT-CIRCUIT CURRENT (mA)
DRIVER
OUTPUT
R
L
= 3k
C
L
= 1000pF
DRIVER
OUTPUT
R
L
= 3k
35
30
25
20
15
10
5
0
0
10
30
50
40
20
TEMPERATURE (°C)
60
70
I
SC+
I
SC–
LTC1385 • TPC06
4
U W
60
70
LTC1385 • TPC01
Receiver Input Thresholds
vs Temperature
2.2
2.0
15
20
Supply Current vs Data Rate
V
CC
= 3.3V
R
L
= 3k
C
L
= 2500pF
ALL DRIVERS ACTIVE
10
V
TH–
1.2
1.0
0
10
40
30
50
20
TEMPERATURE (˚C)
60
70
5
0
0
20
40
80 100
60
DATA RATE (kBAUD)
120
140
LTC1385 • TPC02
LTC1385 • TPC03
Driver Leakage in Shutdown
vs Temperature
45
40
35
30
25
20
15
10
5
0
60
70
18
16
14
12
10
8
6
4
2
0
Driver Short-Circuit Current
vs Temperature
I
SC–
V
OUT
= –20V
I
SC+
V
OUT
= 20V
0
10
30
20
40
50
TEMPERATURE (°C)
60
70
0
10
30
50
40
20
TEMPERATURE (°C)
60
70
LTC1385 • TPC05
LTC1385 • TPC06
Driver Output Waveforms
Receiver Output Waveform
RECEIVER
OUTPUT
C
L
= 51pF
INPUT
INPUT
LTC1385 • TPC08
LTC1385 • TPC09
sn1385 1385fas
LTC1385
PI FU CTIO S
V
CC
:
3.3V Input Supply Pin. This pin should be decoupled
with a 0.1µF 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
0.2µA 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 35µA. 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 = 0.1µF 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 = 0.1µF for charge storage.
C1
+
, C1
–
, C2
+
, C2
–
:
Commutating Capacitor Inputs. These
pins require two external capacitors C = 0.1µF: 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 2Ω.
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
DRIVER
INPUT
DRIVER
OUTPUT
t
LHD
V
CC
1.4V
1.4V
0V
V
+
0V
t
HLD
1385 F01
Figure 1. Driver Propagation Delay Timing
W
W
U
U
U
U
RX
INPUT
RX
OUTPUT
t
LHR
1.7V
V
CC
1.3V
0V
2.4V
0.8V
t
HLR
V
CC
0V
1385 F02
0V
V
–
Figure 2. Receiver Propagation Delay Timing
sn1385 1385fas
5
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