Page 1
Advanced Power Management and
FEATURES
■
One Receiver Remains Active While in Shutdown
■
ESD Protection over ±15kV
■
Uses Small Capacitors: 0.1µF, 0.2µF, 1.0µF
■
60µA Supply Current in Shutdown
■
Pin Compatible with LT1137A
■
120kBaud Operation for RL = 3k, CL = 2500pF
■
250kBaud Operation for RL = 3k, CL = 1000pF
■
Operates to 120kBaud
■
CMOS Comparable Low Power 30mW
■
Operates from a Single 5V Supply
■
Easy PC Layout—Flowthrough Architecture
■
Rugged Bipolar Design
■
Outputs Assume a High Impedance State When Off
or Powered Down
■
Absolutely No Latchup
■
Available in SO and SSOP Packages
U
APPLICATIO S
■
Notebook Computers
■
Palmtop Computers
LT1237
5V RS232 Transceiver with
One Receiver Active in Shutdown
U
DESCRIPTIO
The LT®1237 is an advanced low power three driver, five
receiver RS232 transceiver. Included on the chip is a
shutdown pin for reducing supply current near zero.
During shutdown one receiver remains active to detect
incoming RS232 signals, for example, to wake up a
system.
The LT1237 is fully compliant with all EIA RS232 specifications. New ESD structures on the chip allow the LT1237
to survive multiple ±15kV strikes, eliminating the need for
costly TransZorbs® on the RS232 line pins.
The LT1237 operates in excess of 120kbaud even driving
heavy capacitive loads. Two shutdown modes allow the
driver outputs to be shut down separately from the receivers for more versatile control of the RS232 interface.
During shutdown, drivers and receivers assume a high
impedance state.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TransZorb is a registered trademark of General Instruments, GSI
TYPICAL APPLICATIO
+
1
1.0µF
2 × 0.1µF
TO
LINE
V
5V V
DRIVER 1 OUT
RX1 IN
DRIVER 2 OUT
RX2 IN
RX3 IN
RX4 IN
DRIVER 3 OUT
RX5 IN (LOW-Q)
ON/OFF
CC
10
11
12
13
14
LT1237
2
3
4
5
6
7
8
9
U
–
V
28
27
26
25
DRIVER 1 IN
24
RX1 OUT
23
DRIVER 2 IN
22
RX2 OUT
21
RX3 OUT
20
RX4 OUT
19
DRIVER 3 IN
18
RX5 OUT (LOW-Q)
17
GND
DRIVER
16
DISABLE
15
2 × 0.1µF
0.1µF
TO LOGIC
RING DETECT IN
µCONTROLLER OR
µPROCESSOR
SHUTDOWN
CONTROL OUT
R
LT1237 TA01
RECEIVER
OUTPUT
= 50pF
C
L
DRIVER
OUTPUT
R
= 2500pF
C
L
= 3k
L
INPUT
Output Waveforms
1237 TA02
1
Page 2
LT1237
A
W
O
LUTEXI TIS
S
A
WUW
U
ARB
G
(Note 1)
Supply Voltage (VCC) ................................................ 6V
V+........................................................................ 13.2V
V–...................................................................... –13.2V
Input Voltage
Driver ........................................................... V– to V
Receiver ............................................... – 30V to 30V
Output Voltage
Driver .................................................... – 30V to 30V
Receiver .................................... –0.3V to VCC + 0.3V
Short Circuit Duration
V+................................................................... 30 sec
V–................................................................... 30 sec
Driver Output.............................................. Indefinite
Receiver Output.......................................... Indefinite
Operating Temperature Range
LT1237C................................................. 0°C to 70°C
Storage Temperature Range ................ –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
PACKAGE
5V V
+
DR1 OUT
RX1 IN
DR2 OUT
RX2 IN
RX3 IN
RX4 IN
DR3 OUT
RX5 IN
(LOW-Q)
ON/OFF
28-LEAD PLASTIC SSOP
/
O
TOP VIEW
+
V
1
2
CC
+
C1
3
–
C1
4
5
6
7
8
9
10
11
12
13
14
NC
G PACKAGE
SW PACKAGE
28-LEAD (WIDE) PLASTIC SO
T
= 150°C, θ
JMAX
T
= 150°C, θ
JMAX
T
= 150°C, θ
JMAX
WU
RDER I FOR ATIO
ORDER PART
NUMBER
LT1237CG
LT1237CNW
LT1237CSW
28
27
26
25
24
23
22
21
20
19
18
17
16
15
NW PACKAGE
28-LEAD (WIDE) PDIP
= 96°C/ W (G)
JA
= 56°C/ W (NW)
JA
= 85°C/ W (SW)
JA
–
V
–
C2
+
C2
DR1 IN
RX1 OUT
DR2 IN
RX2 OUT
RX3 OUT
RX4 OUT
DR3 IN
RX5 OUT
(LOW-Q)
GND
DRIVER
DISABLE
NC
U
Consult factory for Industrial and Military grade parts.
LECTRICAL C CHARA TERIST
E
ICS
The ● denotes specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. (Note 2)
PARAMETER CONDITIONS MIN TYP MAX UNITS
Power Supply Generator
V+ Output 7.9 V
V– Output –7 V
Supply Current (V
Supply Current when OFF (V
Supply Rise Time C1 = C2 = 0.2µF, 2 ms
Shutdown to Turn-On C+ = 1.0µF, C– = 0.1µF
ON/OFF Pin Thresholds Input Low Level (Drivers Enabled) 0.8 1.2 V
ON/OFF Pin Current 0V ≤ V
DRIVER DISABLE Pin Thresholds Input Low Level (Drivers Enabled) ● 0.8 1.4 V
DRIVER DISABLE Pin Current 0V ≤ V
Oscillator Frequency Driver Outputs Loaded RL = 3k 130 kHz
)T
CC
) Shutdown (Note 4) ● 0.06 0.15 mA
CC
= 25°C (Note 3) 6 12 mA
A
Driver Disable 3.00 mA
Input High Level (Drivers Disabled) 1.6 2.4 V
≤ 5V ● –15 80 µA
ON/OFF
Input High Level (Drivers Disabled) ● 1.4 2.4 V
DRIVER DISABLE
● 614 mA
≤ 5V ● –10 500 µA
2
Page 3
LT1237
LECTRICAL C CHARA TERIST
E
temperature range, otherwise specifications are at TA = 25°C. (Note 2)
PARAMETER CONDITIONS MIN TYP MAX UNITS
Any Driver
Output Voltage Swing Load = 3k to GND Positive
Logic Input Voltage Level Input Low Level (V
Input High Level (V
Logic Input Current 0.8V ≤ VIN ≤ 2V ● 520 µA
Output Short-Circuit Current V
Output Leakage Current Shutdown V
Data Rate (Note 7) R
Slew Rate R
Propagation Delay Output Transition t
Any Receiver
Input Voltage Thresholds Input Low Threshold (V
Hysteresis ● 0.1 0.4 1.0 V
Input Resistance VIN = ±10V 3 5 7 kΩ
Output Leakage Current Shutdown (Note 4) 0 ≤ V
Receivers 1, 2, 3, 4
Output Voltage Output Low, I
Output Short-Circuit Current Sinking Current, V
Propagation Delay Output Transition tHL High to Low (Note 6) 250 600 ns
Receiver 5 (LOW I
Output Voltage Output Low, I
Output Short-Circuit Current Sinking Current, V
Propagation Delay Output Transition tHL High to Low (Note 6) 1.0 3 µs
SUPPLY
RX)
= 0V ±917 mA
OUT
= 3k, CL = 2500pF 120 kBaud
L
RL = 3k, CL = 1000pF 250 kBaud
= 3k, CL = 51pF 15 30 V/µs
L
RL = 3k, CL = 2500pF 4 7 V/µs
Output Transition tLH Low to High 0.5 1.3 µs
Input High Threshold (V
Output High, I
Sourcing Current, V
Output Transition tLH Low to High 350 600 ns
Output High, I
Sourcing Current, V
Output Transition tLH Low to High 0.6 3 µs
ICS
= ±30V (Note 4) ● 10 100 µA
OUT
OUT
OUT
OUT
OUT
The ● denotes specifications which apply over the full operating
● 5.0 7.5 V
Negative ● – 6.3 –5.0 V
= High) ● 1.4 0.8 V
OUT
= Low) ● 2.0 1.4 V
OUT
High to Low (Note 5) 0.6 1.3 µs
HL
= High) 0.8 1.3 V
OUT
= Low) 1.7 2.4 V
OUT
≤ V
OUT
CC
= –1.6mA ● 0.2 0.4 V
= 160µA (VCC = 5V) ● 3.5 4.2 V
= V
OUT
CC
= 0V 10 20 mA
OUT
= – 500µA ● 0.2 0.4 V
= 160µA (VCC = 5V) ● 3.5 4.2 V
= V
OUT
CC
= 0V 2 4 mA
OUT
● 110 µA
–10 –20 mA
–2 –4 mA
Note 1: Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired.
Note 2: Testing done at V
specified.
Note 3: Supply current is measured as the average over several charge
pump burst cycles. C
are open, with all driver inputs tied high.
Note 4: Measurements in shutdown are performed with V
Supply current measurements using driver disable are performed with
V
DRIVER DISABLE
≥ 3V.
= 5V and V
CC
+
= 1.0µF, C– = 0.1µF, C1 = C2 = 0.2µF. All outputs
= 3V, unless otherwise
ON/OFF
ON/OFF
≤ 0.1V.
Note 5: For driver delay measurements, R
points are set between the driver’s input logic threshold and the output
transition to the zero crossing (t
Note 6: For receiver delay measurements, CL = 51pF. Trigger points are
set between the receiver’s input logic threshold and the output transition
to standard TTL/CMOS logic threshold (tHL = 1.3V to 2.4V and tLH = 1.7V
to 0.8V).
Note 7: Data rate operation guaranteed by slew rate, short-circuit current
and propagation delay tests.
HL
= 3k and CL = 51pF. Trigger
L
= 1.4V to 0V and tLH = 1.4V to 0V).
3
Page 4
LT1237
LPER
UW
R
F
O
ATYPICA
CCHARA TERIST
E
C
ICS
Driver Output Voltage
10
RL = 3k
8
6
4
2
0
–2
–4
–6
DRIVER OUTPUT VOLTAGE (V)
–8
–10
–55
150
125
100
75
50
SUPPLY CURRENT (µA)
25
–25
0
OUTPUT HIGH
OUTPUT LOW
25
TEMPERATURE (°C)
Receiver Input Thresholds
VCC = 5V
VCC = 4.5V
VCC = 4.5V
VCC = 5V
50
75
100
125
1237 G01
3.00
2.75
2.50
2.25
2.00
1.75
1.50
1.25
THRESHOLD VOLTAGE (V)
1.00
0.75
0.50
–55
0
–25
TEMPERATURE (°C)
INPUT HIGH
INPUT LOW
50
25
100
125
1237 G02
75
Supply Current in Driver Disable
5
4
3
2
SUPPLY CURRENT (mA)
1
Supply Current vs Data Rate
80
3 DRIVERS ACTIVE
= 3k
R
70
L
= 2500pF
C
L
60
50
40
30
SUPPLY CURRENT (mA)
20
10
0
25 50 125 150
0
75
DATA RATE (kBAUD)
DRIVER DISABLE ThresholdSupply Current in Shutdown
3.0
2.5
2.0
1.5
1.0
THRESHOLD VOLTAGE (V)
0.5
100
1237 G03
0
–55
–25 0
TEMPERATURE (°C)
ON/OFF Thresholds
3.0
2.5
2.0
1.5
1.0
THRESHOLD VOLTAGE (V)
0.5
0
–55
–25 0
ON THRESHOLD
OFF THRESHOLD
TEMPERATURE (°C)
50 100 125
25 75
50 100 125
25 75
1237 G04
1237 G07
0
–55
0
–25
TEMPERATURE (°C)
Supply Current
40
35
30
25
20
15
SUPPLY CURRENT (mA)
10
5
0
–55 0
3 DRIVERS LOADED
1 DRIVER LOADED
–25
TEMPERATURE (°C)
25
= 3k
R
L
= 3k
R
L
NO LOAD
25
50
75
100
125
1237 G05
0
–55
–25 0
50 100 125
25 75
TEMPERATURE (°C)
1237 G06
Driver Leakage in Shutdown
100
10
V
= 30V
1
LEAKAGE CURRENT (µA)
50
75
100
125
1237 G08
0.1
–55 0
–25
TEMPERATURE (°C)
OUT
V
= –30V
OUT
50
25
75
100
125
1237 G09
4
Page 5
LPER
30
F
O
R
ATYPICA
UW
CCHARA TERIST
E
C
LT1237
ICS
Receiver Short-Circuit CurrentDriver Short-Circuit Current
50
25
20
15
10
SHORT-CIRCUIT CURRENT (mA)
5
0
–55
–25 0
Receiver Output Waveforms
RX5 OUTPUT
= 50pF
C
L
RX1 TO RX4
OUTPUT
CL = 50pF
INPUT
50 100 125
25 75
TEMPERATURE (°C)
+
I
SC
–
I
SC
1237 G10
40
–55
RX1 TO RX4
RX5 I
RX5 I
–25
I
SC
0
+
–
SC
+
SC
25
TEMPERATURE (°C)
30
20
10
SHORT-CIRCUIT CURRENT (mA)
0
RX1 TO RX4
–
I
SC
50
75
100
125
1237 G11
Driver Output Waveforms
DRIVER OUTPUT
DRIVER OUTPUT
1237 G12
= 2500pF
C
L
= 3k
R
L
= 3k
R
L
INPUT
1237 G13
U
UU
PI FU CTIO S
VCC: 5V Input Supply Pin. This pin should be decoupled
with a 0.1µF ceramic capacitor close to the package pin.
Insufficient supply bypassing can result in low output
drive levels and erratic charge pump operation.
GND: Ground Pin.
ON/OFF: TTL/CMOS Compatible Operating Mode Control.
A logic low puts the device in the low power shutdown
mode. All three drivers and four receivers (RX1, RX2, RX3,
and RX4) assume a high impedance output state in shutdown. Only receiver RX5 remains active while the transceiver is in shutdown. The transceiver consumes only
60µA of supply current while in shutdown. A logic high
fully enables the transceiver.
DRIVER DISABLE: This pin provides an alternate control
for the charge pump and RS232 drivers. A logic high on
this pin shuts down the charge pump and places all driver
outputs in a high impedance state. All five receivers remain
active under these conditions. Floating the driver disable
pin or driving it to a logic low level fully enables the
transceiver. A logic low on the ON/OFF pin supersedes the
state of the DRIVER DISABLE pin. Supply current drops to
3mA when in driver disable mode.
V+: Positive Supply Output (RS232 Drivers). V+ ≈ 2VCC –
1.5V. This pin requires an external charge storage capacitor C ≥ 1.0µF, tied to ground or VCC. Larger value capacitors may be used to reduce supply ripple. The ratio of the
capacitors on V+ and V– should be greater than 5 to 1.
V–: Negative Supply Output (RS232 Drivers). V– ≈
–(2VCC – 2.5V). This pin requires an external charge
storage capacitor C ≥ 0.1µF. See the Applications Infor-
mation section for guidance in choosing filter capacitors
for V+ and V–.
5
Page 6
LT1237
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UU
PI FU CTIO S
C1+, C1–, C2+, C2–: Commutating Capacitor Inputs, require two external capacitors C ≥ 0.2µF: one from C1+ to
C1–, and another from C2+ to C2–. The capacitor’s effective series resistance should be less than 2Ω. For C ≥ 1µF,
low ESR tantalum capacitors work well in this application,
although small value ceramic capacitors may be used with
a minimal reduction in charge pump compliance.
DRIVER IN: RS232 Driver Input Pins. These inputs are
TTL/CMOS compatible. Inputs should not be allowed to
float. Tie unused inputs to VCC.
DRIVER OUT: Driver Outputs at RS232 Voltage Levels.
Driver output swing meets RS232 levels for loads up to 3k.
Slew rates are controlled for lightly loaded lines. Output
current capability is sufficient for load conditions up to
2500pF. Outputs are in a high impedance state when in
shutdown mode, VCC = 0V, or when the DRIVER DISABLE
pin is active. Outputs are fully short-circuit protected from
V– + 30V to V+ – 30V. Applying higher voltages will not
damage the device if the overdrive is moderately current
limited. Short circuits on one output can load the power
supply generator and may disrupt the signal levels of the
other outputs. The driver outputs are protected against
ESD to ±15kV for human body model discharges, ±8kV
for IEC 1000-4-2 contact mode discharges and ±15kV for
IEC 1000-4-2 air gap discharges.
RX IN: Receiver Inputs. These pins accept RS232 level
signals (±30V) into a protected 5k terminating resistor.
The receiver inputs are protected against ESD to ±15kV for
human body model discharges, ±8kV for IEC 1000-4-2
contact mode discharges and ±15kV for IEC 1000-4-2 air
gap discharges. Each receiver provides 0.4V of hysteresis
for noise immunity. Open receiver inputs assume a logic
low state.
RX OUT: Receiver Outputs with TTL/CMOS Voltage Levels. Outputs RX1, RX2, RX3, and RX4 are in a high
impedance state when in shutdown mode to allow data
line sharing. Outputs, including LOW-Q RX OUT, are fully
short-circuit protected to ground or VCC with the power
on, off, or in shutdown mode.
LOW Q-CURRENT RX IN: Low Power Receiver Input. This
special receiver remains active when the part is in shutdown mode, consuming typically 60µA. This receiver has
the same 5k input impedance and ±10kV ESD protection
characteristics as the other receivers.
LOW Q-CURRENT RX OUT: Low Power Receiver Output.
This pin produces the same TTL/CMOS output voltage
levels as receivers RX1, RX2, RX3, and RX4 with slightly
decreased speed and short-circuit current. Data rates to
120kbaud are supported by this receiver.
U
ESD PROTECTIO
The RS232 line inputs of the LT1237 have on-chip protection from ESD transients up to ±15kV for human body
discharges, ±8kV for IEC 1000-4-2 contact mode discharges and ±15V for IEC 1000-4-2 air gap discharges.
The protection structures act to divert the static discharge
safely to system ground. In order for the ESD protection to
function effectively, the power supply and ground pins of
the LT1237 must be connected to ground through low
impedances. The power supply decoupling capacitors and
charge pump storage capacitors provide this low impedance in normal application of the circuit. The only constraint is that low ESR capacitors must be used for
bypassing and charge storage. ESD testing must be done
with pins VCC, VL, V+, V– and GND shorted to ground or
connected with low ESR capacitors.
6
1µF
RS232
LINE PINS
PROTECTED
TO ±10kV
V
5V V
0.1µF
0.2µF
DRIVER 1 OUT
RX1 IN
DRIVER 2 OUT
RX2 IN
RX3 IN
RX4 IN
DRIVER 3 OUT
RX5 IN (LOW-Q)
ON/OFF
ESD Test Circuit
+
1
2
CC
3
4
5
6
7
8
9
10
11
12
13
14
LT1237
–
V
28
27
26
25
DRIVER 1 IN
24
RX1 OUT
23
DRIVER 2 IN
22
RX2 OUT
21
RX3 OUT
20
RX4 OUT
19
DRIVER 3 IN
18
RX5 OUT (LOW-Q)
17
GND
16
DRIVER DISABLE
15
0.1µF
0.2µF
1237 TC01
Page 7
LT1237
(
)
PPLICATI
A
U
O
S
I FOR ATIO
WU
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Storage Capacitor Selection
The V+ and V– storage capacitors must be chosen carefully to insure low ripple and stable operation. The LT1237
charge pump operates in a power efficient Burst Mode
TM
operation. When storage capacitor voltage drops below a
preset threshold, the oscillator is gated on until V+ and V
–
are boosted up to levels exceeding a second threshold.
The oscillator then turns off, and current is supplied from
the V+ and V– storage capacitors.
The V– potential is monitored to control charge pump
operation. It is therefore important to insure lower V
+
ripple than V– ripple, or erratic operation of the charge
pump will result. Proper operation is insured in most
applications by choosing the V+ filter capacitor to be at
least 5 times the V– filter capacitor value. If V+ is more
heavily loaded than V–, a larger ratio may be needed.
The V– filter capacitor should be selected to obtain low
ripple when the drivers are loaded, forcing the charge
pump into continuous mode. A minimum value 0.1µF is
suggested.
Do not attempt to reduce V– ripple when the charge pump
is in discontinuous Burst Mode operation. The ripple in
this mode is determined by internal comparator thresholds. Larger storage capacitor values increase the burst
period, and do not reduce ripple amplitude.
Power Saving Operational Modes
The LT1237 has both shutdown and driver disable operating modes. These operating modes can optimize power
consumption based upon applications needs.
The On/Off shutdown control turns off all circuitry except
for Low-Q RX5. When RX5 detects a signal, this information can be used to wake up the system for full operation.
If more than one line must be monitored, the driver disable
mode provides a power efficient operating option. The
driver disable mode turns off the charge pump and RS232
drivers, but keeps all five receivers active. Power consumption in driver disable mode is 3mA from VCC.
Burst Mode is a trademark of Linear Technology Corporation
PACKAGE DESCRIPTIO
0.205 – 0.212**
(5.20 – 5.38)
0.005 – 0.009
(0.13 – 0.22)
**
0.600 – 0.625
(15.240 – 15.875)
0.009 – 0.015
(0.229 – 0.381)
+0.035
0.625
–0.015
+0.889
15.87
()
–0.381
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH
0.015
(0.381)
MIN
0.022 – 0.037
(0.55 – 0.95)
*
DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
DIMENSIONS DO NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
0.150 ± 0.005
(3.810 ± 0.127)
0.125
(3.175)
MIN
0.035 – 0.080
(0.889 – 2.032)
0.100 ± 0.010
(2.540 ± 0.254)
0.254mm
U
Dimensions in inches (millimeters) unless otherwise noted.
G Package
28-Lead Plastic SSOP (0.209)
° – 8°
0
0.045 – 0.065
(1.143 – 1.651)
(LTC DWG # 05-08-1640)
0.0256
(0.65)
BSC
0.010 – 0.015
(0.25 – 0.38)
0.002 – 0.008
(0.05 – 0.21)
NW Package
28-Lead PDIP (Wide 0.600)
(LTC DWG # 05-08-1520)
0.018 ± 0.003
(0.457 ± 0.076)
0.068 – 0.078
(1.73 – 1.99)
0.070
(1.778)
TYP
0.505 – 0.560*
(12.827 – 14.224)
0.397 – 0.407*
(10.07 – 10.33)
2526 22 2120 19181716 1523242728
12345678 9 10 1112 1413
27
12
3
4
1.455*
(36.957)
567
MAX
0.301 – 0.311
(7.65 – 7.90)
G28 SSOP 0694
2021222423252628
8910
19
11 12 13 14
15
1718
16
N28 1197
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
7
Page 8
LT1237
PACKAGE DESCRIPTIO
U
Dimensions in inches (millimeters) unless otherwise noted.
SW Package
28-Lead Plastic Small Outline (Wide 0.300)
(LTC DWG # 05-08-1620)
0.291 – 0.299**
(7.391 – 7.595)
0.009 – 0.013
(0.229 – 0.330)
NOTE:
1. PIN 1 IDENT, NOTCH ON TOP AND CAVITIES ON THE BOTTOM OF PACKAGES ARE THE MANUFACTURING OPTIONS.
THE PART MAY BE SUPPLIED WITH OR WITHOUT ANY OF THE OPTIONS
DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
*
DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
**
NOTE 1
0.016 – 0.050
(0.406 – 1.270)
A
PPLICATITYPICAL
0.010 – 0.029
(0.254 – 0.737)
° – 8° TYP
0
× 45°
0.093 – 0.104
(2.362 – 2.642)
0.050
(1.270)
TYP
U
O
0.014 – 0.019
(0.356 – 0.482)
TYP
Typical Mouse Driving Application
MOUSE
V
LOGIC
OPTICS
V
+
(1)
–
(9)
(5)
1.0µF
2 × 0.1µF
DCD
DSR
RX
RTS
TX
CTS
DTR
RI
0.037 – 0.045
(0.940 – 1.143)
0.004 – 0.012
(0.102 – 0.305)
+
V
5V V
CC
DRIVER 1 OUT
RX1 IN
DRIVER 2 OUT
RX2 IN
RX3 IN
RX4 IN
DRIVER 3 OUT
RX5 IN (LOW-Q)
ON/OFF
10
11
12
13
14
NOTE 1
1
2
3
4
5
6
7
8
9
2526
2728
2345678
1
LT1237
0.697 – 0.712*
(17.70 – 18.08)
22 21 20 19 181716 152324
910
–
V
28
27
26
DRIVER 1 IN
25
RX1 OUT
24
DRIVER 2 IN
23
RX2 OUT
22
RX3 OUT
21
RX4 OUT
20
DRIVER 3 IN
19
RX5 OUT (LOW-Q)
18
GND
17
DRIVER DISABLE
16
15
11 12
2 × 0.1µF
0.394 – 0.419
(10.007 – 10.643)
S28 (WIDE) 0996
1413
LOGIC “0”
LOGIC “0”
MOUSE DATA
LOGIC “1”
0.1µF
DB9
RELATED PARTS
PART NUMBER DESCRIPTION COMMENTS
LTC®485 Low Power RS485 Transceiver
LT1137A 3Dx/5Rx RS232 Transceiver 15kV ESD
LTC1387 RS232/RS485 Multiprotocol Transceiver
LT1780/LT1781 2Dx/2Rx RS232 Transceiver 15kV ESD
LT1785/LT1791 60V Fault Tolerant RS485 Transceiver 15kV ESD
Linear Technology Corporation
8
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear-tech.com
1237 TA03
1237fa LT/TP 0799 2K REV A • PRINTED IN USA
LINEAR TECHNOLOGY CORPORATION 1992
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