LT1332CSW Linear Technology, LT1332CSW Datasheet - Page 6

• Manufacturer Part Number: LT1332CSW
• Description: IC TXRX RS232 W/12V VPP 24-SOIC
• Manufacturer: Linear Technology
• Type: Transceiverr

Specifications of LT1332CSW

• Number Of Drivers/receivers: 3/5
• Protocol: RS232
• Voltage - Supply: 2 V ~ 6 V
• Mounting Type: Surface Mount
• Package / Case: 24-SOIC (7.5mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

work well in this application. When V
an external supply, the filter capacitor can be considerably
smaller (C ≥ 0.1µF). Ceramic capacitors work well under
these conditions. V
less than – 6.5V.
C
used with a switching regulator, a charge pump capacitor
should be connected from the regulator’s switch pin to the
C
effective series resistance to maintain good charge pump
efficiency. Low ESR tantalum capacitors (ESR < 2Ω) work
well in this application. The C
when V
DRIVER IN: RS232 Driver Input Pins. Inputs are TTL/
CMOS compatible, with threshold set to 1.2V. Unused
inputs should not float; tie them to V
DRIVER OUT: Driver Outputs at RS232 Voltage Levels.
Outputs are in a high impedance state when in SHUT-
DOWN mode, or V
protected from V
off or SHUTDOWN. Typical breakdowns are ± 45V.
Applying higher voltages will not damage the device if
the overdrive is moderately current limited. Although
LT1332
PIN FUNCTIONS
The RS232 line inputs of the LT1332 have on-chip protection
from ESD transients up to ±10kV. 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 LT1332 must
be connected to ground through low impedances. The
power supply decoupling capacitors and charge pump
storage capacitors provide this low impedance in normal
applications 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 V
V
ESR capacitors.
6
ESD PROTECTION
–
–
–
: Commutating Capacitor Input. When the LT1332 is
pin. Make the external capacitor 1µF or larger with low
and GND shorted to ground or connected with low
–
is powered from an external supply.
–
CC
+ 30V to V
–
should be greater than –13.2V and
= 0V. Outputs are fully short-circuit
+
–
– 30V with the power on,
pin should be left open
–
CC
is powered from
.
CC
, V
+
,
the outputs are protected, 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 ±10kV for human body
model discharges.
RX IN: Receiver Inputs. These pins accept RS232 level
signals (± 5V to ±30V) into a protected 5k terminating
resistor. The receiver inputs are protected against ESD
to ±10kV for human body model discharges. Each re-
ceiver provides 0.4V of hysteresis for noise immunity.
The receiver thresholds are specified at V
V
about 3V. Regardless of these shifts, the device provides
accurate data from valid RS232 input signals. A graph
in the performance characteristics section shows typi-
cal changes in the thresholds. The active receiver (RXA,
Pin 10, S Package) remains functional in SHUTDOWN.
RX OUT: Receiver Outputs with TTL/CMOS Voltage Levels.
Outputs are in a high impedance stage when in SHUTDOWN
mode to allow data line sharing. Outputs are fully short-
circuit protected to ground or V
or in SHUTDOWN mode. The active receiver (RXA, Pin 15,
S Package) remains functional in SHUTDOWN.
12V
PROTECTED
3V
CC
LINE PINS
TO ±10kV
varies from 2V to 6V, the lower threshold increases
RS232
0.1µF
0.1µF
DRIVER OUT
DRIVER OUT
DRIVER OUT
RXA IN
3V V
RX IN
RX IN
RX IN
RX IN
NC
V
C
CC
+
–
10
11
12
1
2
3
4
5
6
7
8
9
ESD Test Circuit
LT1332
LT1332 • TC
CC
with the power on, off
24
23
22
21
20
19
18
17
16
15
14
13
V
GND
DRIVER IN
RX OUT
DRIVER IN
RX OUT
RX OUT
RX OUT
DRIVER IN
RXA OUT
RS232 ON/OFF
GND
–
CC
= 3V. When
0.1µF
–12V