LT1341 Linear Technology, LT1341 Datasheet - Page 6

• Manufacturer Part Number: LT1341
• Description: 5V RS232 Transceiver with One Receiver Active in Shutdown
• Manufacturer: Linear Technology

PI FU CTIO S
LT1341
V
–(2V
storage capacitor C
increase the size of the storage capacitor. With multiple
transceivers, the V
common filter capacitors.
C1
pins require two external capacitors C 0.2 F: one from
C1
effective series resistance should be less than 2 . For
C
application, although small value ceramic capacitors may
be used with a minimal reduction in charge pump compli-
ance. When a 12V supply is available, C1 may be omitted.
Connect the 12V supply to C1
should be decoupled with a 0.1 F ceramic capacitor.
DRIVER IN: RS232 Driver Input Pins. These inputs are
TTL/CMOS compatible. Tie unused inputs to V
DRIVER OUT: Driver Outputs at RS232 Voltage Levels.
Outputs are in a high impedance state when in shut-
down mode, V
pin is active. Outputs are fully short-circuit protected
from V
higher voltages will not damage the device if the over-
ESD PROTECTIO
The RS232 line inputs of the LT1341 have on-chip protec-
tion 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
LT1341 must be connected to ground through low imped-
ances. 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 V
V
ESR capacitors.
6
–
+
, V
: Negative Supply Output (RS232 Drivers). V
+
+
U
, C1
to C1
1 F, low ESR tantalum capacitors work well in this
CC
–
and GND shorted to ground or connected with low
OUT
–
– 2.5V). This pin requires an external charge
, C2
–
U
, and another from C2
= V
+
, C2
CC
–
–
= 0V, or when the DRIVER DISABLE
+ 30V to V
: Commutating Capacitor Inputs. These
+
U
and V
0.1 F. To reduce supply ripple,
U
–
pins may be paralleled into
OUT
+
and V
+
to C2
= V
+
+
–
. The 12V supply
– 30V. Applying
. The capacitor’s
CC
.
–
CC
,
drive 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 10kV for
human body model 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 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 shut-
down mode to allow data line sharing. Outputs, including
LOW-Q RX OUT, are fully short-circuit protected to ground
or V
LOW Q-CURRENT RX IN: Low Power Receiver Input. This
special receiver remains active when the part is in shut-
down mode, consuming typically 60 A. This receiver has
the same input and 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 with slightly decreased speed and short-circuit
current.
PROTECTED
0.1 F
LINE PINS
TO 10kV
RS232
CC
with the power on, off, or in shutdown mode.
RX5 IN (LOW-Q)
DRIVER 1 OUT
DRIVER 2 OUT
DRIVER 3 OUT
0.1 F
0.2 F
ON/OFF
RX1 IN
RX2 IN
RX3 IN
RX4 IN
5V V
NC
V
CC
+
10
11
12
13
14
1
2
3
4
5
6
7
8
9
ESD Test Circuit
LT1341
28
27
26
25
24
23
22
21
20
19
18
17
16
15
DRIVER 1 IN
RX1 OUT
DRIVER 2 IN
RX2 OUT
RX3 OUT
RX4 OUT
DRIVER 3 IN
RX5 OUT (LOW-Q)
V
GND
DRIVER DISABLE
NC
–
0.1 F
0.2 F
LT1341 • ESD TC