LT1537 Ver la hoja de datos (PDF) - Linear Technology
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LT1537 Datasheet PDF : 8 Pages
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LT1537
PI FU CTIO S
RX IN: Receiver Inputs. These pins accept RS232 level
signals (± 25V) into a protected 5k terminating resistor.
The receiver inputs are protected against ESD to ±5kV for
human body model 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 Lev-
els. Outputs are in a high impedance state when in shut-
down mode to allow data line sharing. Outputs are fully
short-circuit protected to ground or VCC with the power
on, off, or in shutdown mode.
U
ESD PROTECTIO
The RS232 line inputs of the LT1537 have on-chip protec-
tion from ESD transients up to ±5kV during shutdown or
power ON state. 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 LT1537 must be connected to
ground through low impedances. The power supply
decoupling capacitors and charge pump storage capaci-
tors 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, V+, V – and GND
shorted to ground or connected with low ESR capacitors.
ESD Test Circuit
+
0.1µF
V+ 1
+
5V VCC 2
0.1µF +
3
0.2µF
4
RS232
LINE PINS
PROTECTED
TO ± 5kV
5
DRIVER 1 OUT
RX1 IN 6
DRIVER 2 OUT 7
8
RX2 IN
9
RX3 IN
RX4 IN 10
11
DRIVER 3 OUT
12
RX5 IN
13
ON/OFF
14
LT1537
28 V–
27
0.1µF
26
0.2µF
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
17
GND
16
DRIVER DISABLE
15
LT1537 • ESD TC
U
TYPICAL APPLICATIO S
LT1537 Driving Remote Powered LTC1382
+
2 × 0.1µF
+
0.1µF
LOGIC
INPUT
LOGIC
OUTPUT
DRIVER
V+
VCC
LT1537 V–
DRIVER
DRIVER
RECEIVER
RECEIVER
ON/OFF = 5V
2 × 0.1µF
0.1µF
5.1V
0.1µF
0.1µF 0.1µF +
0.1µF +
RS232 OUTPUT
THREE
RECEIVERS
NOT USED
RS232 OUTPUT
VCC
V+
LTC®1382 V–
RECEIVER
RECEIVER
DRIVER
DRIVER
ON/OFF = 5V
0.1µF
0.1µF
LOGIC
OUTPUT
LOGIC
INPUT
LT1537 • TA03
6
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