LT1537 Datasheet, PDF (1/8 Pages) Linear Technology – Advanced Low Power 5V RS232 Transceiver with Small Capacitors

LT1537
Advanced Low Power
5V RS232 Transceiver with
Small Capacitors
FEATURES
s _{Low Cost}
s _{Uses Small Capacitors: 0.1µF, 0.2µF}
s _{1µA Supply Current in Shutdown}
s _{120kBaud Operation for RL = 3k, CL = 2500pF}
s _{250kBaud Operation for RL = 3k, CL = 1000pF}
s _{CMOS Comparable Low Power: 40mW}
s _{Operates from a Single 5V Supply}
s _{Easy PC Layout: Flow-through Architecture}
s _{Rugged Bipolar Design}
s _{Outputs Assume a High Impedance State When Off}
or Powered Down
s _{Improved Protection: RS232 I/O Lines Can Be Forced}
to ±25V Without Damage
s _{Output Overvoltage Does Not Force Current Back}
into Supplies
s _{Absolutely No Latch-Up}
s _{Available in SO Package}
APPLICATI S
s _{Notebook Computers}
s _{Palmtop Computers}
DESCRIPTIO
The LT ^®1537 is a three-driver, five-receiver RS232 trans-
ceiver, pin compatible with the LT1137A, offering perfor-
mance improvements and two shutdown modes. The
LT1537’s charge pump is designed for extended compli-
ance and can deliver over 35mA of load current. Supply
current is typically 8mA, competitive with similar CMOS
devices. An advanced driver output stage operates up to
250kbaud while driving heavy capacitive loads.
The LT1537 is fully compliant with all RS232 specifica-
tions. Special bipolar construction techniques protect the
drivers and receivers beyond the fault conditions stipu-
lated for RS232. Driver outputs and receiver inputs can be
shorted to ±25V without damaging the device or the
power supply generator. In addition, the RS232 I/O pins
are resilient to multiple ±5kV ESD strikes.
The transceiver has two shutdown modes. One mode
disables the drivers and the charge pump, the other shuts
down all circuitry. While shut down, the drivers and
receivers assume high impedance output states.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATI
+
V⁺ 1
0.1µF
5V V_CC ²
+
3
2 × 0.1µF
4
DRIVER OUT ⁵
RX IN ⁶
DRIVER OUT ⁷
TO
LINE
RX IN ⁸
RX IN ⁹
RX IN ¹⁰
DRIVER OUT ¹¹
RX IN ¹²
13
ON/OFF = 5V
14
LT1537
28 V^–
27
0.1µF
26
2 × 0.1µF
25
DRIVER IN
24
RX OUT
23 _{DRIVER IN}
22
RX OUT
21
RX OUT
20 _{RX OUT}
19
DRIVER IN
18 _{RX OUT}
17 GND
TO LOGIC
16 _DRIVER
15 ^DISABLE
LT1537 • TA01
RECEIVER
OUTPUT
C_L = 50pF
R DRIVER
OUTPUT
R_L = 3k
C_L = 2500pF
INPUT
Output Waveforms
LT1537 • TA02
1