LT1237 Datasheet, PDF (1/8 Pages) Linear Technology – 5V RS232 Transceiver with Advanced Power Management and One Receiver Active in Shutdown

LT1237
5V RS232 Transceiver with
Advanced Power Management and
One Receiver Active in Shutdown
FEATURES
s _{One Receiver Remains Active While in Shutdown}
s _{ESD Protection over ±15kV}
s _{Uses Small Capacitors: 0.1µF, 0.2µF, 1.0µF}
s _{60µA Supply Current in Shutdown}
s _{Pin Compatible with LT1137A}
s _{120kBaud Operation for RL = 3k, CL = 2500pF}
s _{250kBaud Operation for RL = 3k, CL = 1000pF}
s _{Operates to 120kBaud}
s _{CMOS Comparable Low Power 30mW}
s _{Operates from a Single 5V Supply}
s _{Easy PC Layout—Flowthrough Architecture}
s _{Rugged Bipolar Design}
s _{Outputs Assume a High Impedance State When Off}
or Powered Down
s _{Absolutely No Latchup}
s _{Available in SO and SSOP Packages}
U
APPLICATIO S
s _{Notebook Computers}
s _{Palmtop Computers}
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 specifi-
cations. 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 receiv-
ers 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
V⁺ 1
1.0µF
2 × 0.1µF
5V V_CC ²
3
4
DRIVER 1 OUT ⁵
RX1 IN ⁶
DRIVER 2 OUT ⁷
TO
LINE
RX2 IN ⁸
RX3 IN ⁹
RX4 IN ¹⁰
DRIVER 3 OUT ¹¹
RX5 IN (LOW-Q) ¹²
ON/OFF 13
14
LT1237
28 V^–
27
0.1µF
RECEIVER
26
2 × 0.1µF
OUTPUT
25
DRIVER 1 IN
C_L = 50pF
24
RX1 OUT
DRIVER
23
DRIVER 2 IN
22
RX2 OUT
21
RX3 OUT
TO LOGIC
OUTPUT
R_L = 3k
RC^{L = 2500pF}
20
RX4 OUT
19 _{DRIVER 3 IN}
INPUT
18 RX5 OUT (LOW-Q)
RING DETECT IN
17 GND
16 ^DRIVER
DISABLE
µCONTROLLER OR
µPROCESSOR
15
SHUTDOWN
CONTROL OUT
LT1237 TA01
Output Waveforms
1237 TA02
1