LT1342_15 Datasheet, PDF (1/8 Pages) Linear Technology – 5V RS232 Transceiver with 3V Logic Interface

LT1342
5V RS232 Transceiver with
3V Logic Interface
FEATURES
s _{ESD Protection Over ±10kV}
s _{3V Logic Interface}
s _{Uses Small Capacitors: 0.1µF, 0.2µF}
s _{1µA Supply Current in Shutdown}
s _{Low Power Driver Disable Operating Mode}
s _{Pin Compatible with LT1137A}
s _{120kBaud Operation for RL = 3k, CL = 2500pF}
s _{250kBaud Operation for RL = 3k, CL = 1000pF}
s _{CMOS Comparable Low Power: 60mW}
s _{Operates from a 5V Supply and 3V Logic 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}
APPLICATI S
s _{Notebook Computers}
s _{Palmtop Computers}
DESCRIPTIO
The LT^®1342 is an advanced low power three-driver, five-
receiver RS232 transceiver. The LT1342 operates from a
5V supply and a 3V logic supply. Receiver outputs can
interface directly to 3V logic circuits. Included on the chip
is a shutdown pin for reducing supply current to near zero.
All receivers and drivers assume high impedance states
during shutdown.
The driver disable function provides additional control of
operating mode. When driver disable is high the charge
pump and drivers turn off. Receivers continue to operate
during driver disable.
New ESD structures on the chip allow the LT1342 to
survive multiple ±10kV strikes, eliminating the need for
costly TransZorbs^® on the RS232 line pins.
The LT1342 is fully compliant with all EIA RS232 specifi-
cations and operates in excess of 120kbaud even driving
heavy capacitive loads.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TransZorb is a registered trademark of General Instruments, GSI.
TYPICAL APPLICATI
V⁺ 1
0.1µF
5V V_CC ²
3
2 × 0.1µF
4
TO LINE
DRIVER 1 OUT ⁵
RX1 IN ⁶
7
DRIVER 2 OUT
RX2 IN ⁸
RX3 IN ⁹
RX4 IN ¹⁰
DRIVER 3 OUT ¹¹
RX5 IN ¹²
ON/OFF ¹³
14
3V V_L
LT1342
28 V ^–
27
0.1µF
26
2 × 0.1µF
25 _{DRIVER 1 IN}
24 _{RX1 OUT}
23
DRIVER 2 IN
22 _{RX2 OUT}
21
TO 3V LOGIC
RX3 OUT
20 _{RX4 OUT}
19 _{DRIVER 3 IN}
18
RX5 OUT
17
GND
16
DRIVER DISABLE
15 _NC
LT1342 • TA01
RECEIVER
OUTPUT
V_L = 3V
C_L = 50pF
DRIVER
ROUTPUT
R_L = 3k
C_L = 2500pF
INPUT
Output Waveforms
LT1342 • TA02
1