LT1780_15 Datasheet, PDF (1/12 Pages) Linear Technology – Low Power 5V RS232 Dual Driver/Receiver with 15kV ESD Protection

FEATURES
s _{10mA Max Supply Current}
s _{ESD Protection to IEC 1000-4-2 Level 4}
±15kV Air Gap, ±8kV Contact
s _{Uses Small Capacitors: 0.1µF}
s _{120kBaud Operation for RL = 3k, CL = 2500pF}
s _{250kBaud Operation for RL = 3k, CL = 1000pF}
s _{Outputs Withstand ±30V Without Damage}
s _{CMOS Comparable Low Power: 40mW}
s _{Operates from a Single 5V Supply}
s _{Rugged Bipolar Design}
s _{Outputs Assume a High Impedance State When Off}
or Powered Down
s _{Meets All RS232 Specifications}
s _{Available With or Without Shutdown}
s _{Absolutely No Latch-up}
APPLICATI S
s _{Portable Computers}
s _{Battery-Powered Systems}
s _{Power Supply Generator}
s _Terminals
s _Modems
TYPICAL APPLICATI
2
17
0.1µF
4
3
5
0.1µF
6
12
LOGIC
INPUTS
11
13
LOGIC
OUTPUTS
10
18
ON/OFF
LT1780
7
15
8
14
5k
9
5k ₁₆
5V INPUT
0.1µF
V⁺ OUT
0.1µF
V ^– OUT
RS232 OUTPUT
RS232 OUTPUT
RS232 INPUT
RS232 INPUT
1780/81 • TA01
LT1780/LT1781
Low Power 5V RS232
Dual Driver/Receiver with
±15kV ESD Protection
DESCRIPTIO
The LT^®1780/LT1781 are dual RS232 driver/receiver pairs
with integral charge pump to generate RS232 voltage
levels from a single 5V supply. Using only 0.1µF external
capacitors, these circuits consume only 40mW of power,
and can operate to 120kbaud even while driving heavy
capacitive loads. New ESD structures on the chip allow the
LT1780/LT1781 to survive ±15kV air gap and ±8kV con-
tact ESD tests per IEC 1000-4-2, eliminating the need for
costly TransZorbs^® on the RS232 line pins. The LT1780/
LT1781 are fully compliant with EIA RS232 standards.
Driver outputs are protected from overload, and can be
shorted to ground or up to ±30V without damage. During
SHUTDOWN or power-off conditions, driver and receiver
outputs are in a high impedance state, allowing line
sharing.
The LT1780/LT1781 are direct upgrades to the LT1180A/
LT1181A, LT1280A/LT1281A and LT1381 for applications
which require the utmost ESD protection.
The LT1781 is available in 16-pin DIP,SO and SW pack-
ages. The LT1780 is supplied in 18-pin DIP and SW
packages for applications which require SHUTDOWN.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TransZorb is a registered trademark of General Instruments, GSI.
DRIVER
OUTPUT
R_L = 3k
C_L = 2500pF
RECEIVER
RCO_L ^{U= T5P0UpTF}
INPUT
Output Waveforms
1780/81 • TA02
1