LT1331_15 Datasheet, PDF (1/8 Pages) Linear Technology – 3V RS562 or 5V/3V RS232 Transceiver with One Receiver Active in Shutdown

LT1331
3V RS562 or 5V/3V RS232
Transceiver with One Receiver
Active in Shutdown
FEATURES
s _{RS232 Compatible 3V Operation}
s _{3V Logic Interface}
s _{ESD Protection Over ±10kV}
s _{120kbaud Operation for RL = 3k, CL = 2500pF}
s _{250kbaud Operation for RL = 3k, CL = 1000pF}
s _{One Low Power Receiver Remains Active While}
in Shutdown
s _{60µA Supply Current in Shutdown}
s _{Low Power Driver Disable Mode}
s _{Uses Small Capacitors: 0.1µF, 0.2µF}
s _{CMOS Comparable Low Power: 60mW}
s _{Easy PC Layout: Flowthrough Architecture}
s _{Rugged Bipolar Design}
s _{Outputs Assume a High Impedance State When}
Off or Powered Down
APPLICATI S
s _{Notebook Computers}
s _{Palmtop Computers}
DESCRIPTIO
The LT^®1331 is a 3-driver, 5-receiver RS232 transceiver
designed for 3V and mixed 3V/5V systems. Receivers
operate from 3V logic supply V_L, while the onboard charge
pump and drivers operate from 5V or 3V supply V_CC.
The transceiver has two shutdown modes. One mode
disables the drivers and the charge pump, the other shuts
down all circuitry except for one low power receiver which
can be used for ring detection. The V_CC supply may be shut
down while in ring detection mode. While shut down, the
drivers and receivers assume high impedance output
states.
The LT1331 is fully compliant with all EIA-RS232 specifi-
cations when V_CC = 5V. If V_CC = 3V, output drive levels are
compatible with all known interface circuits. Special bipo-
lar construction techniques protect the drivers and receiv-
ers beyond the fault conditions stipulated for RS232. The
RS232 I/O pins are resilient to multiple ±10kV ESD strikes.
An advanced driver output stage operates up to 120kbaud
while driving heavy capacitive loads.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATI
3.3V Operation
+
V⁺ 1
0.1µF
2
V_CC = 3.3V
+
3
2 × 0.1µF
4
TO LINE
DRIVER 1 OUT ⁵
RX1 IN ⁶
DRIVER 2 OUT ⁷
RX2 IN ⁸
9
RX3 IN
RX4 IN ¹⁰
11
DRIVER 3 OUT
RX5 IN (LOW-Q) ¹²
ON/OFF ¹³
3.3V V_L ¹⁴
LT1331
28 V ^–
27
0.1µF
26
2 × 0.1µF
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 (LOW-Q)}
17
GND
16
DRIVER DISABLE
15
NC
TO LOGIC
RING DETECT IN
µCONTROLLER
OR
µPROCESSOR
SHUTDOWN
CONTROL OUT
1331 TA01
RECEIVER
OUTPUT
C_L = 50pF
R
DRIVER
OUTPUT
R_L = 3k
C_L = 2500pF
INPUT
1331 TA02
1