LT1332_15 Datasheet, PDF (1/8 Pages) Linear Technology – Wide Supply Range Low Power RS232 Transceiver with 12V VPP Output for Flash Memory

LT1332
OBSOLETE:
FOR INFORMATION PURPOSES ONLY
Contact Linear Technology for Potential Replacement
FEATURES
Wide Supply Range
Low Power RS232 Transceiver with
12V VPP Output for Flash Memory
DESCRIPTION
n _{Generates Full RS232 Signal Levels from 3V Supply}
n _{12V VPP Output Available for Flash Memory}
n _{Useful with a Wide Variety of Switching Regulators}
n _{Low Supply Current: I(VCC) = 1mA}
n _{Wide Supply Range: 2V ≤ VCC ≤ 6V}
n _{ESD Protection Over ±10kV}
n _{Operates to 120k Baud}
n _{Outputs Assume a High Impedance State When Off}
or Powered Down
n _{One µPower Receiver Remains Active While in}
SHUTDOWN
n _{Flowthrough Architecture Eases PC Board Layout}
n _{40µA Supply Current in SHUTDOWN}
n _{Absolutely No Latch-Up}
n _{Available in SO and SSOP Packages}
APPLICATIONS
n _{Notebook and Palmtop Computers}
n _{Mouse Driver Circuits}
The LT1332 is a 3-driver/5-receiver RS232 transceiver,
designed to be used in conjunction with a switching
regulator. The LT1332 shares the regulator’s positive
output, while charge is capacitively pumped from the
regulator’s switch pin to the negative supply. Schottky
rectifiers built into the LT1332 simplify the charge
pump design.
The LT1332/LT1109A combination shown below generates
fully compliant RS232 signal levels from as little as 2V of
input supply. The switcher can deliver greater than 100mA
of output current, making the LT1332 an excellent choice
for mouse driver circuits.
Advanced driver output stages operate up to 120k baud
while driving heavy capacitive loads. New ESD structures
on chip make the LT1332 resilient to multiple ±10kV strikes,
eliminating costly transient suppressors.
A shutdown pin disables the transceiver except for one
receiver which remains active for detecting incoming
RS232 signals. When shut down, the disabled drivers and
receivers assume high impedance output states.
TYPICAL APPLICATION
LT1332 Powered from an LT1109A Micropower Switching Regulator
Configured for Flash Memory
STANDARD FLASH MEMORY VPP GENERATOR
SWITCHER
V_IN 2 AA
BATTERIES
UP TO 6V
L1**
33µH
22µF*
V _IN
SW
LT1109A-12
ON/OFF
SW
ON/OFF
SENSE
GND PGND
* AVX TAJE226K035
** SUMIDA CD54-330N (708-956-0666)
12V VPP
MBRS130T3 ^OUTPUT
22µF*
3V
RS232
V_CC
+
1µF
V⁺ 1
C^– 2
3
4
5
RS232 ⁶
SIDE ₇
8
9
10
11
NC
12
0.1µF
LT1332
24 V^–
23
+ ^10µF
22
21
20
19 LOGIC
SIDE
18
17
16
15
14 RS232
13 ^ON/OFF
DRIVER
INPUT
DRIVER
OUTPUT
R_L = 3k
C_L = 2500pF
RECEIVER
OUTPUT
C_L = 50pF
LT1332 • TA01
Output Waveforms
LT1332 • TA02
1