LT1332 LINER [Linear Technology], LT1332 Datasheet - Page 6

• Manufacturer Part Number: LT1332
• Description: Wide Supply Range Low Power RS232 Transceiver with 12V VPP Output for Flash Memory
• Manufacturer: LINER [Linear Technology]

PI FU CTIO S
LT1332
capacitors work well in this application. When V
powered from an external supply, the filter capacitor can
be considerably smaller (C 0.1 F). Ceramic capacitors
work well under these conditions. V
than –13.2V and less than – 6.5V.
C
used with a switching regulator, a charge pump capacitor
should be connected from the regulator’s switch pin to the
C
effective series resistance to maintain good charge pump
efficiency. Low ESR tantalum capacitors (ESR < 2 ) work
well in this application. The C
when V
DRIVER IN: RS232 Driver Input Pins. Inputs are TTL/
CMOS compatible, with threshold set to 1.2V. Unused
inputs should not float; tie them to V
DRIVER OUT: Driver Outputs at RS232 Voltage Levels.
Outputs are in a high impedance state when in SHUT-
DOWN mode, or V
protected from V
off or SHUTDOWN. Typical breakdowns are
Applying higher voltages will not damage the device if
the overdrive is moderately current limited. Although
the outputs are protected, short circuits on one output
ESD PROTECTIO
The RS232 line inputs of the LT1332 have on-chip protec-
tion from ESD transients up to 10kV. The protection
structures act to divert the static discharge safely to
system ground. In order for the ESD protection to function
effectively, the power supply and ground pins of the
LT1332 must be connected to ground through low imped-
ances. The power supply decoupling capacitors and charge
pump storage capacitors provide this low impedance in
normal applications of the circuit. The only constraint is
that low ESR capacitors must be used for bypassing and
charge storage. ESD testing must be done with pins V
V
ESR capacitors.
6
–
–
+
: Commutating Capacitor Input. When the LT1332 is
, V
U
pin. Make the external capacitor 1 F or larger with low
–
and GND shorted to ground or connected with low
–
is powered from an external supply.
U
–
CC
+ 30V to V
U
= 0V. Outputs are fully short-circuit
U
+
–
– 30V with the power on,
pin should be left open
–
should be greater
CC
.
45V.
–
CC
is
,
can load the power supply generator and may disrupt
the signal levels of the other outputs. The driver outputs
are protected against ESD to 10kV for human body
model discharges.
RX IN: Receiver Inputs. These pins accept RS232 level
signals ( 5V to 30V) into a protected 5k terminating
resistor. The receiver inputs are protected against ESD to
provides 0.4V of hysteresis for noise immunity. The re-
ceiver thresholds are specified at V
varies from 2V to 6V, the lower threshold increases
about 3V. Regardless of these shifts, the device provides
accurate data from valid RS232 input signals. A graph in
the performance characteristics section shows typical
changes in the thresholds. The active receiver (RXA, Pin
10, S Package) remains functional in SHUTDOWN.
RX OUT: Receiver Outputs with TTL/CMOS Voltage Lev-
els. Outputs are in a high impedance stage when in
SHUTDOWN mode to allow data line sharing. Outputs are
fully short-circuit protected to ground or V
power on, off or in SHUTDOWN mode. The active receiver
(RXA, Pin 15, S Package) remains functional in SHUT-
DOWN.
12V
PROTECTED
3V
10kV for human body model discharges. Each receiver
LINE PINS
TO ±10kV
RS232
0.1 F
0.1 F
DRIVER OUT
DRIVER OUT
DRIVER OUT
RXA IN
3V V
RX IN
RX IN
RX IN
RX IN
NC
V
C
CC
+
–
10
11
12
1
2
3
4
5
6
7
8
9
ESD Test Circuit
LT1332
LT1332 • TC
24
23
22
21
20
19
18
17
16
15
14
13
CC
V
GND
DRIVER IN
RX OUT
DRIVER IN
RX OUT
RX OUT
RX OUT
DRIVER IN
RXA OUT
RS232 ON/OFF
GND
–
= 3V. When V
CC
with the
0.1 F
–12V
CC