7
LTC1334
PI FU CTIO S
U
UU
RB2 (Pin 16): Receiver Output.
RA2 (Pin 17): Receiver Output.
DZ2/DE2 (Pin 18): RS232 Driver Input in RS232 Mode.
RS485 Driver Enable with internal pull-up in RS485 mode.
DY2 (Pin 19): Driver Input.
ON/OFF (Pin 20): A high logic input enables the transceiv-
ers. A low puts the device into shutdown mode and
reduces ICC to 10A. This pin has an internal pull-up.
LB (Pin 21): Loopback Control Input. A low logic level
enables internal loopback connections. This pin has an
internal pull-up.
DY1 (Pin 22): Driver Input.
DZ1/DE1 (Pin 23): RS232 Driver Input in RS232 Mode.
RS485 Driver Enable with internal pull-up in RS485 mode.
RA1 (Pin 24): Receiver Output.
RB1 (Pin 25): Receiver Output.
VCC (Pin 26): Positive Supply; 4.75V ≤ VCC ≤ 5.25V
C2– (Pin 27): Commutating Capacitor C2 Negative Termi-
nal. Requires 0.1
F external capacitor between Pins 27
and 28.
C2+ (Pin 28): Commutating Capacitor C2 Positive Terminal.
FU CTIO TABLES
UU
RS485 Driver Mode
INPUTS
OUTPUTS
ON/OFF
SEL
DE
D
CONDITIONS
Z
Y
1
0
No Fault
0
1
No Fault
1
0
1
X
Thermal Fault
Z
11
0
X
Z
01
X
Z
RS232 Driver Mode
INPUTS
OUTPUTS
ON/OFF
SEL
D
CONDITIONS
Y, Z
1
0
No Fault
1
0
1
No Fault
0
1
0
X
Thermal Fault
Z
00
X
Z
RS485 Receiver Mode
INPUTS
OUTPUTS
ON/OFF
SEL
B – A
RA
RB*
1
< – 0.2V
0
1
> 0.2V
1
Inputs Open
1
01
X
Z
*See Note 5 of Electrical Characteristics table.
RS232 Receiver Mode
INPUTS
OUTPUTS
ON/OFF
SEL
A, B
RA, RB
10
0
1
10
1
0
1
0
Inputs Open
1
00
X
Z
1
28
C2+
C2–
C1+
VEE
RB2
RA2
DZ2/DE2
DY2
ON/OFF
LB
DY1
DZ1/DE1
RA1
RB1
VCC
14
15
13
12
11
10
9
8
7
6
5
4
3
2
16
17
18
19
20
21
22
23
24
25
26
27
GND
A2
B2
Y2
Z2
SEL2
SEL1
Z1
Y1
B1
A1
VDD
C1–