LTC488/LTC489
Quad RS485 Line Receiver
FEATURES
s
s
s
s
DESCRIPTIO
s
s
s
s
s
Low Power: I
CC
= 7mA Typ
Designed for RS485 or RS422 Applications
Single 5V Supply
– 7V to 12V Bus Common Mode Range Permits
±7V
Ground Difference Between Devices on the Bus
60mV Typical Input Hysteresis
Receiver Maintains High Impedance in Three-State or
with the Power Off
28ns Typical Receiver Propagation Delay
Pin Compatible with the SN75173 (LTC488)
Pin Compatible with the SN75175 (LTC489)
The LTC
®
488 and LTC489 are low power differential bus/
line receivers designed for multipoint data transmission
standard RS485 applications with extended common mode
range (12V to – 7V). They also meet the requirements of
RS422.
The CMOS design offers significant power savings over its
bipolar counterpart without sacrificing ruggedness against
overload or ESD damage.
The receiver features three-state outputs, with the receiver
output maintaining high impedance over the entire com-
mon mode range.
The receiver has a fail-safe feature which guarantees a
high output state when the inputs are left open.
Both AC and DC specifications are guaranteed 4.75V to
5.25V supply voltage range.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATI
s
s
S
Low Power RS485/RS422 Receivers
Level Translator
TYPICAL APPLICATI
EN EN
EN
2
4
DI
DRIVER
1/4 LTC486
120Ω
120Ω
1
RECEIVER
1/4 LTC488
4000 FT 24 GAUGE TWISTED PAIR
EN12
EN12
2
DI
DRIVER
1/4 LTC487
120Ω
120Ω
1
4000 FT 24 GAUGE TWISTED PAIR
4
RECEIVER
1/4 LTC489
3
RO
U
EN
12
3
RO
LTC488/9 TA01
UO
UO
1
LTC488/LTC489
ABSOLUTE
AXI U
RATI GS
Supply Voltage (V
CC
) .............................................. 12V
Control Input Currents ........................ – 25mA to 25mA
Control Input Voltages ................ – 0.5V to (V
CC
+ 0.5V)
Receiver Input Voltages ........................................
±14V
Receiver Output Voltages ........... – 0.5V to (V
CC
+ 0.5V)
PACKAGE/ORDER I FOR ATIO
TOP VIEW
B1
A1
RO1
EN
RO2
A2
B2
GND
1
2
3
4
5
6
7
8
R
R
R
R
16 V
CC
15 B4
14 A4
13 RO4
12 EN
11 RO3
10 A3
9
B3
ORDER PART
NUMBER
LTC488CN
LTC488CS
LTC488IN
LTC488IS
N PACKAGE
16-LEAD PLASTIC DIP
S PACKAGE
16-LEAD PLASTIC SOL
T
JMAX
= 150°C,
θ
JA
= 70°C/W (N PKG)
T
JMAX
= 150°C,
θ
JA
= 90°C/W (S PKG)
Consult factory for Military grade parts.
DC ELECTRICAL CHARACTERISTICS
V
CC
= 5V (Notes 2, 3), unless otherwise noted.
SYMBOL
V
INH
V
INL
I
IN1
I
IN2
V
TH
∆V
TH
V
OH
V
OL
I
OZR
I
CC
R
IN
I
OSR
t
PLH
t
PHL
t
SKD
PARAMETER
Input High Voltage
Input Low Voltage
Input Current
Input Current (A, B)
Differential Input Threshold Voltage for Receiver
Receiver Input Hysteresis
Receiver Output High Voltage
Receiver Output Low Voltage
Three-State Output Current at Receiver
Supply Current
Receiver Input Resistance
Receiver Short-Circuit Current
Receiver Input to Output
Receiver Input to Output
| t
PLH
– t
PHL
|
Differential Receiver Skew
CONDITIONS
EN, EN, EN12, EN34
EN, EN, EN12, EN34
EN, EN, EN12, EN34
V
CC
= 0V or 5.25V, V
IN
= 12V
V
CC
= 0V or 5.25V, V
IN
= – 7V
– 7V
≤
V
CM
≤
12V
V
CM
= 0V
I
O
= – 4mA, V
ID
= 0.2V
I
O
= 4mA, V
ID
= – 0.2V
V
CC
= Max 0.4V
≤
V
O
≤
2.4V
No Load, Digital Pins = GND or V
CC
– 7V
≤
V
CM
≤
12V, V
CC
= 0V
0V
≤
V
O
≤
V
CC
C
L
= 15pF (Figures 1, 3)
C
L
= 15pF (Figures 1, 3)
C
L
= 15pF (Figures 1, 3)
q
q
q
q
q
q
q
q
q
q
q
q
q
q
2
U
U
W
W W
U
W
(Note 1)
Operating Temperature Range
LTC488C/LTC489C ................................. 0°C to 70°C
LTC488I/LTC489I .............................. – 40°C to 85°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
TOP VIEW
B1
A1
RO1
EN12
RO2
A2
B2
GND
1
2
3
4
5
6
7
8
R
R
R
R
16 V
CC
15 B4
14 A4
13 RO4
12 EN34
11 RO3
10 A3
9
B3
ORDER PART
NUMBER
LTC489CN
LTC489CS
LTC489IN
LTC489IS
N PACKAGE
16-LEAD PLASTIC DIP
S PACKAGE
16-LEAD PLASTIC SOL
T
JMAX
= 150°C,
θ
JA
= 70°C/W (N PKG)
T
JMAX
= 150°C,
θ
JA
= 90°C/W (S PKG)
MIN
2.0
TYP
MAX
0.8
±2
1.0
– 0.8
UNITS
V
V
µA
mA
mA
V
mV
V
– 0.2
60
3.5
0.2
0.4
±1
7
12
7
12
12
28
28
4
85
55
55
10
V
µA
mA
kΩ
mA
ns
ns
ns
LTC488/LTC489
DC ELECTRICAL CHARACTERISTICS
V
CC
= 5V
±
5% (Notes 2, 3), unless otherwise noted.
SYMBOL
t
ZL
t
ZH
t
LZ
t
HZ
PARAMETER
Receiver Enable to Output Low
Receiver Enable to Output High
Receiver Disable from Low
Receiver Disable from High
CONDITIONS
C
L
= 15pF (Figures 2, 4) S1 Closed
C
L
= 15pF (Figures 2, 4) S2 Closed
C
L
= 15pF (Figures 2, 4) S1 Closed
C
L
= 15pF (Figures 2, 4) S2 Closed
q
q
q
q
MIN
TYP
30
30
30
30
MAX
60
60
60
60
UNITS
ns
ns
ns
ns
The
q
denotes specifications that apply over the operating temperature
range.
Note 1:
Absolute Maximum Ratings are those beyond which the safety of
the device may be impaired.
Note 2:
All currents into device pins are positive; all currents out of device
pins are negative. All voltages are referenced to device ground unless
otherwise specified.
Note 3:
All typicals are given for V
CC
= 5V and T
A
= 25°C.
TYPICAL PERFOR A CE CHARACTERISTICS
Receiver Output Low Voltage vs
Temperature at I = 8mA
0.9
0.8
0.7
4.8
4.6
4.4
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
0.6
0.5
0.4
0.3
0.2
0.1
0
–50
–25
0
75
50
25
TEMPERATURE (°C)
100
125
Receiver Output High Voltage vs
Output Current at T
A
= 25°C
–18
–16
36
32
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
–14
–12
–10
–8
–6
–4
–2
0
5
4
3
OUTPUT VOLTAGE (V)
488 G03
U W
Receiver Output High Voltage vs
Temperature at I = 8mA
4.2
4.0
3.8
3.6
3.4
3.2
3.0
–50
–25
0
75
50
25
TEMPERATURE (°C)
100
125
488 G01
488 G02
Receiver Output Low Voltage vs
Output Current at T
A
= 25°C
28
24
20
16
12
8
4
0
2
0
0.5
1.5
1.0
OUTPUT VOLTAGE (V)
2.0
488 G04
3
LTC488/LTC489
TYPICAL PERFOR A CE CHARACTERISTICS
TTL Input Threshold vs
Temperature
1.63
INPUT THRESHOLD VOLTAGE (V)
1.61
4
SUPPLY CURRENT (mA)
–25
0
75
25
50
TEMPERATURE (°C)
100
125
1.59
TIME (ns)
1.57
1.55
–50
–25
0
75
25
50
TEMPERATURE (°C)
PI FU CTIO S
B 1 (Pin 1)
Receiver 1 Input.
A1 (Pin 2)
Receiver 1 Input.
RO1 (Pin 3)
Receiver 1 Output. If the receiver output is
enabled, then if A > B by 200mV, RO1 will be high. If
A < B by 200mV, then RO1 will be low.
EN (Pin 4) (LTC488)
Receiver Output Enabled. See
Function Table for details.
EN12 (Pin 4) (LTC489)
Receiver 1, Receiver 2 Output
Enabled. See Function Table for details.
RO2 (Pin 5)
Receiver 2 Output. Refer to RO1.
A2 (Pin 6)
Receiver 2 Input.
B2 (Pin 7)
Receiver 2 Input.
GND (Pin 8)
Ground Connection.
B3 (Pin 9)
Receiver 3 Input.
A3 (Pin 10)
Receiver 3 Input.
RO3 (Pin 11)
Receiver 3 Output. Refer to RO1.
EN (Pin 12)(LTC488)
Receiver Output Disabled. See
Function Table for details.
EN34 (Pin 12)(LTC489)
Receiver 3, Receiver 4 output
enabled. See Function Table for details.
RO4 (Pin 13)
Receiver 4 Output. Refer to RO1.
A4 (Pin 14)
Receiver 4 Input.
B4 (Pin 15)
Receiver 4 Input.
V
CC
(Pin 16)
Positive Supply; 4.75V
≤
V
CC
≤
5.25V.
4
U W
100
488 G05
Receiver
|
t
PLH
– t
PHL
|
vs
Temperature
5
7.0
Supply Current vs Temperature
6.6
3
6.2
2
5.8
125
1
–50
5.4
–50
–25
0
75
25
50
TEMPERATURE (°C)
100
125
488 G06
488 G07
U
U
U
LTC488/LTC489
FU CTIO TABLES
LTC488
DIFFERENTIAL
A–B
V
ID
≥
0.2V
–0.2V < V
ID
< 0.2V
V
ID
≤
0.2V
X
EN
H
X
H
X
H
X
L
ENABLES
EN
X
L
X
L
X
L
H
OUTPUT
RO
H
H
?
?
L
L
Z
TEST CIRCUITS
100pF
A
D
DRIVER
54Ω
100pF
B
RECEIVER
RO
C
L
U
U
LTC489
DIFFERENTIAL
A–B
V
ID
≥
0.2V
–0.2V < V
ID
< 0.2V
V
ID
≤
0.2V
X
ENABLES
EN12 or EN34
H
H
H
L
OUTPUT
RO
H
?
L
Z
H: High Level
L: Low Level
X: Irrelevant
?: Indeterminate
Z: High Impedance (Off)
488/9 F01
Figure 1. Receiver Timing Test Circuit
Note:
The input pulse is supplied by a generator having the following characteristics:
f = 1MHz, Duty Cycle = 50%, t
r
< 10ns, t
f
≤
10ns, Z
OUT
= 50Ω
S1
RECEIVER
OUTPUT
C
L
1k
S2
1k
V
CC
488/9 F02
Figure 2. Receiver Enable and Disable Timing Test Circuit
5
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