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LTC1689CS#PBF

P1-P3P4-P6P7-P9P10-P12
4
LTC1688/LTC1689
16889fa
TYPICAL PERFORMANCE CHARACTERISTICS
UW
Propagation Delay
vs Temperature
TEMPERATURE (°C)
14
12
10
8
6
4
2
0
PROPAGATION DELAY (ns)
1688/89 G01
0 20 40 60 80 100
V
DI
= 0V TO 3V
R
DIFF
= 50Ω
C
L
= 25pF
V
DD
= 3V
V
DD
= 5V
Supply Current vs Data Rate
DATA RATE (Mbps)
250
200
150
100
50
0
SUPPLY CURRENT (mA)
1688/89 G03
0 20 40 60 80 100 120
V
DD
= 5V
R
DIFF
= 50Ω, PER DRIVER
C
L
= 25pF, PER DRIVER
T
A
= 25°C
4 DRIVERS
SWITCHING
1 DRIVER
SWITCHING
LOAD CAPACITANCE (pF)
14
12
10
8
6
4
2
0
PROPAGATION DELAY (ns)
1688/89 G02
0 10 20 30 40 50 60
V
DI
= 0V TO 3V
R
DIFF
= 50Ω
T
A
= 25°C
V
DD
= 3V
V
DD
= 5V
Propagation Delay
vs Load Capacitance
TEMPERATURE (°C)
OUTPUT CURRENT (µA)
1688/89 G04
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
0 20 40 60 80 100
V
DD
= 5V
V
OUT
= 12V
V
OUT
= –7V
TEMPERATURE (°C)
2.5
2.0
1.5
1.0
0.5
0
V
OD2
1688/89 G05
0 20 40 60 80 100
R
DIFF
= 50Ω
V
DD
= 5V
V
DD
= 3V
TEMPERATURE (°C)
180
160
140
120
100
80
60
40
20
0
I
DD
(mA)
1688/89 G06
0 20 40 60 80 100
V
DD
= 5V
R
DIFF
= 50Ω, PER DRIVER
0.1Mbps
1 DRIVER LOADED
4 DRIVERS LOADED
Three-State Output Current
I
DD
vs TemperatureV
OD2
vs Temperature
5
LTC1688/LTC1689
16889fa
PIN FUNCTIONS
UUU
DI1 (Pin 1): Driver 1 Input. Do not float.
DO1A (Pin 2): Driver 1 Noninverting Output.
DO1B (Pin 3): Driver 1 Inverting Output.
EN (Pin 4, LTC1688): High True Enable Pin, enables all
four drivers. A low on Pin 4 and a high on Pin 12 will put
all driver outputs into a high impedance state. See
Function Tables for details. Do not float.
EN12 (Pin 4, LTC1689): Enables Drivers 1 and 2. A low on
Pin 4 will put the outputs of drivers 1 and 2 into a high
impedance state. See Function Tables for details. Do not
float.
DO2B (Pin 5): Driver 2 Inverting Output.
DO2A (Pin 6): Driver 2 Noninverting Output.
DI2 (Pin 7): Driver 2 Input. Do not float.
GND (Pin 8): Ground Connection. A good ground plane is
recommended for all applications.
DI3 (Pin 9): Driver 3 Input. Do not float.
DO3A (Pin 10): Driver 3 Noninverting Output.
DO3B (Pin 11): Driver 3 Inverting Output.
ENB (Pin 12, LTC1688): Low True Enable Pin, enables all
four drivers. A low on Pin 4 and a high on Pin 12 will put
all driver outputs into a high impedance state. See
Function Tables for details. Do not float.
EN34 (Pin 12, LTC1689): Enables Drivers 3 and 4. A low
on Pin 12 will put the outputs of drivers 3 and 4 into a high
impedance state. See Function Tables for details. Do not
float.
DO4B (Pin 13): Driver 4 Inverting Output.
DO4A (Pin 14): Driver 4 Noninverting Output.
DI4 (Pin 15): Driver 4 Input. Do not float.
V
DD
(Pin 16): Power Supply Input. This pin should be
bypassed with a 0.1µF ceramic capacitor as close to the
pin as possible. Recommended: V
DD
= 3V to 5.25V.
FU CTIO TABLES
U
U
LTC1688
INPUTS OUTPUTS
DI EN ENB OUTA OUTB
HH X H L
LH X L H
HX L H L
LX L L H
X L H HI-Z HI-Z
LTC1689
INPUTS OUTPUTS
DI EN12/EN34 OUTA OUTB
HHHL
LHLH
X L HI-Z HI-Z
1688/89 TC03
OUTPUT
UNDER TEST
C
L
S1
500
DD
V
Ω
S2
1688/89 TC01
A
B
R
R
OD
V
OC
V
Figure 1. Driver DC Test Load
Figure 3. Driver Timing Test Load
DRIVER
1688/89 TC02
ENB (EN34)
DI
A
B
EN (EN12)
R
DIFF
C
L1
C
L2
Figure 2. Driver Timing Test Circuit
TEST CIRCUITS
6
LTC1688/LTC1689
16889fa
APPLICATIONS INFORMATION
WUU
U
The LTC1688/LTC1689 family of RS485 quad differential
drivers employs a novel architecture and fabrication pro-
cess that allows ultra high speed operation (100Mbps)
and Hot Swap capability while maintaining the ruggedness
of RS485 operation (three-state outputs can float from
–7V to 12V with a single 5V supply). Unlike typical CMOS
drivers whose propagation delay can vary as much as
500%, the propagation delay of the LTC1688/LTC1689
drivers will only vary by ±50% (a narrow ±4ns window).
This performance is achieved by designing the input stage
of each driver to have minimum propagation delay shift
over temperature and from part to part.
The LTC1688/LTC1689 have an ESD rating of 6kV human
body model.
50Mbps with 3V Operation
The LTC1688/LTC1689 are designed to operate with a 3V
power supply and still achieve 50Mbps operation (see
1688/89 F04
B
A
DI
V
O
V
O
–V
O
1/2 V
O
3V
0V
t
SKEW
1.5V
t
PLH
1.5V
t
PHL
1/2 V
O
V
DIFF
= V(A) – V(B)
90%
10%
t
f
90%
10%
t
SKEW
t
r
f = 1MHz; t
r
<
3ns; t
f
< 3ns
Figure 4. Driver Propagation Delays
1688/89 F05
A, B
EN
3V
0V
f = 1MHz; t
r
≤ 3ns; t
f
≤ 3ns
V
OL
V
OH
1.5V 1.5V
5V
OUTPUT NORMALLY LOW
t
ZL
1/2 V
DD
1/2 V
DD
t
LZ
0.5V
A, B
0V
t
ZH
OUTPUT NORMALLY HIGH
t
HZ
0.5V
Figure 5. Driver Enable and Disable Times
SWITCHI G TI E WAVEFOR S
UW W
Figure 6. 3V High Speed Data Transmission
20ns/DIV
2V/DIV
2V/DIV
5V/DIV
1688/89 F06
LTC1689 OUTPUT
RECEIVER OUTPUT
FAR END OF CABLE
Electrical Characteristics table for 3V DC and AC specifica-
tions). Figure 6 shows waveforms of an LTC1689 driving
a receiver using 100 feet of Category 5 UTP. Both parts are
operating at 3V supply.
P1-P3P4-P6P7-P9P10-P12

LTC1689CS#PBF

Mfr. #:
Buy LTC1689CS#PBF
Manufacturer:
Analog Devices Inc.
Description:
RS-485 Interface IC 100Mbps RS485 Hot Swapable 4x Drvrs
Lifecycle:
New from this manufacturer.
Delivery:
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