1
LTC2844
2844f
FEATURES
DESCRIPTIO
U
TYPICAL APPLICATIO
U
3.3V Software-Selectable
Multiprotocol Transceiver
DTE or DCE Multiprotocol Serial Interface with DB-25 Connector
, LTC and LT are registered trademarks of Linear Technology Corporation.
s
Software-Selectable Transceiver Supports:
RS232, RS449, EIA530, EIA530-A, V.35, V.36, X.21
s
Operates from Single 3.3V Supply with LTC2846
s
TUV Rheinland of North America Inc. Certified NET1,
NET2 and TBR2 Compliant,
Report No.: TBR2/051501/02
s
Complete DTE or DCE Port with LTC2846
s
28-Lead SSOP Surface Mount Package
The LTC
2844 is a 4-driver/4-receiver multiprotocol trans-
ceiver. The LTC2844 and LTC2846 form the core of a
complete software-selectable DTE or DCE interface port that
supports the RS232, RS449, EIA530, EIA530-A, V.35, V.36
or X.21 protocols.
The LTC2844 operates from a 3.3V supply and supplies
provided by the LTC2846. The part is available in a 28-lead
SSOP surface mount package.
D2
D1
LTC2844
RTS
DTR
DSR
DCD
CTS
D3
R2
R1
R4
R3
LTC2846
LL
TXD
SCTE
TXC
RXC
RXD
2
14
24
11
15
12
17
9
3
1
4
19
20
6
23
22
5
13
8
10
18
7
16
2844 TA01
D1
SCTE B
SCTE A (113)
TXD B
TXD A (103)
RXC A (115)
RXC B
RXD A (104)
RXD B
RTS A (105)
RTS B
DTR A (108)
DTR B
CTS A (106)
CTS B
LL A (141)
SG (102)
SHIELD (101)
DB-25 CONNECTOR
TXC A (114)
DCD A (107)
DCD B
DSR A (109)
DSR B
D4
D2
D3
R1
R2
R3
TXC B
T
T
T
T
T
APPLICATIO S
U
s
Data Networking
s
CSU and DSU
s
Data Routers
2
LTC2844
2844f
ORDER PART
NUMBER
(Note 1)
Supply Voltage
V
CC
....................................................... 0.3V to 6.5V
V
IN .....................................................................
0.3V to 6.5V
V
EE ......................................................................
10V to 0.3V
V
DD .....................................................................
0.3V to 10V
Input Voltage
Transmitters ............................ 0.3V to (V
CC
+ 0.3V)
Receivers ................................................ 18V to 18V
Logic Pins ............................... 0.3V to (V
CC
+ 0.3V)
Output Voltage
Transmitters .................. (V
EE
0.3V) to (V
DD
+ 0.3V)
Receivers ................................. 0.3V to (V
IN
+ 0.3V)
Short-Circuit Duration
Transmitter Output ...................................... Indefinite
Receiver Output ........................................... Indefinite
V
EE
................................................................... 30 sec
Operating Temperature Range
LTC2844CG ............................................. 0
C to 70
C
LTC2844IG ......................................... 40
C to 85
C
Storage Temperature Range ................. 65
C to 150
C
Lead Temperature (Soldering, 10 sec).................. 300
C
LTC2844CG
LTC2844IG
T
JMAX
= 125
C,
JA
= 90
C/ W,
JC
= 35
C/ W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
The
q
denotes specifications which apply over the full operating tempera-
ture range, otherwise specifications are at T
A
= 25
C. V
CC
= 5V, V
IN
= 3.3V, V
DD
= 8V, V
EE
= 7V for V.28, 5.5V for V.10, V.11
(Notes 2, 3)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Supplies
I
CC
V
CC
Supply Current (DCE Mode,
RS530, RS530-A, X.21 Modes, No Load
2.7
mA
All Digital Pins = GND or V
IN
)
RS530, RS530-A, X.21 Modes, Full Load
q
95
120
mA
V.28 Mode, No Load
q
1
2
mA
V.28 Mode, Full Load
q
1
2
mA
No-Cable Mode
q
600
1200
A
I
EE
V
EE
Supply Current (DCE Mode Unless
RS530, RS530-A, X.21 Modes, No Load
1.6
mA
Otherwise Noted, All Digital Pins = GND or V
IN
) RS530, X.21 Modes, Full Load (DTE Mode)
14
mA
RS530-A, Full Load (DTE Mode)
25
mA
V.28 Mode, No Load
1
mA
V.28 Mode, Full Load
7.5
mA
No-Cable Mode
10
A
I
DD
V
DD
Supply Current (DCE Mode,
RS530, RS530-A, X.21 Modes, No Load
0.2
mA
All Digital Pins = GND or V
IN
)
RS530, RS530-A, X.21 Modes, Full Load
0.2
mA
V.28 Mode, No Load
1
mA
V.28 Mode, Full Load
8
mA
No-Cable Mode
10
A
I
VIN
V
IN
Supply Current (DCE Mode,
All Modes Except No-Cable Mode
490
A
All Digital Pins = GND or V
IN
)
ABSOLUTE AXI U RATI GS
W
W
W
U
PACKAGE/ORDER I FOR ATIO
U
U
W
ELECTRICAL CHARACTERISTICS
1
2
3
4
5
6
7
8
9
10
11
12
13
14
TOP VIEW
28
27
26
25
24
23
22
21
20
19
18
17
16
15
V
CC
V
DD
D1
D2
D3
R1
R2
R3
D4
R4
M0
M1
M2
DCE/DTE
V
EE
GND
D1 A
D1 B
D2 A
D2 B
D3/R1 A
D3/R1 B
R2 A
R2 B
R3 A
R3 B
D4/R4 A
V
IN
R1
D2
D1
R2
D3
G PACKAGE
28-LEAD PLASTIC SSOP
R3
D4
R4
3
LTC2844
2844f
The
q
denotes specifications which apply over the full operating tempera-
ture range, otherwise specifications are at T
A
= 25
C. V
CC
= 5V, V
IN
= 3.3V, V
DD
= 8V, V
EE
= 7V for V.28, 5.5V for V.10, V.11
(Notes 2, 3)
ELECTRICAL CHARACTERISTICS
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
P
D
Internal Power Dissipation (DCE Mode,
RS530, RS530-A, X.21 Modes, Full Load
210
mW
All Digital Pins = GND or V
IN
)
V.28 Mode, Full Load
54
mW
Logic Inputs and Outputs
V
IH
Logic Input High Voltage
q
2
V
V
IL
Logic Input Low Voltage
q
0.8
V
I
IN
Logic Input Current
D1, D2, D3, D4
q
10
A
M0, M1, M2, DCE = GND
q
30
75
120
A
M0, M1, M2, DCE = V
IN
q
10
A
V
OH
Output High Voltage
I
O
= 3mA
q
2.7
3
V
V
OL
Output Low Voltage
I
O
= 1.6mA
q
0.2
0.4
V
I
OSR
Output Short-Circuit Current
0V
V
O
V
IN
q
50
mA
I
OZR
Three-State Output Current
M0 = M1 = M2 = V
IN
, V
O
= 0V
q
30
85
160
A
M0 = M1 = M2 = V
IN
, V
O
= V
IN
q
10
A
V.11 Driver
V
ODO
Open Circuit Differential Output Voltage
R
L
= 1.95k (Figure 1)
q
5
V
V
ODL
Loaded Differential Output Voltage
R
L
= 50
(Figure 1)
0.5V
ODO
0.67V
ODO
V
q
2
V
V
OD
Change in Magnitude of Differential
R
L
= 50
(Figure 1)
q
0.2
V
Output Voltage
V
OC
Common Mode Output Voltage
R
L
= 50
(Figure 1)
q
3
V
V
OC
Change in Magnitude of Common Mode
R
L
= 50
(Figure 1)
q
0.2
V
Output Voltage
I
SS
Short-Circuit Current
V
OUT
= GND
150
mA
I
OZ
Output Leakage Current
0.25V
V
O
0.25V, Power Off or
q
1
100
A
No-Cable Mode or Driver Disabled
t
r
, t
f
Rise or Fall Time
LTC2844C (Figures 2, 5)
q
2
15
25
ns
LTC2844I (Figures 2, 5)
q
2
15
35
ns
t
PLH
Input to Output
LTC2844C (Figures 2, 5)
q
20
40
65
ns
LTC28441 (Figures 2, 5)
q
20
40
75
ns
t
PHL
Input to Output
LTC2844C (Figures 2, 5)
q
20
40
65
ns
LTC2844I (Figures 2, 5)
q
20
40
75
ns
t
Input to Output Difference,
t
PLH
t
PHL
LTC2844C (Figures 2, 5)
q
0
3
12
ns
LTC2844I (Figures 2, 5)
q
0
3
17
ns
t
SKEW
Output to Output Skew
(Figures 2, 5)
3
ns
V.11 Receiver
V
TH
Input Threshold Voltage
7V
V
CM
7V
q
0.2
0.2
V
V
TH
Input Hysteresis
7V
V
CM
7V
q
15
40
mV
I
IN
Input Current (A, B)
10V
V
A,B
10V
q
0.66
mA
R
IN
Input Impedance
10V
V
A,B
10V
q
15
30
k
t
r
, t
f
Rise or Fall Time
(Figures 2, 6)
15
ns
t
PLH
Input to Output
LTC2844C C
L
= 50pF (Figures 2, 6)
q
50
80
ns
LTC2844I C
L
= 50pF (Figures 2, 6)
q
50
90
ns
4
LTC2844
2844f
The
q
denotes specifications which apply over the full operating tempera-
ture range, otherwise specifications are at T
A
= 25
C. V
CC
= 5V, V
IN
= 3.3V, V
DD
= 8V, V
EE
= 7V for V.28, 5.5V for V.10, V.11
(Notes 2, 3)
ELECTRICAL CHARACTERISTICS
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
t
PHL
Input to Output
LTC2844C C
L
= 50pF (Figures 2, 6)
q
50
80
ns
LTC2844I C
L
= 50pF (Figures 2, 6)
q
50
90
ns
t
Input to Output Difference,
t
PLH
t
PHL
LTC2844C C
L
= 50pF (Figures 2, 6)
q
0
4
16
ns
LTC2844I C
L
= 50pF (Figures 2, 6)
q
0
4
21
ns
V.10 Driver
V
O
Output Voltage
Open Circuit, R
L
= 3.9k
q
4
6
V
V
T
Output Voltage
R
L
= 450
(Figure 3)
q
3.6
V
R
L
= 450
(Figure 3)
0.9V
O
I
SS
Short-Circuit Current
V
O
= GND
150
mA
I
OZ
Output Leakage Current
0.25V
V
O
0.25V, Power Off or
q
0.1
100
A
No-Cable Mode or Driver Disabled
t
r
, t
f
Rise or Fall Time
R
L
= 450
, C
L
= 100pF (Figures 3, 7)
2
s
t
PLH
Input to Output
R
L
= 450
, C
L
= 100pF (Figures 3, 7)
1
s
t
PHL
Input to Output
R
L
= 450
, C
L
= 100pF (Figures 3, 7)
1
s
V.10 Receiver
V
TH
Receiver Input Threshold Voltage
q
0.25
0.25
V
V
TH
Receiver Input Hysteresis
q
25
50
mV
I
IN
Receiver Input Current
10V
V
A
10V
q
0.66
mA
R
IN
Receiver Input Impedance
10V
V
A
10V
q
15
30
k
t
r
, t
f
Rise or Fall Time
C
L
= 50pF (Figures 4, 8)
15
ns
t
PLH
Input to Output
C
L
= 50pF (Figures 4, 8)
55
ns
t
PHL
Input to Output
C
L
= 50pF (Figures 4, 8)
109
ns
t
Input to Output Difference,
t
PLH
t
PHL
C
L
= 50pF (Figures 4, 8)
60
ns
V.28 Driver
V
O
Output Voltage
Open Circuit
q
10
V
R
L
= 3k (Figure 3)
q
5
8.5
V
I
SS
Short-Circuit Current
V
O
= GND
q
150
mA
I
OZ
Output Leakage Current
0.25V
V
O
0.25V, Power Off or
q
1
100
A
No-Cable Mode or Driver Disabled
SR
Slew Rate
R
L
= 3k, C
L
= 2500pF (Figures 3, 7)
q
4
30
V/
s
t
PLH
Input to Output
R
L
= 3k, C
L
= 2500pF (Figures 3, 7)
q
1.3
2.5
s
t
PHL
Input to Output
R
L
= 3k, C
L
= 2500pF (Figures 3, 7)
q
1.3
2.5
s
V.28 Receiver
V
THL
Input Low Threshold Voltage
q
0.8
V
V
TLH
Input High Threshold Voltage
q
2
V
V
TH
Receiver Input Hysterisis
q
0.1
0.3
V
R
IN
Receiver Input Impedance
15V
V
A
15V
q
3
5
7
k
t
r
, t
f
Rise or Fall Time
C
L
= 50pF (Figures 4, 8)
15
ns
t
PLH
Input to Output
C
L
= 50pF (Figures 4, 8)
q
60
100
ns
t
PHL
Input to Output
C
L
= 50pF (Figures 4, 8)
q
150
500
ns
5
LTC2844
2844f
DATA RATE (kBd)
I
CC
(mA)
125
120
115
110
105
100
95
90
2844 G01
10
100
1000
10000
DATA RATE (kBd)
10
I
EE
(mA)
26
24
22
20
18
16
14
30
100
2844 G02
20
40 50 60 70 80
10
30
100
20
40 50 60 70 80
DATA RATE (kBd)
I
DD
(mA)
10
9
8
7
6
5
4
2844 G03
TEMPERATURE (
C)
40
I
CC
(mA)
105
100
95
90
85
80
20
60
2844 G04
20
0
40
80
100
40
20
60
20
0
40
80
100
40
20
60
20
0
40
80
100
TEMPERATURE (
C)
I
EE
(mA)
2844 G05
23.5
25.4
25.3
25.2
25.1
25.0
24.9
24.8
24.7
24.6
24.5
TEMPERATURE (
C)
I
DD
(mA)
2844 G06
8.20
8.15
8.10
8.05
8.00
7.95
7.90
7.85
7.80
T
A
= 25
C
T
A
= 25
C
T
A
= 25
C
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: All currents into device pins are positive; all currents out of device
are negative. All voltages are referenced to device ground unless otherwise
specified.
Note 3: All typicals are given for V
CC
= 5V, V
IN
= 3.3V, V
DD
= 8V, V
EE
= 7V
for V.28, 5.5V for V.10, V.11 and T
A
= 25
C.
ELECTRICAL CHARACTERISTICS
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
RS530, X.21 in DCE Mode
(Three V.11 Drivers with Full
Load) I
CC
vs Data Rate
V.28 in DCE Mode
(Three V.28 Drivers with Full
Load) I
DD
vs Data Rate
RS530-A in DTE Mode
(Two V.10 Drivers with Full Load)
I
EE
vs Data Rate
RS530, X.21 in DCE Mode
(Three V.11 Drivers with Full
Load) I
CC
vs Temperature
V.28 in DCE Mode
(Three V.28 Drivers with Full
Load) I
DD
vs Temperature
RS530-A in DTE Mode
(Two V.10 Drivers with Full Load)
I
EE
vs Temperature
6
LTC2844
2844f
U
U
U
PI FU CTIO S
V
CC
(Pin 1): Positive Supply for the Transceivers. Connect
to V
CC
Pin 8 on LTC2846 or to 5V supply. Connect a 1
F
capacitor to ground.
V
DD
(Pin 2): Positive Supply Voltage for V.28. Connect to
V
DD
Pin 7 on LTC2846 or 8V supply. Connect a 1
F
capacitor to ground.
D1 (Pin 3): TTL Level Driver 1 Input.
D2 (Pin 4): TTL Level Driver 2 Input.
D3 (Pin 5): TTL Level Driver 3 Input.
R1 (Pin 6): CMOS Level Receiver 1 Output. Receiver
outputs have a weak pull up to V
IN
when high impedance.
R2 (Pin 7): CMOS Level Receiver 2 Output.
R3 (Pin 8): CMOS Level Receiver 3 Output.
D4 (Pin 9): TTL Level Driver 4 Input.
R4 (Pin 10): CMOS Level Receiver 4 Output.
M0 (Pin 11): TTL Level Mode Select Input 0. Mode select
inputs pull up to V
IN
.
M1 (Pin 12): TTL Level Mode Select Input 1.
M2 (Pin 13): TTL Level Mode Select Input 2.
DCE/DTE (Pin 14): TTL Level Mode Select Input.
V
IN
(Pin 15): Positive Supply for the Receiver Outputs.
3V
V
IN
3.6V. Connect a 1
F capacitor to ground.
D4/R4 A (Pin 16): Receiver 4 Inverting Input and Driver 4
Inverting Output.
R3 B (Pin 17): Receiver 3 Noninverting Input.
R3 A (Pin 18): Receiver 3 Inverting Input.
R2 B (Pin 19): Receiver 2 Noninverting Input.
R2 A (Pin 20): Receiver 2 Inverting Input.
D3/R1 B (Pin 21): Receiver 1 Noninverting Input and
Driver 3 Noninverting Output.
D3/R1 A (Pin 22): Receiver 1 Inverting Input and Driver 3
Inverting Output.
D2 B (Pin 23): Driver 2 Noninverting Output.
D2 A (Pin 24): Driver 2 Inverting Output.
D1 B (Pin 25): Driver 1 Noninverting Output.
D1 A (Pin 26): Driver 1 Inverting Output.
GND (Pin 27): Ground.
V
EE
(Pin 28): Negative Supply Voltage. Connect to V
EE
Pin 31 on LTC2846 or to 7V supply. Connect a 1
F
capacitor to ground.
7
LTC2844
2844f
Figure 3. V.10/V.28 Driver Test Circuit
Figure 4. V.10/V.28 Receiver Test Circuit
A
D
2844 F04
C
L
R
A
A
D
2844 F03
R
L
C
L
TEST CIRCUITS
BLOCK DIAGRA
W
Figure 1. V.11 Driver Test Circuit
A
B
A
R
B
2844 F02
R
L
100
C
L
100pF
C
L
100pF
C
L
A
B
2844 F01
V
OD
V
OC
R
L
R
L
Figure 2. V.11 Driver/Receiver AC Test Circuit
MODE
SELECTION
LOGIC
R2
R2A
R2B
R3
R3A
R3B
S3
20k
20k
20k
20k
S3
10k
6k
D3/R1 B
10k
10k
10k
D3
DCE/DTE
R1
D3
R1
6k
20k
20k
S3
10k
10k
2844 BD
6k
7
8
5
6
20
19
D2
D2A
D2B
D2
4
24
23
D1
D1A
D1B
D1
3
V
DD
2
V
CC
1
GND
27
V
EE
28
26
25
18
17
21
S3
20k
10k
6k
D4/R4 A
D4
R4
D4
9
10
M0 11
M1 12
M2 13
16
V
IN
15
14
R2
R3
R4
D3/R1 A
25
8
LTC2844
2844f
ODE SELECTIO
W
U
(Note 2)
(Note 2)
(Note 2)
(Note 2) (Note 3) (Note 3) (Note 3)
R1
R2
R3
R4A
R1
R2
R4
A
B
A
B
A
B
R3
V.11
V.11
V.11
V.11
V.11
V.11
30k
CMOS
CMOS
Z
V.11
V.11
V.10
30k
V.11
V.11
30k
CMOS
CMOS
Z
V.11
V.11
V.11
V.11
V.11
V.11
30k
CMOS
CMOS
Z
V.11
V.11
V.11
V.11
V.11
V.11
30k
CMOS
CMOS
Z
V.28
30k
V.28
30k
V.28
30k
30k
CMOS
CMOS
Z
V.11
V.11
V.11
V.11
V.11
V.11
30k
CMOS
CMOS
Z
V.28
30k
V.28
30k
V.28
30k
30k
CMOS
CMOS
Z
30k
30k
30k
30k
30k
30k
30k
Z
Z
Z
30k
30k
V.11
V.11
V.11
V.11
V.10
Z
CMOS
CMOS
30k
30k
V.10
30k
V.11
V.11
V.10
Z
CMOS
CMOS
30k
30k
V.11
V.11
V.11
V.11
V.10
Z
CMOS
CMOS
30k
30k
V.11
V.11
V.11
V.11
V.10
Z
CMOS
CMOS
30k
30k
V.28
30k
V.28
30k
V.28
Z
CMOS
CMOS
30k
30k
V.11
V.11
V.11
V.11
V.10
Z
CMOS
CMOS
30k
30k
V.28
30k
V.28
30k
V.28
Z
CMOS
CMOS
30k
30k
30k
30k
30k
30k
30k
Z
Z
Z
(Note 1) (Note 1) (Note 1)
MODE NAME
M2
M1
M0
DCE
D1
D3
D4
D1
D2
D3
D4A
/DTE
D2
A
B
A
B
A
B
Not Used
(Default V.11)
0
0
0
0
TTL
X
TTL
V.11
V.11
V.11
V.11
Z
Z
V.10
RS530A
0
0
1
0
TTL
X
TTL
V.11
V.11
V.10
Z
Z
Z
V.10
RS530
0
1
0
0
TTL
X
TTL
V.11
V.11
V.11
V.11
Z
Z
V.10
X.21
0
1
1
0
TTL
X
TTL
V.11
V.11
V.11
V.11
Z
Z
V.10
V.35
1
0
0
0
TTL
X
TTL
V.28
Z
V.28
Z
Z
Z
V.28
RS449/V.36
1
0
1
0
TTL
X
TTL
V.11
V.11
V.11
V.11
Z
Z
V.10
V.28/RS232
1
1
0
0
TTL
X
TTL
V.28
Z
V.28
Z
Z
Z
V.28
No Cable
1
1
1
0
X
X
X
Z
Z
Z
Z
Z
Z
Z
Not Used
(Default V.11)
0
0
0
1
TTL
TTL
X
V.11
V.11
V.11
V.11
V.11
V.11
Z
RS530A
0
0
1
1
TTL
TTL
X
V.11
V.11
V.10
Z
V.11
V.11
Z
RS530
0
1
0
1
TTL
TTL
X
V.11
V.11
V.11
V.11
V.11
V.11
Z
X.21
0
1
1
1
TTL
TTL
X
V.11
V.11
V.11
V.11
V.11
V.11
Z
V.35
1
0
0
1
TTL
TTL
X
V.28
Z
V.28
Z
V.28
Z
Z
RS449/V.36
1
0
1
1
TTL
TTL
X
V.11
V.11
V.11
V.11
V.11
V.11
Z
V.28/RS232
1
1
0
1
TTL
TTL
X
V.28
Z
V.28
Z
V.28
Z
Z
No Cable
1
1
1
1
X
X
X
Z
Z
Z
Z
Z
Z
Z
MODE NAME
M2
M1
M0
DCE
/DTE
Not Used
(Default V.11)
0
0
0
0
RS530A
0
0
1
0
RS530
0
1
0
0
X.21
0
1
1
0
V.35
1
0
0
0
RS449/V.36
1
0
1
0
V.28/RS232
1
1
0
0
No Cable
1
1
1
0
Not Used
(Default V.11)
0
0
0
1
RS530A
0
0
1
1
RS530
0
1
0
1
X.21
0
1
1
1
V.35
1
0
0
1
RS449/V.36
1
0
1
1
V.28/RS232
1
1
0
1
No Cable
1
1
1
1
Note 1: Driver inputs are TTL level compatible.
Note 2: Unused receiver inputs are terminated with 30k to ground.
Note 3: Receiver outputs are CMOS level compatible and have a weak pull-up to V
IN
when Z.
9
LTC2844
2844f
Figure 7. V.10, V.28 Driver Propagation Delays
Figure 6. V.11, V.35 Receiver Propagation Delays
Figure 8. V.10, V.28 Receiver Propagation Delays
3V
0V
1.5V
0V
3V
3V
1.5V
0V
3V
3V
t
PHL
t
f
V
O
V
O
D
A
t
PLH
t
r
2844 F07
V
OD2
V
OD2
0V
1.65V
0V
1.65V
t
PLH
V
OH
V
OL
B A
R
t
PHL
2844 F06
f = 1MHz : t
r
10ns : t
f
10ns
INPUT
OUTPUT
V
IH
V
IL
RECEIVER THRESHOLD
1.65V
RECEIVER THRESHOLD
t
PHL
V
OH
V
OL
A
R
t
PLH
2844 F08
1.65V
3V
1.5V
1.5V
50%
10%
90%
t
PLH
t
r
0V
V
O
V
O
V
O
D
B A
A
B
t
PHL
t
SKEW
t
SKEW
2844 F05
1/2 V
O
f = 1MHz : t
r
10ns : t
f
10ns
V
DIFF
= V(A) V(B)
50%
10%
90%
t
f
Figure 5. V.11, V.35 Driver Propagation Delays
SWITCHI G TI E WAVEFOR S
U
W
W
10
LTC2844
2844f
Overview
The LTC2846/LTC2844 form the core of a complete soft-
ware-selectable DTE or DCE interface port that supports
the RS232, RS449, EIA530, EIA530-A, V.35, V.36 or X.21
protocols.
A complete DCE-to-DTE interface operating in EIA530
mode is shown in Figure 9. The LTC2846 of each port is
used to generate the clock and data signals. The LTC2844
is used to generate the control signals along with LL (local
loop-back). Cable termination is used only for the clock
and data signals. The control signals do not need any
external resistors.
Figure 9. Complete Multiprotocol Interface in EIA530 Mode
APPLICATIO
N
S I
N
FOR
M
ATIO
N
W
U
U
U
LTC2846
DCE
DTE
LTC2846
D3
R1
103
103
103
R3
TXD
SCTE
TXC
RXC
RXD
103
R2
103
R3
R1
D2
D1
R2
D3
2844 F09
LTC2844
D4
R1
R2
R3
LL
TXC
RXC
RXD
SERIAL
CONTROLLER
SCTE
TXD
LTC2844
TXD
SCTE
TXC
RXC
RXD
RTS
DTR
DCD
DSR
CTS
LL
RTS
DTR
DCD
DSR
CTS
RTS
DTR
DCD
DSR
CTS
LL
SERIAL
CONTROLLER
R4
R4
D3
D2
D1
R2
R1
R3
D2
D1
D4
D3
D2
D1
11
LTC2844
2844f
Mode Selection
The interface protocol is selected using the mode select
pins M0, M1 and M2 (see the Mode Selection table).
For example, if the port is configured as a V.35 interface,
the mode selection pins should be M2 = 1, M1 = 0, M0 = 0.
For the control signals, the drivers and receivers will
operate in V.28 (RS232) electrical mode. For the clock and
data signals, the drivers and receivers will operate in V.35
electrical mode. The DCE/DTE pin will configure the port
for DCE mode when high, and DTE when low.
The interface protocol may be selected simply by plug-
ging the appropriate interface cable into the connector.
The mode pins are routed to the connector and are left
unconnected (1) or wired to ground (0) in the cable as
shown in Figure 10.
The internal pull-up current sources will ensure a binary 1
when a pin is left unconnected and that the LTC2846/
LTC2844 enter the no-cable mode when the cable is
removed. In the no-cable mode the LTC2846/LTC2844
supply current drops to less than 900
A and all driver
outputs are forced into a high impedance state.
The mode selection may also be accomplished by using
jumpers to connect the mode pins to ground or V
IN
.
Figure 10. Single Port DCE V.35 Mode Selection in the Cable
APPLICATIO
N
S I
N
FOR
M
ATIO
N
W
U
U
U
NC
NC
CABLE
2844 F10
15
16
18
19
LTC2846
LTC2844
CONNECTOR
14
13
12
11
(DATA)
M0
M1
M2
DCE/DTE
DCE/DTE
M2
M1
M0
(DATA)
12
LTC2844
2844f
Cable Termination
Traditional implementations have included switching
resistors with expensive relays, or required the user to
change termination modules every time the interface
standard has changed. Custom cables have been used
with the termination in the cable head or separate termina-
tions are built on the board and a custom cable routes the
signals to the appropriate termination. Switching the
termination with FETs is difficult because the FETs must
remain off even though the signal voltage is beyond the
supply voltage for the FET drivers or the power is off.
Using the LTC2846/LTC2844 solves the cable termination
switching problem. Via software control, appropriate ter-
mination for the V.10 (RS423), V.11 (RS422), V.28 (RS232)
and V.35 electrical protocols is chosen.
V.10 (RS423) Interface
A typical V.10 unbalanced interface is shown in Figure 11.
A V.10 single-ended generator output A with ground C is
connected to a differential receiver with inputs A
'
con-
nected to A, and input C
'
connected to the signal return
ground C. Usually, no cable termination is required for
V.10 interfaces, but the receiver inputs must be compliant
with the impedance curve shown in Figure 12.
The V.10 receiver configuration in the LTC2844 is shown
in Figure 13. In V.10 mode switch S3 inside the LTC2844
is turned off.The noninverting input is disconnected inside
the LTC2844 receiver and connected to ground. The cable
termination is then the 30k input impedance to ground of
the LTC2844 V.10 receiver.
I
Z
V
Z
10V
3.25mA
3.25mA
3V
3V
10V
2844 F12
Figure 12. V.10 Receiver Input Impedance
Figure 11. Typical V.10 Interface
Figure 13. V.10 Receiver Configuration
A
A
'
C
C
'
GENERATOR
BALANCED
INTERCONNECTING
CABLE
LOAD
CABLE
TERMINATION
RECEIVER
2844 F11
R5
20k
LTC2844
RECEIVER
2844 F13
A
'
B
'
C
'
R8
6k
S3
R6
10k
R7
10k
GND
R4
20k
APPLICATIO
N
S I
N
FOR
M
ATIO
N
W
U
U
U
13
LTC2844
2844f
V.11 (RS422) Interface
A typical V.11 balanced interface is shown in Figure 14. A
V.11 differential generator with outputs A and B with
ground C is connected to a differential receiver with
ground C
'
, inputs A
'
connected to A, B
'
connected to B. The
V.11 interface has a differential termination at the receiver
end that has a minimum value of 100
. The termination
resistor is optional in the V.11 specification, but for the
high speed clock and data lines, the termination is required
to prevent reflections from corrupting the data. The
receiver inputs must also be compliant with the imped-
ance curve shown in Figure 12.
In V.11 mode, all switches are off except S1 of the
LTC2846's receivers which connects a 103
differential
termination impedance to the cable as shown in Figure
15
1
. The LTC2844 only handles control signals, so no
termination other than its V.11 receivers' 30k input imped-
ance is necessary.
Figure 15. V.11 Receiver Configuration
A
A
'
B
C
B
'
C
'
GENERATOR
BALANCED
INTERCONNECTING
CABLE
LOAD
CABLE
TERMINATION
RECEIVER
100
MIN
2844 F14
V.28 (RS232) Interface
A typical V.28 unbalanced interface is shown in Figure 16.
A V.28 single-ended generator output A with ground C is
connected to a single-ended receiver with input A
'
con-
nected to A, ground C
'
connected via the signal return
ground C.
In V.28 mode all switches are off except S3 inside the
LTC2846/LTC2844 which connects a 6k (R8) impedance
to ground in parallel with 20k (R5) plus 10k (R6) for a
combined impedance of 5k as shown in Figure 17. The
noninverting input is disconnected inside the LTC2846/
LTC2844 receiver and connected to a TTL level reference
voltage for a 1.4V receiver trip point.
A
A
'
C
C
'
GENERATOR
BALANCED
INTERCONNECTING
CABLE
LOAD
CABLE
TERMINATION
RECEIVER
2844 F16
Figure 14. Typical V.11 Interface
R5
20k
LTC2844
RECEIVER
2844 F17
A
'
B
'
C
'
R8
6k
S3
R6
10k
R7
10k
GND
R4
20k
Figure 17. V.28 Receiver Configuration
Figure 16. Typical V.28 Interface
APPLICATIO
N
S I
N
FOR
M
ATIO
N
W
U
U
U
1
Actually, there is no switch S1 in receivers R2 and R3. However, for simplicity, all termination
networks on the LTC2846 can be treated identically if it is assumed that an S1 switch exists and is
always closed on the R2 and R3 receivers.
R3
124
R5
20k
LTC2846
RECEIVER
2844 F15
A
'
B
'
C
'
R1
51.5
R8
6k
S2
S3
R2
51.5
R6
10k
R7
10k
GND
R4
20k
S1
14
LTC2844
2844f
A
A
'
B
C
B
'
C
'
GENERATOR
BALANCED
INTERCONNECTING
CABLE
LOAD
CABLE
TERMINATION
RECEIVER
2844 F18
50
125
50
50
125
50
Figure 18. Typical V.35 Interface
Figure 19. V.35 Receiver Configuration
V.35 Interface
A typical V.35 balanced interface is shown in Figure 18. A
V.35 differential generator with outputs A and B with
ground C is connected to a differential receiver with
ground C
'
, inputs A
'
connected to A, B
'
connected to B. The
V.35 interface requires a T or delta network termination at
the receiver end and the generator end. The receiver
differential impedance measured at the connector must be
100
10
, and the impedance between shorted termi-
nals (A
'
and B
'
)
and ground C
'
must be 150
15
.
In V.35 mode, both switches S1 and S2 inside the LTC2846
are on, connecting the T network impedance as shown in
Figure 19. The 30k input impedance of the receiver is
placed in parallel with the T network termination, but does
not affect the overall input impedance significantly.
The generator differential impedance must be 50
to
150
and the impedance between shorted terminals (A
and B) and ground C must be 150
15
. For the
generator termination, switches S1 and S2 are both on as
shown in Figure 20.
No-Cable Mode
The no-cable mode (M0 = M1 = M2 = 1) is intended for the
case when the cable is disconnected from the connector.
The bias circuitry, drivers and receivers are turned off, the
driver outputs are forced into a high impedance state, and
the supply current drops to less than 600
A.
LTC2846 Supplies
The LTC2846 uses an internal capacitive charge pump to
generate V
DD
and V
EE
as shown in Figure 21. A voltage
doubler generates about 8V on V
DD
and a voltage inverter
generates about 7.5V for V
EE
. Three 1
F surface mounted
tantalum or ceramic capacitors are required for C1, C2 and
C3. The V
EE
capacitor C4 should be a minimum of 3.3
F.
All capacitors are 16V and should be placed as close as
possible to the LTC2846 to reduce EMI.
The LTC2846 has an internal boost switching regulator
which generates a 5V output from the 3.3V supply as
shown in Figure 22. The 5V V
CC
supplies its internal charge
pump and transceivers as well as its companion chip.
APPLICATIO
N
S I
N
FOR
M
ATIO
N
W
U
U
U
Figure 20. V.35 Driver
V.35 DRIVER
A
B
C
51.5
S2
S1
2844 F20
51.5
LTC2846
124
R3
124
R5
20k
LTC2846
RECEIVER
2844 F19
A
'
B
'
C
'
R1
51.5
R8
6k
S2
S3
R2
51.5
R6
10k
R7
10k
GND
R4
20k
S1
33
32
31
30
2844 F21
7
6
5
8
C3
1
F
C5
10
F
5V
C1
1
F
C2
1
F
C4
3.3
F
LTC2846
V
DD
C1
+
C1
V
CC
C2
+
C2
V
EE
GND
+
Figure 21. Charge Pump
15
LTC2844
2844f
mode, the TXD signal is routed to Pins 2 and 14 via Driver 1
in the LTC2846. In DCE mode, Driver 1 now routes the RXD
signal to Pins 2 and 14.
Multiprotocol Interface with RL, LL, TM and a DB-25
Connector
If the RL, LL and TM signals are implemented, there are not
enough drivers and receivers available in the LTC2846/
LTC2844. In Figure 25, the required control signals are
handled by the LTC2845. The LTC2845 has an additional
single-ended driver/receiver pair that can handle two more
optional control signals such as TM and LL.
Cable-Selectable Multiprotocol Interface
A cable-selectable multiprotocol DTE/DCE interface is
shown in Figure 26. The select lines M0, M1 and DCE/DTE
are brought out to the connector. The mode is selected by
the cable by wiring M0 (connector Pin 18) and M1 (con-
nector Pin 21) and DCE/DTE (connector Pin 25) to ground
(connector Pin 7) or letting them float. If M0, M1 or DCE/
DTE is floating, internal pull-up current sources will pull
the signals to V
IN
. The select bit M2 is floating and
therefore, internally pulled high. When the cable is pulled
out, the interface will go into the no-cable mode.
Compliance Testing
The LTC2846/LTC2844 chipset has been tested by TUV
Rheinland of North America Inc. and passed the NET1,
NET2 and TBR2 requirements. Copies of the test report are
available from LTC or TUV Rheinland of North America Inc.
The title of the report is Test Report No. TBR2/051501/02
The address of TUV Rheinland of North America Inc. is:
Receiver Fail-Safe
All LTC2846/LTC2844 receivers feature fail-safe opera-
tion in all modes. If the receiver inputs are left floating or
shorted together by a termination resistor, the receiver
output will always be forced to a logic high.
DTE vs DCE Operation
The DCE/DTE pin acts as an enable for Driver 3/Receiver 1
in the LTC2846, and Driver 3/Receiver 1 and Receiver 4/
Driver 4 in the LTC2844.
The LTC2846/LTC2844 can be configured for either DTE
or DCE operation in one of two ways: a dedicated DTE or
DCE port with a connector of appropriate gender or a port
with one connector that can be configured for DTE or DCE
operation by rerouting the signals to the LTC2846/LTC2844
using a dedicated DTE cable or dedicated DCE cable.
A dedicated DTE port using a DB-25 male connector is
shown in Figure 23. The interface mode is selected by logic
outputs from the controller or from jumpers to either V
IN
or GND on the mode select pins.
A port with one DB-25 connector, but can be configured
for either DTE or DCE operation is shown in Figure 24. The
configuration requires separate cables for proper signal
routing in DTE or DCE operation. For example, in DTE
APPLICATIO
N
S I
N
FOR
M
ATIO
N
W
U
U
U
Figure 22. Boost Switching Regulator
GND
V
IN
SW
SHDN
FB
V
IN
3.3V
4
35
2844 F22
D1
L1
5.6
H
2, 34
R1
13k
BOOST
SWITCHING
REGULATOR
C5
10
F
C6
10
F
R2
4.3k
V
CC
5V
480mA
C1,C2: TAIYO YUDEN X5R JMK316BJ106ML
D1: ON SEMICONDUCTOR MBR0520
L1: SUMIDA CR43-5R6
SHDN
3
36
TUV Rheinland of North America Inc.
1775, Old Highway 8 NW, Suite 107
St. Paul, MN 55112
Tel. (651) 639-0775
Fax (651) 639-0873
16
LTC2844
2844f
Figure 23. Controller-Selectable Multiprotocol DTE Port with DB-25 Connector
TYPICAL APPLICATIO S
U
D2
D1
LTC2844
RTS
DTR
DSR
DCD
CTS
D3
R2
R1
R4
R3
LTC2846
LL
TXD
SCTE
TXC
RXC
RXD
M0
M1
M2
DCE/DTE
V
CC
V
DD
V
EE
GND
2
14
24
11
15
12
17
9
3
1
4
19
20
8
23
10
6
22
5
13
18
7
16
2844 F23
C2
1
F
R1
13k
C1
1
F
C6
10
F
C3
1
F
C4
3.3
F
SCTE B
RTS A (105)
RTS B
DTR A (108)
DTR B
CTS A (106)
CTS B
LL A (141)
SG
SHIELD
DB-25 MALE
CONNECTOR
DCD A (109)
DCD B
DSR A (107)
DSR B
D4
V
CC
5V
SHDN
V
IN
3.3V
CHARGE
PUMP
BOOST
SWITCHING
REGULATOR
L1
5.6
H
+
33
7
35
4
36
D1
MBR0520
3
5
6
8
9
10
11
12
13
14
15
16
18
19
1
2
3
4
5
6
7
8
10
9
V
IN
15
V
IN
3.3V
16
17
18
19
20
21
22
23
24
25
32
31
30
29
28
27
26
25
24
23
22
21
20
17 V
IN
3.3V
26
27
28
C5
10
F
C9
1
F
C7
1
F
C8
1
F
M0
M1
M2
DCE/DTE
M0
M1
M2
11
12
13
14
D1
D2
D3
R1
R2
R3
TXD A (103)
TXD B
TXC A (114)
RXC A (115)
RXD A (104)
TXC B
RXC B
RXD B
SCTE A (113)
T
T
T
T
T
C10
1
F
R2
4.3k
V
CC
5V
17
LTC2844
2844f
Figure 24. Controller-Selectable Multiprotocol DTE/DCE Port with DB-25 Connector
TYPICAL APPLICATIO S
U
D2
D1
LTC2844
D3
R2
R1
R4
R3
LTC2846
M0
M1
M2
DCE/DTE
V
CC
V
DD
V
EE
GND
2844 F25
C2
1
F
R1
13k
C1
1
F
C6
10
F
C3
1
F
C4
3.3
F
D4
V
CC
5V
SHDN
V
IN
3.3V
CHARGE
PUMP
BOOST
SWITCHING
REGULATOR
L1
5.6
H
+
33
7
35
4
36
D1
MBR0520
3
5
6
8
9
10
11
12
13
14
15
16
18
19
1
2
3
4
5
6
7
8
10
9
DCE/DTE
V
IN
15
V
IN
3.3V
16
17
18
19
20
21
22
23
24
25
32
31
30
29
28
27
26
25
24
23
22
21
20
26
27
28
C5
10
F
C9
1
F
C7
1
F
C8
1
F
M0
M1
M2
DCE/DTE
M0
M1
M2
11
12
13
14
D1
D2
D3
R1
R2
R3
T
T
T
T
T
C10
1
F
R2
4.3k
V
CC
5V
DTE_TXD/DCE_RXD
DTE_SCTE/DCE_RXC
DTE_TXC/DCE_TXC
DTE_RXC/DCE_SCTE
DTE_RXD/DCE_TXD
DTE_RTS/DCE_CTS
DTE_DTR/DCE_DSR
DTE_DCD/DCE_DCD
DTE_DSR/DCE_DTR
DTE_CTS/DCE_RTS
DTE_LL/DCE_LL
2
14
24
11
15
12
17
9
3
1
4
19
20
8
23
10
6
22
5
13
18
7
16
SCTE B
RTS A
RTS B
DTR A
DTR B
CTS A
CTS B
DSR A
DSR B
CTS A
CTS B
LL A
SG
SHIELD
DB-25
CONNECTOR
DCD A
DCD B
DSR A
DSR B
RTS A
RTS B
LL A
DCD A
DCD B
DTR A
DTR B
TXD A
TXD B
TXC A
RXC A
RXD A
TXC B
RXC B
RXD B
TXC A
SCTE A
TXD A
TXC B
SCTE B
TXD B
SCTE A
RXC B
RXD A
DTE
DCE
RXD B
RXC A
17 V
IN
3.3V
18
LTC2844
2844f
Figure 25. Controller-Selectable Multiprotocol DTE/DCE Port with RL, LL, TM and DB-25 Connector
TYPICAL APPLICATIO S
U
D2
D1
LTC2845
DTE_RTS/DCE_CTS
DTE_DTR/DCE_DSR
DTE_DSR/DCE_DTR
DTE_DCD/DCE_DCD
DTE_CTS/DCE_RTS
D3
R2
R1
R4
R3
LTC2846
DTE_LL/DCE_RI
DTE_RI/DCE_LL
DTE_TM/DCE_RL
DTE_RL/DCE_TM
DTE_TXD/DCE_RXD
DTE_SCTE/DCE_RXC
DTE_TXC/DCE_TXC
DTE_RXC/DCE_SCTE
DTE_RXD/DCE_TXD
M0
M1
M2
DCE/DTE
V
CC
V
DD
V
EE
GND
2844 F26
C2
1
F
R1
13k
C1
1
F
C6
10
F
C3
1
F
C4
3.3
F
D4
V
CC
5V
SHDN
V
IN
3.3V
CHARGE
PUMP
BOOST
SWITCHING
REGULATOR
L1
5.6
H
+
33
7
35
4
36
D1
MBR0520
3
5
6
8
9
10
11
12
13
14
15
16
18
19
1, 19
2
3
4
5
6
7
8
10
9
D5
18
DCE/DTE
V
IN
D4ENB
R4EN
20
15
16
NC
V
IN
3.3V
23
R5
17
22
21
25
24
26
27
28
29
30
31
32
33
32
31
30
29
28
27
26
25
24
23
22
21
20
34
35
36
C5
10
F
C9
1
F
C7
1
F
C8
1
F
M0
M1
M2
DCE/DTE
M0
M1
M2
11
12
13
14
D1
D2
D3
R1
R2
R3
T
T
T
T
T
C10
1
F
R2
4.3k
V
CC
5V
18
*
*OPTIONAL
21
25
LL
LL
RL
RL
TM
TM
RI
RI
2
14
24
11
15
12
17
9
3
1
4
19
20
8
23
10
6
22
5
13
7
16
TXD A
TXD B
SCTE A
SCTE B
RXD A
RXD B
RXC A
RXC B
RXC A
RXC B
RXD A
RXD B
RTS A
RTS B
DTR A
DTR B
CTS A
CTS B
DSR A
DSR B
CTS A
CTS B
SG
SHIELD
DB-25
CONNECTOR
TXC A
TXC B
SCTE A
SCTE B
TXD A
TXD B
TXC A
TXC B
DCD A
DCD B
DSR A
DSR B
RTS A
RTS B
DCD A
DCD B
DTR A
DTR B
DTE
DCE
17 V
IN
3.3V
19
LTC2844
2844f
Figure 26. Cable-Selectable Multiprotocol DTE/DCE Port with DB-25 Connector
TYPICAL APPLICATIO S
U
D2
D1
LTC2844
DTE_RTS/DCE_CTS
DTE_DTR/DCE_DSR
DTE_DSR/DCE_DTR
DTE_DCD/DCE_DCD
DTE_CTS/DCE_RTS
D3
R2
R1
R4
R3
LTC2846
DTE_TXD/DCE_RXD
DTE_SCTE/DCE_RXC
DTE_TXC/DCE_TXC
DTE_RXC/DCE_SCTE
DTE_RXD/DCE_TXD
M0
M1
M2
DCE/DTE
V
CC
V
DD
V
EE
GND
2844 F27
C2
1
F
R1
13k
C1
1
F
C6
10
F
C3
1
F
C4
3.3
F
D4
V
CC
5V
SHDN
V
IN
3.3V
CHARGE
PUMP
BOOST
SWITCHING
REGULATOR
L1
5.6
H
+
33
7
35
4
36
D1
MBR0520
3
5
6
8
9
10
11
12
13
14
15
16
18
19
NC
1
2
3
4
5
6
7
8
10
9
NC
V
IN
15
V
IN
3.3V
16
17
18
19
20
21
22
23
24
25
32
31
30
29
28
27
26
25
24
23
22
21
20
26
27
28
C5
10
F
C9
1
F
C7
1
F
C8
1
F
M0
M1
M2
DCE/DTE
11
12
13
14
D1
D2
D3
R1
R2
R3
T
T
T
T
T
C10
1
F
R2
4.3k
V
CC
5V
2
14
24
11
15
12
17
9
3
1
25
21
18
4
19
20
8
23
10
6
22
5
13
7
16
RXD A
RXD B
RXC A
RXC B
RXC A
RXC B
RXD A
RXD B
RTS A
RTS B
DTR A
DTR B
CTS A
CTS B
DSR A
DSR B
CTS A
CTS B
SG
SHIELD
DCE/DTE
M1
M0
DB-25
CONNECTOR
TXC A
TXC B
SCTE A
SCTE B
TXD A
TXD B
TXC A
TXC B
DCD A
DCD B
DSR A
DSR B
RTS A
RTS B
DCD A
DCD B
DTR A
DTR B
DTE
DCE
MODE
V.35
RS449, V.36
RS232
PIN 18
PIN 7
NC
PIN 7
PIN 21
PIN 7
PIN 7
NC
CABLE WIRING FOR MODE SELECTION
MODE
PIN 25
DTE
PIN 7
DCE
NC
CABLE WIRING FOR
DTE/DCE SELECTION
TXD A
TXD B
SCTE A
SCTE B
17 V
IN
3.3V
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
20
LTC2844
2844f
LT/TP 0503 1K PRINTED IN USA
LINEAR TECHNOLOGY CORPORATION 2002
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC1321
Dual RS232/RS485 Transceiver
Two RS232 Driver/Receiver Pairs or Two RS485 Driver/Receiver Pairs
LTC1334
Single 5V RS232/RS485 Multiprotocol Transceiver
Two RS232 Driver/Receiver or Four RS232 Driver/Receiver Pairs
LTC1343
Software-Selectable Multiprotocol Transceiver
4-Driver/4-Receiver for Data and Clock Signals
LTC1344A
Software-Selectable Cable Terminator
Perfect for Terminating the LTC1543 (Not Needed with LTC1546)
LTC1345
Single Supply V.35 Transceiver
3-Driver/3-Receiver for Data and Clock Signals
LTC1346A
Dual Supply V.35 Transceiver
3-Driver/3-Receiver for Data and Clock Signals
LTC1543
Software-Selectable Multiprotocol Transceiver
Terminated with LTC1344A for Data and Clock Signals, Companion to
LTC1544 or LTC1545 for Control Signals
LTC1544
Software-Selectable Multiprotocol Transceiver
Companion to LTC1546 or LTC1543 for Control Signals Including LL
LTC1545
Software-Selectable Multiprotocol Transceiver
5-Driver/5-Receiver Companion to LTC1546 or LTC1543
for Control Signals Including LL, TM and RL
LTC1546
Software-Selectable Multiprotocol Transceiver
3-Driver/3-Receiver with Termination for Data and Clock Signals
LTC2845
3.3V Software-Selectable Multiprotocol Transceiver
3.3V Supply, 5-Driver/5-Receiver Companion to LTC2846 for Control
Signals Including LL, TM and RL
LTC2846
3.3V Software-Selectable Multiprotocol Transceiver
3.3V Supply, 3-Driver/3-Receiver with Termination for Data and Clock
Signals, Generates the Required 5V and
8V Supplies for LTC2846 and
Companion Parts
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
q
FAX: (408) 434-0507
q
www.linear.com
U
PACKAGE DESCRIPTIO
G Package
28-Lead Plastic SSOP (5.3mm)
(Reference LTC DWG # 05-08-1640)
G28 SSOP 0802
0.09 0.25
(.0035 .010)
0
8
0.55 0.95
(.022 .037)
5.00 5.60**
(.197 .221)
7.40 8.20
(.291 .323)
1
2 3
4
5
6 7 8
9 10 11 12
14
13
9.90 10.50*
(.390 .413)
25
26
22 21 20 19 18 17 16 15
23
24
27
28
2.0
(.079)
0.05
(.002)
0.65
(.0256)
BSC
0.22 0.38
(.009 .015)
MILLIMETERS
(INCHES)
DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED .152mm (.006") PER SIDE
DIMENSIONS DO NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED .254mm (.010") PER SIDE
*
**
NOTE:
1. CONTROLLING DIMENSION: MILLIMETERS
2. DIMENSIONS ARE IN
3. DRAWING NOT TO SCALE
0.42
0.03
0.65 BSC
5.3 5.7
7.8 8.2
RECOMMENDED SOLDER PAD LAYOUT
1.25
0.12
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