LTC2845CG#PBF [Linear]
LTC2845 - 3.3V Software-Selectable Mutiprotocol Transceiver; Package: SSOP; Pins: 36; Temperature Range: 0°C to 70°C;
| 型号： | LTC2845CG#PBF |
| 厂家： | 
Linear |
| 描述： | LTC2845 - 3.3V Software-Selectable Mutiprotocol Transceiver; Package: SSOP; Pins: 36; Temperature Range: 0°C to 70°C 驱动 光电二极管 接口集成电路 驱动器 |
| 文件： | 总20页 (文件大小：278K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC2845
3.3V Software-Selectable
Multiprotocol Transceiver
U
FEATURES
DESCRIPTIO
The LTC®2845 is a 5-driver/5-receiver multiprotocol trans-
ceiver. The LTC2845 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.
■
Software-Selectable Transceiver Supports:
RS232, RS449, EIA530, EIA530-A, V.35, V.36, X.21
■
Operates from Single 3.3V Supply with LTC2846 or
a Single 5V Supply with 3.3V Logic with LTC2847
TUV Rheinland of North America Inc. Certified NET1,
■
NET2 and TBR2 Compliant,
Report No.: TBR2/050101/02
The LTC2845 operates from a 3.3V supply and supplies
provided by the LTC2846. This part is available in a 36-lead
SSOPand38-lead(7mmx5mm)QFNpackage.TheLTC2845
andLTC2847inQFNpackagesofferthesmallestmultiprotocol
serial port available.
■
Complete DTE or DCE Port with LTC2846 or LTC2847
■
Available in a 36-Lead Narrow (0.209") SSOP and
38-Lead (7mm x U5mm) QFN package
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
■
Data Networking
■
CSU and DSU
■
Data Routers
U
TYPICAL APPLICATIO
DTE or DCE Multiprotocol Serial Interface with DB-25 Connector
RL TM
RI
LL CTS
DSR
DCD
DTR
RTS
TXC
SCTE
TXD
RXD
RXC
LTC2846
LTC2845
D3
D2
D1
D3
D2
T
D1
T
D5
R5
D4
R3
R2
R1
R4
R3
T
R2
T
R1
T
21
25
*
18 13
5
22
6
10
8
23 20 19
4
1
7
16
3
9
17
12
15 11
24 14
2
*OPTIONAL
DB-25 CONNECTOR
2845 TA01
sn2845 2845fs
1
LTC2845
W W U W
(Note 1)
ABSOLUTE MAXIMUM RATINGS
Supply Voltage
Short-Circuit Duration
VCC ....................................................... –0.3V to 6.5V
VIN ..................................................................... –0.3V to 6.5V
VEE ...................................................................... –10V to 0.3V
VDD ..................................................................... –0.3V to 10V
Input Voltage
Transmitter Output ..................................... Indefinite
Receiver Output.......................................... Indefinite
VEE.................................................................. 30 sec
Operating Temperature Range
LTC2845C ............................................... 0°C to 70°C
LTC2845I........................................... –40°C to 85°C
Storage Temperature Range ................ –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
Transmitters ........................... –0.3V to (VCC + 0.3V)
Receivers............................................... –18V to 18V
Logic Pins .............................. –0.3V to (VCC + 0.3V)
Output Voltage
Transmitters .................. (VEE – 0.3V) to (VDD + 0.3V)
Receivers................................. –0.3V to (VIN + 0.3V)
U
W U
PACKAGE/ORDER INFORMATION
TOP VIEW
TOP VIEW
ORDER PART
NUMBER
ORDER PART
NUMBER
V
V
1
2
36 V
EE
CC
38 37 36 35 34 33 32
35 GND
34 D1 A
33 D1 B
32 D2 A
31 D2 B
30 D3/R1 A
29 D3/R1 B
28 R2 A
27 R2 B
26 R3 A
25 R3 B
24 D4 A
23 R4 A
22 R5 A
21 D5 A
DD
D1
D2
D3
R1
R2
R3
D4
R4
M0
M1
1
2
3
4
5
6
7
8
9
31 D1 B
30 D2 A
3
D1
D2
D3
LTC2845CUHF
LTC2845IUHF
LTC2845CG
LTC2845IG
D2
D3
4
D2 B
29
28
5
D3/R1 A
R1
6
27 D3/R1 B
R2 A
R2
7
R3
8
26
39
D4
9
25 R2 B
24 R3 A
23 R3 B
22 D4 A
21 R4 A
R1
R4
10
11
12
13
14
15
16
17
18
R2
R3
M0
M1
UHF PART
MARKING
M2 10
NC 11
M2
D4
D5
DCE/DTE
D4ENB
R4EN
R5
20
DCE/DTE 12
R5 A
R4
R5
13 14 15 16 17 18 19
UHF PACKAGE
2845
2845I
20
19
V
V
IN
D5
CC
38-LEAD (7mm × 5mm) PLASTIC QFN
G PACKAGE
TJMAX = 125°C, θJA = 34°C/ W
EXPOSED PAD IS VEE (PIN 39)
MUST BE SOLDERED TO PCB
36-LEAD PLASTIC SSOP
TJMAX = 125°C, θJA = 90°C/ W, θJC = 35°C/ W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the full operating tempera-
ture range, otherwise specifications are at TA = 25°C. VCC = 5V, VIN = 3.3V, VDD = 8V, VEE = – 7V for V.28, – 5.5V for V.10, V.11
(Notes 2, 3)
SYMBOL
Supplies
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
I
V
Supply Current (DCE Mode,
CC
RS530, RS530-A, X.21 Modes, No Load
RS530, RS530-A, X.21 Modes, Full Load
V.28 Mode, No Load
2.7
110
1
mA
mA
mA
mA
µA
CC
All Digital Pins = GND or V )
●
●
●
●
150
3
IN
V.28 Mode, Full Load
1
3
No-Cable Mode
700
1400
sn2845 2845fs
2
LTC2845
ELECTRICAL CHARACTERISTICS
(Notes 2, 3)
The ● denotes specifications which apply over the full operating tempera-
ture range, otherwise specifications are at TA = 25°C. VCC = 5V, VIN = 3.3V, VDD = 8V, VEE = – 7V for V.28, – 5.5V for V.10, V.11
SYMBOL
PARAMETER
Supply Current (DCE Mode,
CONDITIONS
MIN
TYP
MAX
UNITS
I
V
RS530, RS530-A, X.21 Modes, No Load
RS530, X.21 Modes, Full Load
RS530-A, Full Load
V.28 Mode, No Load
V.28 Mode, Full Load
2
mA
mA
mA
mA
mA
µA
EE
EE
All Digital Pins = GND or V )
23
34
1
IN
12
10
No-Cable Mode
I
I
V
Supply Current (DCE Mode,
DD
RS530, RS530-A, X.21 Modes, No Load
RS530, RS530-A, X.21 Modes, Full Load
V.28 Mode, No Load
0.3
0.3
1
mA
mA
mA
mA
µA
DD
All Digital Pins = GND or V )
IN
V.28 Mode, Full Load
13.5
10
No-Cable Mode
V
Supply Current (DCE Mode,
IN
All Modes Except No-Cable Mode
650
µA
VIN
All Digital Pins = GND or V )
IN
P
Internal Power Dissipation (DCE Mode,
RS530, RS530-A, X.21 Modes, Full Load
V.28 Mode, Full Load
240
64
mW
mW
D
All Digital Pins = GND or V )
IN
Logic Inputs and Outputs
V
V
Logic Input High Voltage
Logic Input Low Voltage
●
●
2
V
IH
IL
V
= 5V
0.8
0.5
V
V
CC
R4EN when V = 3.3V
CC
I
Logic Input Current
D1, D2, D3, D4, D5
●
●
●
±10
–120
±10
µA
µA
µA
IN
M0, M1, M2, DCE, D4ENB, R4EN = GND
–30
–75
M0, M1, M2, DCE, D4ENB, R4EN = V
IN
V
V
Output High Voltage
I = –3mA
●
●
●
2.7
3
V
V
OH
OL
O
Output Low Voltage
I = 1.6mA
O
0.2
0.4
I
I
Output Short-Circuit Current
Three-State Output Current
0V ≤ V ≤ V
IN
±50
mA
OSR
OZR
O
M0 = M1 = M2 = V , V = GND
M0 = M1 = M2 = V , V = V
IN
●
●
–30
–85
–160
±10
µA
µA
IN
IN
O
O
V.11 Driver
V
V
Open Circuit Differential Output Voltage
Loaded Differential Output Voltage
R = 1.95k (Figure 1)
●
±5
V
ODO
ODL
L
R = 50Ω (Figure 1)
L
0.5V
0.67V
ODO
V
V
ODO
●
●
±2
∆V
Change in Magnitude of Differential
Output Voltage
R = 50Ω (Figure 1)
L
0.2
V
OD
V
Common Mode Output Voltage
R = 50Ω (Figure 1)
●
●
3
V
V
OC
L
∆V
Change in Magnitude of Common Mode
Output Voltage
R = 50Ω (Figure 1)
L
0.2
OC
I
I
Short-Circuit Current
V
= GND
OUT
±150
±100
mA
SS
OZ
Output Leakage Current
–0.25V ≤ V ≤ 0.25V, Power Off or
No-Cable Mode or Driver Disabled
●
±1
µA
O
t , t
Rise or Fall Time
Input to Output
Input to Output
LTC2845C (Figures 2, 5)
LTC2845I (Figures 2, 5)
●
●
2
2
15
15
25
35
ns
ns
r
f
PLH
PHL
t
t
LTC2845C (Figures 2, 5)
LTC28451 (Figures 2, 5)
●
●
20
20
40
40
65
75
ns
ns
LTC2845C (Figures 2, 5)
LTC2845I (Figures 2, 5)
●
●
20
20
40
40
65
75
ns
ns
∆t
Input to Output Difference,
Output to Output Skew
t
– t
PHL
LTC2845C (Figures 2, 5)
LTC2845I (Figures 2, 5)
●
●
0
0
3
3
12
17
ns
ns
PLH
t
(Figures 2, 5)
3
ns
SKEW
sn2845 2845fs
3
LTC2845
ELECTRICAL CHARACTERISTICS
(Notes 2, 3)
The ● denotes specifications which apply over the full operating tempera-
ture range, otherwise specifications are at TA = 25°C. VCC = 5V, VIN = 3.3V, VDD = 8V, VEE = – 7V for V.28, – 5.5V for V.10, V.11
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V.11 Receiver
V
Input Threshold Voltage
Input Hysteresis
–7V ≤ V ≤ 7V
●
●
●
●
–0.2
0.2
40
V
mV
mA
kΩ
ns
TH
CM
∆V
–7V ≤ V ≤ 7V
15
TH
CM
I
Input Current (A, B)
Input Impedance
Rise or Fall Time
Input to Output
–10V ≤ V ≤ 10V
±0.66
IN
A,B
R
–10V ≤ V ≤ 10V
15
30
15
IN
A,B
t , t
r
(Figures 2, 6)
f
t
LTC2845C C = 50pF (Figures 2, 6)
●
●
50
50
80
90
ns
ns
PLH
L
LTC2845I C = 50pF (Figures 2, 6)
L
t
Input to Output
LTC2845C C = 50pF (Figures 2, 6)
●
●
50
50
80
90
ns
ns
PHL
L
LTC2845I C = 50pF (Figures 2, 6)
L
∆t
Input to Output Difference,
t
– t
PHL
LTC2845C C = 50pF (Figures 2, 6)
●
●
0
0
4
4
16
21
ns
ns
PLH
L
LTC2845I C = 50pF (Figures 2, 6)
L
V.10 Driver
V
V
Output Voltage
Output Voltage
Open Circuit, R = 3.9k
●
●
±4
±6
V
V
O
T
L
R = 450Ω (Figure 3)
±3.6
0.9V
L
R = 450Ω (Figure 3)
L
O
I
I
Short-Circuit Current
V = GND
±150
±100
mA
SS
OZ
O
Output Leakage Current
–0.25V ≤ V ≤ 0.25V, Power Off or
No-Cable Mode or Driver Disabled
●
±0.1
µA
O
t , t
Rise or Fall Time
Input to Output
Input to Output
R = 450Ω, C = 100pF (Figures 3, 7)
2
1
1
µs
µs
µs
r
f
PLH
PHL
L
L
t
t
R = 450Ω, C = 100pF (Figures 3, 7)
L L
R = 450Ω, C = 100pF (Figures 3, 7)
L
L
V.10 Receiver
V
Receiver Input Threshold Voltage
Receiver Input Hysteresis
Receiver Input Current
Receiver Input Impedance
Rise or Fall Time
●
●
●
●
–0.25
15
0.25
50
V
mV
mA
kΩ
ns
TH
∆V
25
TH
I
–10V ≤ V ≤ 10V
±0.66
IN
A
R
–10V ≤ V ≤ 10V
30
15
IN
A
t , t
C = 50pF (Figures 4, 8)
L
r
f
PLH
PHL
t
t
Input to Output
C = 50pF (Figures 4, 8)
L
55
ns
Input to Output
C = 50pF (Figures 4, 8)
L
109
60
ns
∆t
Input to Output Difference,
Output Voltage
t
– t
PHL
C = 50pF (Figures 4, 8)
L
ns
PLH
V.28 Driver
V
Open Circuit
R = 3k (Figure 3)
L
●
●
±10
V
V
O
±5
±8.5
±1
I
I
Short-Circuit Current
V = GND
O
●
●
±150
±100
mA
SS
OZ
Output Leakage Current
–0.25V ≤ V ≤ 0.25V, Power Off or
µA
O
No-Cable Mode or Driver Disabled
SR
Slew Rate
R = 3k, C = 2500pF (Figures 3, 7)
●
●
●
4
30
2.5
2.5
V/µs
µs
L
L
t
t
Input to Output
Input to Output
R = 3k, C = 2500pF (Figures 3, 7)
1.3
1.3
PLH
PHL
L
L
R = 3k, C = 2500pF (Figures 3, 7)
µs
L
L
sn2845 2845fs
4
LTC2845
The ● denotes specifications which apply over the full operating tempera-
ELECTRICAL CHARACTERISTICS
(Notes 2, 3)
ture range, otherwise specifications are at TA = 25°C. VCC = 5V, VIN = 3.3V, VDD = 8V, VEE = – 7V for V.28, – 5.5V for V.10, V.11
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V.28 Receiver
V
V
Input Low Threshold Voltage
Input High Threshold Voltage
Receiver Input Hysterisis
Receiver Input Impedance
Rise or Fall Time
●
●
●
●
0.8
V
V
THL
TLH
2
3
∆V
0.1
5
0.3
7
V
TH
R
–15V ≤ V ≤ 15V
kΩ
ns
ns
ns
IN
A
t , t
C = 50pF (Figures 4, 8)
L
15
60
150
r
f
PLH
PHL
t
t
Input to Output
C = 50pF (Figures 4, 8)
L
●
●
100
500
Input to Output
C = 50pF (Figures 4, 8)
L
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 3: All typicals are given for V = 5V, V = 3.3V, V = 8V, V = –7V
CC
IN
DD
EE
for V.28, –5.5V for V.10, V.11 and T = 25°C.
A
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.
U W
TYPICAL PERFOR A CE CHARACTERISTICS
RS530-A in DCE Mode
V.28 in DCE Mode
(Five V.28 Drivers with Full Load)
IDD vs Data Rate
RS530, X.21 in DCE Mode
(Three V.10 Drivers with Full
Load) IEE vs Data Rate
(Three V.11, Two V.10 Drivers
with Full Load) ICC vs Data Rate
34
34
30
28
26
24
22
20
18
140
135
130
125
120
115
110
105
16
15
14
13
12
11
10
9
T
= 25°C
T
= 25°C
T = 25°C
A
A
A
8
7
10
20
30 40 50 60 70 80 100
10
100
1000
10000
10
20
30 40 50 60 70 80 100
2845 G03
DATA RATE (kBd)
2845 G01
DATA RATE (kBd)
2845 G02
DATA RATE (kBd)
RS530-A in DCE Mode
(Three V.10 Drivers with Full
Load) IEE vs Temperature
V.28 in DCE Mode
(Five V.28 Drivers with Full Load)
IDD vs Temperature
RS530, X.21 in DCE Mode
(Three V.11, Two V.10 Drivers with
Full Load) ICC vs Temperature
125
120
115
110
105
100
95
34.6
34.4
34.2
34.0
33.8
33.6
33.4
33.2
33.0
13.9
13.8
13.7
13.6
13.5
13.4
13.3
13.2
13.1
–40 –20
0
20
40
60
80
100
–40 –20
0
20
40
60
80 100
–40 –20
0
20
40
60
80 100
2845 G04
2845 G05
2845 G06
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
sn2845 2845fs
5
LTC2845
U
U
U
(G-36/QFN-38 Packages)
PIN FUNCTIONS
VCC (Pins 1, 19/Pins 17, 36): Positive Supply for the
Transceivers. Connect to VCC Pin 8 on LTC2846 or to 5V
supply. Connect a 1µF capacitor to ground.
D5 (Pin 18/Pin 16): TTL Level Driver 5 Input.
VIN (Pin 20/Pin 18): Positive Supply for the Receiver
Outputs. 3V ≤ VIN ≤ 3.6V. Connect a 1µF capacitor to
ground.
VDD (Pin 2/Pin 37): Positive Supply Voltage for V.28.
Connect to VDD Pin 7 on LTC2846 or 8V supply. Connect
a 1µF capacitor to ground.
D5 A (Pin 21/Pin 19): Driver 5 Inverting Output.
R5 A (Pin 22/Pin 20): Receiver 5 Inverting Input.
R4 A (Pin 23/Pin 21): Receiver 4 Inverting Input.
D4 A (Pin 24/Pin 22): Driver 4 Inverting Input.
R3 B (Pin 25/Pin 23): Receiver 3 Noninverting Input.
R3 A (Pin 26/Pin 24): Receiver 3 Inverting Input.
R2 B (Pin 27/Pin 25): Receiver 2 Noninverting Input.
R2 A (Pin 28/Pin 26): Receiver 2 Inverting Input.
D1 (Pin 3/Pin 38): TTL Level Driver 1 Input.
D2 (Pin 4/Pin 1): TTL Level Driver 2 Input.
D3 (Pin 5/Pin 2): TTL Level Driver 3 Input.
R1 (Pin 6/Pin 3):CMOS Level Receiver 1 Output. Receiver
outputs have a weak pull up to VIN when high impedance.
R2 (Pin 7/Pin 4): CMOS Level Receiver 2 Output.
R3 (Pin 8/Pin 5): CMOS Level Receiver 3 Output.
D4 (Pin 9/Pin 6): TTL Level Driver 4 Input.
D3/R1 B (Pin 29/Pin 27): Receiver 1 Noninverting Input
and Driver 3 Noninverting Output.
R4 (Pin 10/Pin 7): CMOS Level Receiver 4 Output.
D3/R1 A (Pin 30/Pin 28): Receiver 1 Inverting Input and
Driver 3 Inverting Output.
M0 (Pin 11/Pin 8): TTL Level Mode Select Input 0. Mode
select inputs pull up to VIN.
D2 B (Pin 31/Pin 29): Driver 2 Noninverting Output.
D2 A (Pin 32/Pin 30): Driver 2 Inverting Output.
D1 B (Pin 33/Pin 31): Driver 1 Noninverting Output.
D1 A (Pin 34/Pin 32): Driver 1 Inverting Output.
GND (Pin 35/Pin 33): Ground.
M1 (Pin 12/Pin 9): TTL Level Mode Select Input 1.
M2 (Pin 13/Pin 10): TTL Level Mode Select Input 2.
DCE/DTE (Pin 14/Pin 12): TTL Level Mode Select Input.
Logic high enables Driver 3. Logic low enables Receiver 1.
D4ENB (Pin 15/Pin 13): TTL Level Enable Input. Logic low
enables Driver 4. Pulls up to VIN.
VEE (Pin 36/Pins 34, 35): Negative Supply Voltage. Con-
nect to VEE Pin 31 on LTC2846 or to –7V supply. Connect
a 1µF capacitor to ground.
R4EN (Pin 16/Pin 14): TTL Level Enable Input. Logic high
enables Receiver 4. Pulls up to VIN.
EXPOSED Pad VEE (Pin 39): Must be Soldered to PCB.
R5 (Pin 17/Pin 15): CMOS Level Receiver 5 Output.
sn2845 2845fs
6
LTC2845
W
BLOCK DIAGRA
TEST CIRCUITS
A
V
CC
1
36 V
EE
R
R
L
V
2
35 GND
34 D1A
DD
V
OD
D1
D2
3
4
D1
D2
V
OC
L
D1B
33
32 D2A
2845 F01
B
Figure 1. V.11 Driver Test Circuit
D2B
31
30 D3/R1 A
D3
5
D3
20k
20k
10k
10k
6k
S3
C
L
B
A
100pF
B
A
R
R
29 D3/R1 B
28 R2A
L
100Ω
R1
R2
6
7
R1
C
L
100pF
C
L
20k
6k
S3
10k
2845 F02
R2
Figure 2. V.11 Driver/Receiver AC Test Circuit
10k
20k
R2B
27
26 R3A
20k
10k
6k
S3
R3
D4
8
9
R3
D
A
10k
20k
R3B
25
R
C
L
L
D4
24 D4A
23 R4A
2845 F03
20k
20k
10k
10k
6k
R4 10
R4
Figure 3. V.10/V.28 Driver Test Circuit
S3
DCE/DTE
14
15
16
D4ENB
R4EN
22 R5A
6k
R5 17
R5
S3
D
A
A
R
D5 18
D5
21 D5A
C
L
M0 11
M1 12
M2 13
2845 F04
MODE
SELECTION
LOGIC
Figure 4. V.10/V.28 Receiver Test Circuit
V
V
20
19
IN
CC
2845 BD
sn2845 2845fs
7
LTC2845
W
U
ODE SELECTIO
(Note 1)
(Note 4) (Note 1)
(Note 4)
D4A
MODE NAME
M2
M1
M0
DCE
/DTE
D1, D2,
D4, D5
D3
D1
D2
D3
D5A
A
B
A
B
A
B
Not Used
(Default V.11)
RS530A
RS530
X.21
V.35
RS449/V.36
V.28/RS232
No Cable
Not Used
(Default V.11)
RS530A
RS530
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
0
0
0
0
0
0
0
TTL
TTL
TTL
TTL
TTL
TTL
TTL
X
X
X
X
X
X
X
X
X
V.11
V.11
V.11
V.11
V.28
V.11
V.28
Z
V.11
V.11
V.11
V.11
Z
V.11
Z
Z
V.11
V.10
V.11
V.11
V.28
V.11
V.28
Z
V.11
Z
V.11
V.11
Z
V.11
Z
Z
Z
Z
Z
Z
Z
Z
Z
Z
Z
Z
Z
Z
Z
Z
Z
Z
V.10
V.10
V.10
V.10
V.28
V.10
V.28
Z
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
1
1
1
1
1
1
1
1
TTL
TTL
TTL
TTL
TTL
TTL
TTL
X
TTL
TTL
TTL
TTL
TTL
TTL
TTL
X
V.11
V.11
V.11
V.11
V.28
V.11
V.28
Z
V.11
V.11
V.11
V.11
Z
V.11
Z
Z
V.11
V.10
V.11
V.11
V.28
V.11
V.28
Z
V.11
Z
V.11
V.11
Z
V.11
Z
Z
V.11
V.11
V.11
V.11
V.28
V.11
V.28
Z
V.11
V.11
V.11
V.11
Z
V.11
Z
Z
V.10
V.10
V.10
V.10
V.28
V.10
V.28
Z
X.21
V.35
RS449/V.36
V.28/RS232
No Cable
(Note 2)
(Note 3)
(Note 2)
R1
A
(Note 2)
R2
A
(Note 2)
R3
A
(Note 5) (Note 3) (Note 5)
MODE NAME
M2
M1
M0
DCE
/DTE
R4A
R5A
R1
R2, R3
R4, R5
B
B
B
Not Used
(Default V.11)
RS530A
RS530
X.21
V.35
RS449/V.36
V.28/RS232
No Cable
Not Used
(Default V.11)
RS530A
RS530
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
0
0
0
0
0
0
0
V.11
V.11
V.11
V.11
V.28
V.11
V.28
30k
V.11
V.11
V.11
V.11
30k
V.11
30k
30k
V.11
V.10
V.11
V.11
V.28
V.11
V.28
30k
V.11
30k
V.11
V.11
30k
V.11
30k
30k
V.11
V.11
V.11
V.11
V.28
V.11
V.28
30k
V.11
V.11
V.11
V.11
30k
V.11
30k
30k
V.10
V.10
V.10
V.10
V.28
V.10
V.28
30k
CMOS
CMOS
CMOS
CMOS
CMOS
CMOS
CMOS
Z
CMOS
CMOS
CMOS
CMOS
CMOS
CMOS
CMOS
Z
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
1
1
1
1
1
1
1
1
30k
30k
30k
30k
30k
30k
30k
30k
30k
30k
30k
30k
30k
30k
30k
30k
V.11
V.10
V.11
V.11
V.28
V.11
V.28
30k
V.11
30k
V.11
V.11
30k
V.11
30k
30k
V.11
V.11
V.11
V.11
V.28
V.11
V.28
30k
V.11
V.11
V.11
V.11
30k
V.11
30k
30k
V.10
V.10
V.10
V.10
V.28
V.10
V.28
30k
Z
Z
Z
Z
Z
Z
Z
Z
CMOS
CMOS
CMOS
CMOS
CMOS
CMOS
CMOS
Z
X.21
V.35
RS449/V.36
V.28/RS232
No Cable
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 when Z.
IN
Note 4: Driver 4 is enabled by D4ENB=0 (Pin 15).
Note 5: Receiver 4 is enabled by R4EN=1 (Pin 16).
sn2845 2845fs
8
LTC2845
U
W
W
SWITCHI G TI E WAVEFOR S
3V
f = 1MHz : t ≤ 10ns : t ≤ 10ns
r
f
1.5V
1.5V
D
0V
t
t
PHL
PLH
V
O
90%
90%
10%
V
= V(B) – V(A)
DIFF
B – A
50%
50%
10%
–V
O
1/2 V
O
t
t
r
f
A
V
O
B
t
t
2845 F05
SKEW
SKEW
Figure 5. V.11 Driver Propagation Delays
V
B – A
OD2
f = 1MHz : t ≤ 10ns : t ≤ 10ns
INPUT
r
f
0V
t
0V
–V
OD2
t
PLH
PHL
V
R
OH
OUTPUT
1.65V
1.65V
V
OL
2845 F06
Figure 6. V.11 Receiver Propagation Delays
3V
0V
D
1.5V
t
1.5V
PHL
3V
t
PLH
V
O
3V
2845 F07
0V
0V
A
–3V
–3V
–V
O
t
t
f
r
Figure 7. V.10, V.28 Driver Propagation Delays
V
IH
RECEIVER THRESHOLD
A
RECEIVER THRESHOLD
V
IL
t
PHL
t
PLH
V
OH
1.65V
1.65V
R
2845 F08
V
OL
Figure 8. V.10, V.28 Receiver Propagation Delays
sn2845 2845fs
9
LTC2845
U
W U U
APPLICATIONS INFORMATION
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 LTC2845
isusedtogeneratethecontrolsignalsalongwithLL(Local
Loop-Back), RL (Remote Loop-Back), TM (Test Mode)
and RI (Ring Indicate). Cable termination is used only for
theclockanddatasignalsbecausetheymustsupportV.11
cable termination. The control signals do not need any
external resistors.
Overview
The LTC2846/LTC2845 or LTC2847/LTC2845 form the
core of a complete software-selectable DTE or DCE inter-
faceportthatsupportstheRS232,RS449,EIA530,EIA530-
A, V.35, V.36 or X.21 protocols. Cable termination is
provided on-chip, eliminating the need for discrete de-
signs.
DTE
DCE
SERIAL
CONTROLLER
LTC2846
LTC2846
SERIAL
CONTROLLER
103Ω R3
D1
D2
D3
TXD
TXD
TXD
SCTE
103Ω R2
SCTE
SCTE
R1
D3
TXC
RXC
RXD
R1
103Ω
103Ω
103Ω
TXC
RXC
RXD
TXC
RXC
R2
R3
D2
D1
RXD
LTC2845
D1
LTC2845
R3
RTS
DTR
RTS
DTR
RTS
DTR
D2
D3
R2
R1
D3
DCD
DSR
R1
R2
R3
DCD
DSR
CTS
DCD
DSR
D2
D1
CTS
CTS
LL
LL
LL
D4
R4
R4
D4
TM
TM
TM
RI
RI
R5
D5
RI
D5
R5
RL
RL
RL
2845 F09
Figure 9. Complete Multiprotocol Interface in EIA530 Mode
sn2845 2845fs
10
LTC2845
U
W U U
APPLICATIONS INFORMATION
Mode Selection
Cable Termination
The interface protocol is selected using the mode select
pins M0, M1 and M2 (see the Mode Selection table).
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
withtheterminationinthecableheadorseparatetermina-
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.
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
operateinV.28(RS232)electricalmode. Fortheclockand
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.
Theinterfaceprotocolmaybeselectedsimplybyplugging
the appropriate interface cable into the connector. The
mode pins are routed to the connector and are left uncon-
nected (1) or wired to ground (0) in the cable as shown in
Figure 10.
Using the LTC2846/LTC2845 solves the cable termination
switching problem. Via software control, appropriate ter-
minationfortheV.10(RS423),V.11(RS422),V.28(RS232)
and V.35 electrical protocols is chosen.
The internal pull-up current sources will ensure a binary 1
when a pin is left unconnected and that the LTC2846/
LTC2845 enters the no-cable mode when the cable is
removed. In the no-cable mode the LTC2846/LTC2845
supply current drops to less than 1000µA and all driver
outputs are forced into a high impedance state.
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
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.
' con-
'
The mode selection may also be accomplished by using
jumpers to connect the mode pins to ground or VIN.
(DATA)
M0
CONNECTOR
LTC2846
M1
M2
NC
NC
DCE/DTE
CABLE
V
IN
DCE/DTE
M2
M1
M0
D4ENB
R4EN
LTC2845
3.3k
(DATA)
2845 F10
Figure 10. Single Port DCE V.35 Mode Selection in the Cable
sn2845 2845fs
11
LTC2845
U
W U U
APPLICATIONS INFORMATION
The V.10 receiver configuration in the LTC2845 is shown
in Figure 13. In V.10 mode switch S3 inside the LTC2845
is turned off. The noninverting input is disconnected
inside the LTC2845 receiver and connected to ground.The
cable termination is then the 30k input impedance to
ground of the LTC2845 V.10 receiver.
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
groundC',inputsA'connectedtoA,B'connectedtoB.The
V.11 interface has a differential termination at the receiver
end that has a minimum value of 100Ω. The termination
resistor is optional in the V.11 specification, but for the
highspeedclockanddatalines,theterminationisrequired
to prevent reflections from corrupting the data. The
receiver inputs must also be compliant with the imped-
ance curve shown in Figure 12.
BALANCED
INTERCONNECTING
CABLE
LOAD
GENERATOR
CABLE
TERMINATION
RECEIVER
A
A'
In V.11 mode, all switches are off except S1 of the
LTC2846’s receivers which connects a 103Ω differential
termination impedance to the cable as shown in Fig-
ure 151. The LTC2845 only handles control signals, so no
terminationotherthanitsV.11receivers’30kinputimped-
ance is necessary.
2845 F11
C
C'
Figure 11. Typical V.10 Interface
I
Z
3.25mA
BALANCED
INTERCONNECTING
CABLE
LOAD
GENERATOR
CABLE
TERMINATION
RECEIVER
–10V
–3V
A
A'
V
Z
100Ω
MIN
3V
10V
B
C
B'
C'
2845 F14
Figure 14. Typical V.11 Interface
2845 F12
–3.25mA
Figure 12. V.10 Receiver Input Impedance
A'
LTC2846
R5
20k
R1
51.5Ω
R8
6k
A'
LTC2845
R6
RECEIVER
10k
R5
20k
S1
S2
R8
6k
S3
R3
124Ω
R6
10k
RECEIVER
S3
R7
10k
R2
51.5Ω
R4
20k
B'
R7
10k
R4
20k
C'
2845 F15
GND
B'
C'
Figure 15. V.11 Receiver Configuration
GND
2845 F13
1Actually, 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.
Figure 13. V.10 Receiver Configuration
sn2845 2845fs
12
LTC2845
U
W U U
APPLICATIONS INFORMATION
V.28 (RS232) Interface
ground C is connected to a differential receiver with
groundC',inputsA'connectedtoA,B'connectedtoB.The
A typical V.28 unbalanced interface is shown in Figure 16.
A V.28 single-ended generator output A with ground C is
V.35 interface requires a T or delta network termination at
the receiver end and the generator end. The receiver
differentialimpedancemeasuredattheconnectormustbe
100Ω ±10Ω, and the impedance between shorted termi-
connected to a single-ended receiver with input A
'
con-
nected to A, ground C
ground C.
' connected via the signal return
nals (A' and B') and ground C' must be 150Ω ±15Ω.
In V.28 mode, all switches are off except S3 inside the
LTC2846/LTC2845 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/
LTC2845 receiver and connected to a TTL level reference
voltage for a 1.4V receiver trip point.
InV.35mode,bothswitchesS1andS2insidetheLTC2846
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 50Ω to
150Ω and the impedance between shorted terminals (A
and B) and ground C must be 150Ω ±15Ω. For the
generator termination, switches S1 and S2 are both on as
shown in Figure 20.
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
BALANCED
INTERCONNECTING
CABLE
GENERATOR
LOAD
BALANCED
CABLE
TERMINATION
INTERCONNECTING
RECEIVER
CABLE
LOAD
GENERATOR
A'
A
CABLE
TERMINATION
RECEIVER
50Ω
50Ω
125Ω
125Ω
A
A'
50Ω
50Ω
B
'
B
C
C'
2845 F16
C
C'
2845 F18
Figure 16. Typical V.28 Interface
Figure 18. Typical V.35 Interface
A'
A
'
LTC2845
LTC2846
R5
20k
R5
20k
R1
R8
6k
R8
6k
51.5Ω
R6
10k
R6
10k
RECEIVER
RECEIVER
S3
S1
S2
S3
R3
124Ω
R7
10k
R7
10k
R2
51.5Ω
R4
20k
R4
20k
B'
C'
B
'
2845 F19
GND
GND
C
'
2845 F17
Figure 17. V.28 Receiver Configuration
Figure 19. V.35 Receiver Configuration
sn2845 2845fs
13
LTC2845
U
W U U
APPLICATIONS INFORMATION
A
LTC2846
DTE vs DCE Operation
51.5Ω
The DCE/DTE pin acts as an enable for Driver 3/Receiver 1
in the LTC2846, and Driver 3/Receiver 1 in the LTC2845.
S1
V.35 DRIVER
124Ω
S2
The LTC2846/LTC2845 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
operationbyreroutingthesignalstotheLTC2846/LTC2845
using a dedicated DTE cable or dedicated DCE cable.
51.5Ω
B
C
2845 F20
Figure 20. V.35 Driver
No-Cable Mode
A dedicated DTE port using a DB-25 male connector is
showninFigure23.Theinterfacemodeisselectedbylogic
outputs from the controller or from jumpers to either VIN
or GND on the mode select pins. A dedicated DCE port
using a DB-25 female connector is shown in Figure 24.
A port with one DB-25 connector, can be configured for
either DTE or DCE operation is shown in Figure 25. The
configuration requires separate cables for proper signal
routing in DTE or DCE operation. For example, in DTE
mode,theTXDsignalisroutedtoPins2and14viaDriver 1
intheLTC2846.InDCEmode,Driver1nowroutestheRXD
signal to Pins 2 and 14.
The no-cable mode (M0=M1=M2=D4ENB=1, R4EN = 0)
is intended for the case when the cable is disconnected
from the connector. The bias circuitry, drivers and receiv-
ers are turned off, the driver outputs are forced into a high
impedancestate, andthesupplycurrentdropstolessthan
700µA.
LTC2846 and LTC2847 Supplies
The LTC2846 and LTC2847 use an internal capacitive
charge pump to generate VDD and VEE as shown in Figure
21. A voltage doubler generates about 8V on VDD and a
voltage inverter generates about –7.5V for VEE. Three 1µF
surface mounted tantalum or ceramic capacitors are re-
quired for C1, C2 and C3. The VEE capacitor C4 should be
a minimum of 3.3µF. 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
showninFigure22.The5VVCC suppliesitsinternalcharge
pump and transceivers as well as its companion chip. The
LTC2847 requires an external 5V supply.
Compliance Testing
The LTC2846/LTC2845 chipset has been tested by TUV
Rheinland of North America Inc. and passed the NET1,
NET2andTBR2requirements.Copiesofthetestreportare
availablefromLTCorTUVRheinlandofNorthAmericaInc.
The title of the report is Test Report No.TBR2/050101/02
The address of TUV Rheinland of North America Inc. is:
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
Receiver Fail-Safe
All LTC2846/LTC2845 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.
L1
5.6µH
D1
V
CC
V
IN
3.3V
5V
480mA
+
V
C2
C2
V
DD
+
V
SW
R1
13k
C6
10µF
IN
C2
1µF
C3
1µF
BOOST
–
SWITCHING
REGULATOR
C5
10µF
C1
C1
V
LTC2846
OR
LTC2847
C1
1µF
SHDN
SHDN
FB
–
R2
4.3k
EE
GND
C4
3.3µF
+
GND
5V
CC
C1,C2: TAIYO YUDEN X5R JMK316BJ106ML
D1: ON SEMICONDUCTOR MBR0520
L1: SUMIDA CR43-5R6
C5
10µF
2845 F22
2845 F21
Figure 21. Charge Pump
Figure 22. LTC2846 Boost Switching Regulator
sn2845 2845fs
14
LTC2845
U
TYPICAL APPLICATIONS
L1
5.6µH
D1 MBR0520
V
V
CC
5V
IN
3.3V
C6
R1
10µF
13k
BOOST
SWITCHING
REGULATOR
C5
10µF
SHDN
R2
4.3k
V
8V
DD
C2
C3
1µF
1µF
C1
1µF
V
EE
CHARGE
PUMP
–7.5V
C4
V
CC
+
3.3µF
5V
LTC2846
2
TXD A (103)
TXD
D1
D2
D3
T
T
T
14
TXD B
24
SCTE A (113)
SCTE
11
SCTE B
15
TXC A (114)
TXC
RXC
RXD
R1
R2
R3
12
17
TXC B
RXC A (115)
T
T
9
3
RXC B
RXD A (104)
16
7
RXD B
SG
M0
M1
M2
V
IN
3.3V
1
DCE/DTE
SHIELD
DB-25 MALE
CONNECTOR
V
V
EE
GND
CC
C9
1µF
C7
1µF
V
DD
C8
1µF
4
RTS A (105)
RTS B
RTS
D1
D2
D3
19
20
23
DTR A (108)
DTR B
DTR
LTC2845
8
10
6
DCD A (109)
DCD B
R1
R2
R3
DCD
DSR
DSR A (107)
DSR B
22
5
CTS A (106)
CTS B
CTS
LL
13
18
*
D4
LL (141)
RI (125)
R4
R5
RI
25
21
TM (142)
RL (140)
TM
RL
D5
V
IN
M0
M1
M2
M0
M1
M2
V
IN
D4ENB
3.3V
C10
1µF
*OPTIONAL
NC
DCE/DTE R4EN
2845 F23
Figure 23. Controller-Selectable Multiprotocol DTE Port with DB-25 Connector
sn2845 2845fs
15
LTC2845
U
TYPICAL APPLICATIONS
L1
5.6µH
D1 MBR0520
V
V
CC
5V
IN
3.3V
C6
R1
10µF
13k
BOOST
SWITCHING
REGULATOR
C5
10µF
SHDN
R2
4.3k
V
8V
DD
C2
C3
1µF
1µF
C1
1µF
V
CHARGE
PUMP
EE
–7.5V
C4
V
+
CC
3.3µF
5V
LTC2846
2
RXD A (104)
RXD
RXC
D1
D2
D3
T
T
T
14
RXD B
24
RXC A (115)B
11
RXC B
15
TXC A (114)
TXC
SCTE
TXD
R1
R2
R3
12
24
TXC B
SCTE A (113)
T
T
11
2
SCTE B
TXD A (103)
14
7
TXD B
M0
M1
M2
V
IN
SG (102)
3.3V
1
DCE/DTE
NC
SHIELD (101)
DB-25 FEMALE
CONNECTOR
V
V
EE
GND
CC
C9
1µF
C7
1µF
V
DD
C8
1µF
5
CTS A (106)
CTS B
CTS
D1
D2
D3
13
6
DSR A (107)
DSR B
22
DSR
LTC2845
8
10
20
23
DCD A (109)
DCD B
R1
R2
R3
DCD
DTR
DTR A (108)
DTR B
4
RTS A (105)
RTS B
RTS
RI
19
*
D4
RI (125)
LL (141)
18
R4
R5
LL
21
25
RL (140)
TM (142)
RL
D5
TM
V
IN
M0
M1
M2
M0
M1
M2
V
IN
D4ENB
3.3V
C10
1µF
*OPTIONAL
DCE/DTE R4EN
NC
NC
2845 F24
Figure 24. Controller-Selectable DCE Port with DB-25 Connector
sn2845 2845fs
16
LTC2845
U
TYPICAL APPLICATIONS
L1
5.6µH
D1 MBR0520
V
V
CC
5V
IN
3.3V
C6
R1
10µF
13k
BOOST
SWITCHING
REGULATOR
C5
10µF
SHDN
R2
4.3k
V
8V
DD
C2
C3
1µF
1µF
C1
1µF
V
CHARGE
PUMP
EE
–7.5V
C4
V
+
CC
3.3µF
5V
DTE
DCE
LTC2846
2
14
TXD A
RXD A
DTE_TXD/DCE_RXD
DTE_SCTE/DCE_RXC
D1
D2
D3
T
T
T
TXD B
RXD B
RXC A
24
SCTE A
11
SCTE B
RXC B
15
TXC A
TXC A
DTE_TXC/DCE_TXC
DTE_RXC/DCE_SCTE
DTE_RXD/DCE_TXD
R1
R2
R3
12
17
TXC B
RXC A
TXC B
SCTE A
T
T
9
3
RXC B
RXD A
SCTE B
TXD A
16
7
RXD B
SG
TXD B
M0
M1
M2
V
IN
3.3V
1
DCE/DTE
SHIELD
DB-25
CONNECTOR
V
V
EE
GND
CC
C9
1µF
C7
1µF
V
DD
C8
1µF
4
RTS A
CTS A
CTS B
DSR A
DSR B
DTE_RTS/DCE_CTS
DTE_DTR/DCE_DSR
D1
D2
D3
19
20
23
RTS B
DTR A
DTR B
LTC2845
8
10
6
DCD A
DCD B
DCD A
DCD B
R1
R2
R3
DTE_DCD/DCE_DCD
DTE_DSR/DCE_DTR
DSR A
DSR B
CTS A
CTS B
DTR A
DTR B
RTS A
RTS B
22
5
DTE_CTS/DCE_RTS
DTE_LL/DCE_RI
DTE_RI/DCE_LL
13
18
*
D4
LL
RI
RI
R4
R5
LL
25
21
TM
RL
RL
DTE_TM/DCE_RL
DTE_RL/DCE_TM
D5
TM
V
IN
M0
M1
M0
M1
M2
V
IN
D4ENB
3.3V
C10
1µF
M2
NC
*OPTIONAL
DCE/DTE
DCE/DTE R4EN
2845 F25
Figure 25. Controller-Selectable Multiprotocol DTE/DCE Port with DB-25 Connector
sn2845 2845fs
17
LTC2845
U
PACKAGE DESCRIPTION
G Package
36-Lead Plastic SSOP (5.3mm)
(Reference LTC DWG # 05-08-1640)
12.50 – 13.10*
(.492 – .516)
1.25 ±0.12
36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19
7.8 – 8.2
5.3 – 5.7
7.40 – 8.20
(.291 – .323)
0.42 ±0.03
0.65 BSC
5
7
8
RECOMMENDED SOLDER PAD LAYOUT
1
2
3
4
6
9 10 11 12 13 14 15 16 17 18
5.00 – 5.60**
(.197 – .221)
2.0
(.079)
0° – 8°
0.65
(.0256)
BSC
0.09 – 0.25
(.0035 – .010)
0.55 – 0.95
(.022 – .037)
0.05
0.22 – 0.38
(.009 – .015)
(.002)
G36 SSOP 0802
NOTE:
1. CONTROLLING DIMENSION: MILLIMETERS
MILLIMETERS
2. DIMENSIONS ARE IN
(INCHES)
3. DRAWING NOT TO SCALE
*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
sn2845 2845fs
18
LTC2845
U
PACKAGE DESCRIPTIO
UHF Package
38-Lead Plastic QFN (5mm × 7mm)
(Reference LTC DWG # 05-08-1701)
0.70 ± 0.05
5.50 ± 0.05
(2 SIDES)
4.10 ± 0.05
(2 SIDES)
3.20 ± 0.05
(2 SIDES)
PACKAGE
OUTLINE
0.25 ± 0.05
0.50 BSC
5.20 ± 0.05 (2 SIDES)
6.10 ± 0.05 (2 SIDES)
7.50 ± 0.05 (2 SIDES)
RECOMMENDED SOLDER PAD LAYOUT
3.15 ± 0.10
(2 SIDES)
0.75 ± 0.05
5.00 ± 0.10
(2 SIDES)
0.435 0.18
0.18
37 38
0.00 – 0.05
PIN 1
TOP MARK
(SEE NOTE 6)
1
2
0.23
5.15 ± 0.10
(2 SIDES)
7.00 ± 0.10
(2 SIDES)
0.40 ± 0.10
0.200 REF 0.25 ± 0.05
R = 0.115
TYP
(UH) QFN 0303
0.50 BSC
0.200 REF
0.75 ± 0.05
BOTTOM VIEW—EXPOSED PAD
0.00 – 0.05
NOTE:
1. DRAWING CONFORMS TO JEDEC PACKAGE
OUTLINE M0-220 VARIATION WHKD
2. DRAWING NOT TO SCALE
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.20mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION
ON THE TOP AND BOTTOM OF PACKAGE
3. ALL DIMENSIONS ARE IN MILLIMETERS
sn2845 2845fs
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-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
19
LTC2845
U
TYPICAL APPLICATIO
DTE or DCE Multiprotocol Serial Interface with DB-25 Connector
RL TM
RI
LL CTS
DSR
DCD
DTR
RTS
TXC
SCTE
TXD
RXD
RXC
LTC2846
LTC2845
D3
D2
D1
D3
D2
T
D1
T
D5
R5
D4
R3
R2
R1
R4
R3
T
R2
T
R1
T
21
25
*
18 13
5
10
8
22
6
23 20 19
4
1
7
16
3
9
17
12
15 11
24 14
2
*OPTIONAL
DB-25 CONNECTOR
2845 TA01
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC1321
Dual RS232/RS485 Transceiver
Two RS232 Driver/Receiver Pairs or Two RS485 Driver/Receiver Pairs
Two RS232 Driver/Receiver or Four RS232 Driver/Receiver Pairs
4-Driver/4-Receiver for Data and Clock Signals
LTC1334
Single 5V RS232/RS485 Multiprotocol Transceiver
Software-Selectable Multiprotocol Transceiver
Software-Selectable Cable Terminator
Single Supply V.35 Transceiver
LTC1343
LTC1344A
LTC1345
Perfect for Terminating the LTC1543 (Not Needed with LTC1546)
3-Driver/3-Receiver for Data and Clock Signals
LTC1346A
LTC1543
Dual Supply V.35 Transceiver
3-Driver/3-Receiver for Data and Clock Signals
Software-Selectable Multiprotocol Transceiver
Terminated with LTC1344A for Data and Clock Signals, Companion to
LTC1544 or LTC1545 for Control Signals
LTC1544
LTC1545
Software-Selectable Multiprotocol Transceiver
Software-Selectable Multiprotocol Transceiver
Companion to LTC1546 or LTC1543 for Control Signals Including LL
5-Driver/5-Receiver Companion to LTC1546 or LTC1543
for Control Signals Including LL, TM and RL
LTC1546
LTC2844
Software-Selectable Multiprotocol Transceiver
3-Driver/3-Receiver with Termination for Data and Clock Signals
3.3V Software-Selectable Multiprotocol Transceiver
3.3V Supply, 4-Driver/4-Receiver Companion to LTC2846 for Control
Signals Including LL
LTC2846
LTC2847
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
Software-Selectable Multiprotocol Transceiver
with 3.3V Digital Interface
3-Driver/3-Receiver with Termination for Data and Clock Signals.
Seperate Supply for Digital Interface Works Down to 3.3V
sn2845 2845fs
LT/TP 0703 1K • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
20
●
●
LINEAR TECHNOLOGY CORPORATION 2002
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
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