LTC2845
3.3V Software-Selectable
Multiprotocol Transceiver
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FEATURES
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DESCRIPTIO
The LTC®2845 is a 5-driver/5-receiver multiprotocol transceiver. 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.
The LTC2845 operates from a 3.3V supply and supplies
provided by the LTC2846. This part is available in a 36-lead
SSOP and 38-lead (7mm x 5mm) QFN package. The LTC2845
and LTC2847 in QFN packages offer the smallest multiprotocol
serial port available.
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
Complete DTE or DCE Port with LTC2846 or LTC2847
Available in a 36-Lead Narrow (0.209") SSOP and
38-Lead (7mm x 5mm) QFN package
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APPLICATIO S
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Data Networking
CSU and DSU
Data Routers
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, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
DTE or DCE Multiprotocol Serial Interface with DB-25 Connector
RL
TM
RI
LL
CTS
DSR
DCD
DTR
RTS
D2
D1
RXD
TXC
D4
R5
21
25
R4
*
D3
R2
R3
18 13 5
22 6
TXD
D3
D2
D1
T
T
T
12
15 11
24 14
LTC2846
LTC2845
D5
SCTE
RXC
R1
10 8
23 20 19 4
1
R2
T
T
16
3
9
R1
17
2
TXD A (103)
TXD B
SCTE A (113)
SCTE B
TXC A (114)
TXC B
RXC A (115)
RXC B
RXD A (104)
RXD B
SG (102)
SHIELD (101)
RTS A (105)
RTS B
DTR A (108)
DTR B
DCD A (109)
DCD B
DSR A (107)
DSR B
CTS A (106)
CTS B
LL A (141)
RI A (125)
TM A (142)
RL A (140)
DB-25 CONNECTOR
7
R3
*OPTIONAL
2845 TA01
sn2845 2845fs
1
LTC2845
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W W
W
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Supply Voltage
VCC ....................................................... –0.3V to 6.5V
VIN ..................................................................... – 0.3V to 6.5V
VEE ...................................................................... –10V to 0.3V
VDD ..................................................................... – 0.3V to 10V
Input Voltage
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)
Short-Circuit Duration
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
W
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PACKAGE/ORDER INFORMATION
34 D1 A
D2
4
D4
9
R1
R4 10
R2
M0 11
M1 12
R3
M2 13
DCE/DTE 14
D4
R4
D4ENB 15
D4 6
28 R2 A
R4 7
27 R2 B
M0 8
24 R3 A
26 R3 A
M1 9
23 R3 B
25 R3 B
M2 10
22 D4 A
24 D4 A
NC 11
21 R4 A
23 R4 A
DCE/DTE 12
22 R5 A
R5
R5 17
D5
26 R2 A
39
25 R2 B
UHF PART
MARKING
20 R5 A
2845
2845I
13 14 15 16 17 18 19
21 D5 A
R4EN 16
D5 18
27 D3/R1 B
29 D3/R1 B
LTC2845CUHF
LTC2845IUHF
20 VIN
19 VCC
D5 A
8
28 D3/R1 A
R3 5
VIN
R3
R2 4
30 D3/R1 A
31 D2 B
D3
29 D2 B
VCC
7
30 D2 A
R1 3
D5
R2
D2
31 D1 B
D3 2
R5
6
32 D2 A
LTC2845CG
LTC2845IG
R4EN
5
R1
33 D1 B
38 37 36 35 34 33 32
D2 1
D4ENB
D3
D1
D1 A
35 GND
3
GND
2
D1
ORDER PART
NUMBER
TOP VIEW
VEE
VDD
ORDER PART
NUMBER
VEE
36 VEE
VCC
1
VDD
VCC
D1
TOP VIEW
UHF PACKAGE
38-LEAD (7mm × 5mm) PLASTIC QFN
TJMAX = 125°C, θJA = 34°C/ W
EXPOSED PAD IS VEE (PIN 39)
MUST BE SOLDERED TO PCB
G PACKAGE
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 temperature 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
PARAMETER
CONDITIONS
VCC Supply Current (DCE Mode,
All Digital Pins = GND or VIN)
RS530, RS530-A, X.21 Modes, No Load
RS530, RS530-A, X.21 Modes, Full Load
V.28 Mode, No Load
V.28 Mode, Full Load
No-Cable Mode
MIN
TYP
MAX
UNITS
2.7
110
1
1
700
150
3
3
1400
mA
mA
mA
mA
µA
Supplies
ICC
●
●
●
●
sn2845 2845fs
2
LTC2845
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the full operating temperature 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
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
IEE
VEE Supply Current (DCE Mode,
All Digital Pins = GND or VIN)
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
No-Cable Mode
2
23
34
1
12
10
mA
mA
mA
mA
mA
µA
IDD
VDD Supply Current (DCE Mode,
All Digital Pins = GND or VIN)
RS530, RS530-A, X.21 Modes, No Load
RS530, RS530-A, X.21 Modes, Full Load
V.28 Mode, No Load
V.28 Mode, Full Load
No-Cable Mode
0.3
0.3
1
13.5
10
mA
mA
mA
mA
µA
IVIN
VIN Supply Current (DCE Mode,
All Digital Pins = GND or VIN)
All Modes Except No-Cable Mode
650
µA
PD
Internal Power Dissipation (DCE Mode,
All Digital Pins = GND or VIN)
RS530, RS530-A, X.21 Modes, Full Load
V.28 Mode, Full Load
240
64
mW
mW
Logic Inputs and Outputs
VIH
Logic Input High Voltage
VIL
Logic Input Low Voltage
VCC = 5V
R4EN when VCC = 3.3V
●
IIN
Logic Input Current
D1, D2, D3, D4, D5
M0, M1, M2, DCE, D4ENB, R4EN = GND
M0, M1, M2, DCE, D4ENB, R4EN = VIN
●
●
●
–30
–75
2.7
3
●
VOH
Output High Voltage
IO = –3mA
●
VOL
Output Low Voltage
IO = 1.6mA
●
IOSR
Output Short-Circuit Current
0V ≤ VO ≤ VIN
●
IOZR
Three-State Output Current
M0 = M1 = M2 = VIN, VO = GND
M0 = M1 = M2 = VIN, VO = VIN
●
●
●
2
–30
V
0.8
0.5
V
V
±10
–120
±10
µA
µA
µA
V
0.2
0.4
V
±50
mA
–85
–160
±10
µA
µA
V.11 Driver
VODO
Open Circuit Differential Output Voltage
RL = 1.95k (Figure 1)
VODL
Loaded Differential Output Voltage
RL = 50Ω (Figure 1)
●
0.5VODO
±2
±5
V
0.67VODO
V
V
0.2
V
∆VOD
Change in Magnitude of Differential
Output Voltage
RL = 50Ω (Figure 1)
●
VOC
Common Mode Output Voltage
RL = 50Ω (Figure 1)
●
3
V
∆VOC
Change in Magnitude of Common Mode
Output Voltage
RL = 50Ω (Figure 1)
●
0.2
V
ISS
Short-Circuit Current
VOUT = GND
IOZ
Output Leakage Current
–0.25V ≤ VO ≤ 0.25V, Power Off or
No-Cable Mode or Driver Disabled
●
tr, tf
Rise or Fall Time
LTC2845C (Figures 2, 5)
LTC2845I (Figures 2, 5)
●
●
tPLH
Input to Output
LTC2845C (Figures 2, 5)
LTC28451 (Figures 2, 5)
tPHL
Input to Output
∆t
tSKEW
±150
mA
±1
±100
µA
2
2
15
15
25
35
ns
ns
●
●
20
20
40
40
65
75
ns
ns
LTC2845C (Figures 2, 5)
LTC2845I (Figures 2, 5)
●
●
20
20
40
40
65
75
ns
ns
Input to Output Difference, tPLH – tPHL
LTC2845C (Figures 2, 5)
LTC2845I (Figures 2, 5)
●
●
0
0
3
3
12
17
ns
ns
Output to Output Skew
(Figures 2, 5)
3
ns
sn2845 2845fs
3
LTC2845
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the full operating temperature 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
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V.11 Receiver
VTH
Input Threshold Voltage
–7V ≤ VCM ≤ 7V
●
∆VTH
Input Hysteresis
–7V ≤ VCM ≤ 7V
●
IIN
Input Current (A, B)
–10V ≤ VA,B ≤ 10V
●
RIN
Input Impedance
–10V ≤ VA,B ≤ 10V
●
tr, tf
Rise or Fall Time
(Figures 2, 6)
tPLH
Input to Output
LTC2845C CL = 50pF (Figures 2, 6)
LTC2845I CL = 50pF (Figures 2, 6)
●
●
50
50
80
90
ns
ns
tPHL
Input to Output
LTC2845C CL = 50pF (Figures 2, 6)
LTC2845I CL = 50pF (Figures 2, 6)
●
●
50
50
80
90
ns
ns
∆t
Input to Output Difference, tPLH – tPHL
LTC2845C CL = 50pF (Figures 2, 6)
LTC2845I CL = 50pF (Figures 2, 6)
●
●
4
4
16
21
ns
ns
–0.2
15
15
0
0
0.2
V
40
mV
±0.66
mA
30
kΩ
15
ns
V.10 Driver
±4
±6
VO
Output Voltage
Open Circuit, RL = 3.9k
●
VT
Output Voltage
RL = 450Ω (Figure 3)
RL = 450Ω (Figure 3)
●
V
ISS
Short-Circuit Current
VO = GND
IOZ
Output Leakage Current
–0.25V ≤ VO ≤ 0.25V, Power Off or
No-Cable Mode or Driver Disabled
tr, tf
Rise or Fall Time
RL = 450Ω, CL = 100pF (Figures 3, 7)
2
µs
tPLH
Input to Output
RL = 450Ω, CL = 100pF (Figures 3, 7)
1
µs
tPHL
Input to Output
RL = 450Ω, CL = 100pF (Figures 3, 7)
1
µs
±3.6
0.9VO
V
±0.1
●
±150
mA
±100
µA
V.10 Receiver
VTH
Receiver Input Threshold Voltage
●
∆VTH
Receiver Input Hysteresis
●
IIN
Receiver Input Current
–10V ≤ VA ≤ 10V
●
RIN
Receiver Input Impedance
–10V ≤ VA ≤ 10V
●
tr, tf
Rise or Fall Time
CL = 50pF (Figures 4, 8)
tPLH
Input to Output
tPHL
Input to Output
∆t
–0.25
0.25
25
15
V
50
mV
±0.66
mA
30
kΩ
15
ns
CL = 50pF (Figures 4, 8)
55
ns
CL = 50pF (Figures 4, 8)
109
ns
Input to Output Difference, tPLH – tPHL
CL = 50pF (Figures 4, 8)
60
ns
VO
Output Voltage
Open Circuit
RL = 3k (Figure 3)
●
●
ISS
Short-Circuit Current
VO = GND
●
IOZ
Output Leakage Current
–0.25V ≤ VO ≤ 0.25V, Power Off or
No-Cable Mode or Driver Disabled
●
SR
Slew Rate
RL = 3k, CL = 2500pF (Figures 3, 7)
●
tPLH
Input to Output
RL = 3k, CL = 2500pF (Figures 3, 7)
●
tPHL
Input to Output
RL = 3k, CL = 2500pF (Figures 3, 7)
●
V.28 Driver
±5
±8.5
±1
4
±10
V
V
±150
mA
±100
µA
30
V/µs
1.3
2.5
µs
1.3
2.5
µs
sn2845 2845fs
4
LTC2845
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the full operating temperature 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
PARAMETER
V.28 Receiver
VTHL
Input Low Threshold Voltage
VTLH
Input High Threshold Voltage
∆VTH
Receiver Input Hysterisis
RIN
Receiver Input Impedance
tr, tf
Rise or Fall Time
tPLH
Input to Output
tPHL
Input to Output
CONDITIONS
MIN
TYP
●
●
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.
UNITS
0.8
V
V
V
kΩ
ns
ns
ns
2
●
–15V ≤ VA ≤ 15V
CL = 50pF (Figures 4, 8)
CL = 50pF (Figures 4, 8)
CL = 50pF (Figures 4, 8)
MAX
3
●
●
●
0.1
5
15
60
150
0.3
7
100
500
Note 3: All typicals are given for VCC = 5V, VIN = 3.3V, VDD = 8V, VEE = – 7V
for V.28, – 5.5V for V.10, V.11 and TA = 25°C.
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TYPICAL PERFOR A CE CHARACTERISTICS
RS530-A in DCE Mode
(Three V.10 Drivers with Full
Load) IEE vs Data Rate
RS530, X.21 in DCE Mode
(Three V.11, Two V.10 Drivers
with Full Load) ICC vs Data Rate
V.28 in DCE Mode
(Five V.28 Drivers with Full Load)
IDD vs Data Rate
34
140
16
TA = 25°C
TA = 25°C
135
130
34
15
30
14
13
120
IDD (mA)
IEE (mA)
ICC (mA)
28
125
26
24
115
20
105
18
125
100
1000
DATA RATE (kBd)
2845 G01
120
IEE (mA)
ICC (mA)
115
110
105
100
20
60
0
40
TEMPERATURE (°C)
80
100
2845 G04
7
30 40 50 60 70 80 100
20
DATA RATE (kBd)
2845 G02
RS530-A in DCE Mode
(Three V.10 Drivers with Full
Load) IEE vs Temperature
RS530, X.21 in DCE Mode
(Three V.11, Two V.10 Drivers with
Full Load) ICC vs Temperature
95
–40 –20
8
10
10000
11
9
34.6
13.9
34.4
13.8
34.2
13.7
34.0
13.6
33.8
13.4
33.4
13.3
33.2
13.2
0
20
40
60
TEMPERATURE (°C)
20
30 40 50 60 70 80 100
2845 G03
DATA RATE (kBd)
13.5
33.6
33.0
–40 –20
10
V.28 in DCE Mode
(Five V.28 Drivers with Full Load)
IDD vs Temperature
IDD (mA)
10
12
10
22
110
TA = 25°C
80
100
2845 G05
13.1
–40 –20
0
20
40
60
TEMPERATURE (°C)
80
100
2845 G06
sn2845 2845fs
5
LTC2845
U
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PIN FUNCTIONS
(G-36/QFN-38 Packages)
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.
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.
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.
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.
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 (Pin 7/Pin 4): CMOS Level Receiver 2 Output.
R2 B (Pin 27/Pin 25): Receiver 2 Noninverting Input.
R3 (Pin 8/Pin 5): CMOS Level Receiver 3 Output.
R2 A (Pin 28/Pin 26): Receiver 2 Inverting Input.
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.
M0 (Pin 11/Pin 8): TTL Level Mode Select Input 0. Mode
select inputs pull up to VIN.
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.
D3/R1 A (Pin 30/Pin 28): Receiver 1 Inverting Input and
Driver 3 Inverting Output.
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.
R4EN (Pin 16/Pin 14): TTL Level Enable Input. Logic high
enables Receiver 4. Pulls up to VIN.
VEE (Pin 36/Pins 34, 35): Negative Supply Voltage. Connect to VEE Pin␣ 31 on LTC2846 or to –7V supply. Connect
a 1µF capacitor to ground.
R5 (Pin 17/Pin 15): CMOS Level Receiver 5 Output.
EXPOSED Pad VEE (Pin 39): Must be Soldered to PCB.
sn2845 2845fs
6
LTC2845
W
BLOCK DIAGRA
TEST CIRCUITS
A
VCC 1
36 VEE
VDD 2
35 GND
RL
34 D1A
D1 3
VOD
D1
32 D2A
D2 4
D2
VOC
RL
33 D1B
B
2845 F01
Figure 1. V.11 Driver Test Circuit
31 D2B
30 D3/R1 A
D3
5
D3
10k
20k
6k
S3
10k
20k
29 D3/R1 B
R1
6
R1
B
RL
100Ω
A
CL
100pF
B
CL
100pF
A
R
28 R2A
20k
CL
6k
10k
R2 7
S3
R2
2845 F02
Figure 2. V.11 Driver/Receiver AC Test Circuit
10k
27 R2B
20k
26 R3A
20k
6k
10k
R3
8
S3
R3
D
10k
A
25 R3B
D4
9
D4
RL
CL
20k
24 D4A
23 R4A
10k
R4 10
20k
2845 F03
6k
Figure 3. V.10/V.28 Driver Test Circuit
R4
S3
DCE/DTE 14
D4ENB 15
22 R5A
R4EN 16
10k
R5 17
20k
6k
R5
S3
D
D5 18
D5
21 D5A
A
A
R
CL
M0 11
M1 12
2845 F04
MODE
SELECTION
LOGIC
Figure 4. V.10/V.28 Receiver Test Circuit
M2 13
20 VIN
19 VCC
2845 BD
sn2845 2845fs
7
LTC2845
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ODE SELECTIO
MODE NAME
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
X.21
V.35
RS449/V.36
V.28/RS232
No Cable
MODE NAME
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
X.21
V.35
RS449/V.36
V.28/RS232
No Cable
M2
M1
M0
DCE
/DTE
(Note 1)
(Note 4) (Note 1)
D1, D2,
D3
D4, D5
D1
D2
(Note 4)
D4A
D5A
D3
A
B
A
B
A
B
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
(Note 2)
R1
A
B
(Note 2)
R2
A
B
(Note 2)
R3
A
B
(Note 2)
(Note 3)
(Note 5) (Note 3) (Note 5)
R4A
R1
R2, R3
R5A
R4, R5
M2
M1
M0
DCE
/DTE
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
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 VIN when Z.
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 r ≤ 10ns : t f ≤ 10ns
1.5V
D
0V
1.5V
t PHL
t PLH
VO
B–A
–VO
90%
50%
10%
90%
VDIFF = V(B) – V(A)
50%
1/2 VO
tr
10%
tf
A
VO
B
t SKEW
t SKEW
2845 F05
Figure 5. V.11 Driver Propagation Delays
VOD2
B–A
–VOD2
f = 1MHz : t r ≤ 10ns : t f ≤ 10ns
0V
INPUT
t PLH
VOH
R
VOL
0V
t PHL
OUTPUT
1.65V
1.65V
2845 F06
Figure 6. V.11 Receiver Propagation Delays
3V
1.5V
1.5V
D
0V
VO
t PHL
t PLH
3V
3V
0V
A
0V
–3V
–VO
2845 F07
–3V
tf
tr
Figure 7. V.10, V.28 Driver Propagation Delays
VIH
RECEIVER THRESHOLD
A
VIL
VOH
R
VOL
t PHL
RECEIVER THRESHOLD
t PLH
1.65V
1.65V
2845 F08
Figure 8. V.10, V.28 Receiver Propagation Delays
sn2845 2845fs
9
LTC2845
U
U
W
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
is used to generate the control signals along with LL (Local
Loop-Back), RL (Remote Loop-Back), TM (Test Mode)
and RI (Ring Indicate). Cable termination is used only for
the clock and data signals because they must support V.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 interface port that supports the RS232, RS449, EIA530, EIA530A, V.35, V.36 or X.21 protocols. Cable termination is
provided on-chip, eliminating the need for discrete designs.
SERIAL
CONTROLLER
DTE
DCE
LTC2846
LTC2846
SERIAL
CONTROLLER
TXD
D1
TXD
103Ω
R3
TXD
SCTE
D2
SCTE
103Ω
R2
SCTE
R1
D3
TXC
R1
103Ω
TXC
D3
TXC
RXC
R2
103Ω
RXC
D2
RXC
RXD
R3
103Ω
RXD
D1
RXD
LTC2845
LTC2845
RTS
D1
RTS
R3
RTS
DTR
D2
DTR
R2
DTR
D3
R1
DCD
R1
DCD
D3
DCD
DSR
R2
DSR
D2
DSR
CTS
R3
CTS
D1
CTS
LL
TM
RI
RL
LL
D4
R4
TM
R4
R5
D5
RI
RL
D4
D5
R5
LL
TM
RI
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
with the termination in the cable head or separate terminations 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
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 plugging
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.
Using the LTC2846/LTC2845 solves the cable termination
switching problem. Via software control, appropriate termination for the V.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' connected 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 mode selection may also be accomplished by using
jumpers to connect the mode pins to ground or VIN.
CONNECTOR
(DATA)
M0
LTC2846
M1
M2
NC
DCE/DTE
NC
DCE/DTE
VIN
CABLE
M2
M1
LTC2845
M0
D4ENB
3.3k
R4EN
(DATA)
2845 F10
Figure 10. Single Port DCE V.35 Mode Selection in the Cable
sn2845 2845fs
11
LTC2845
U
U
W
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.
BALANCED
INTERCONNECTING
CABLE
GENERATOR
LOAD
CABLE
TERMINATION
A
A'
C
C'
RECEIVER
2845 F11
Figure 11. Typical V.10 Interface
IZ
3.25mA
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 100Ω. 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 impedance curve shown in Figure 12.
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 Figure␣ 151. The LTC2845 only handles control signals, so no
termination other than its V.11 receivers’ 30k input impedance is necessary.
BALANCED
INTERCONNECTING
CABLE
GENERATOR
LOAD
CABLE
TERMINATION
–3V
–10V
A
A'
B
B'
C
C'
RECEIVER
VZ
3V
100Ω
MIN
10V
2845 F14
Figure 14. Typical V.11 Interface
2845 F12
–3.25mA
Figure 12. V.10 Receiver Input Impedance
A'
LTC2846
R1
51.5Ω
A'
R8
6k
LTC2845
R8
6k
R6
10k
R5
20k
S1
S2
R6
10k
S3
R4
20k
R3
124Ω
RECEIVER
S3
RECEIVER
B'
B'
R5
20k
R7
10k
C'
R2
51.5Ω
R4
20k
R7
10k
GND
2845 F15
Figure 15. V.11 Receiver Configuration
C'
GND
2845 F13
Figure 13. V.10 Receiver Configuration
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.
sn2845 2845fs
12
LTC2845
U
U
W
U
APPLICATIONS INFORMATION
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' connected to A, ground C' connected via the signal return
ground C.
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.
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
100Ω␣ ±10Ω, and the impedance between shorted terminals (A' and B') and ground C' must be 150Ω ±15Ω.
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 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.
BALANCED
INTERCONNECTING
CABLE
GENERATOR
BALANCED
INTERCONNECTING
CABLE
GENERATOR
LOAD
CABLE
TERMINATION
A'
A
50Ω
125Ω
50Ω
125Ω
50Ω
C'
C
RECEIVER
RECEIVER
A'
A
LOAD
CABLE
TERMINATION
50Ω
2845 F16
B
B'
C
C'
2845 F18
Figure 16. Typical V.28 Interface
A'
LTC2845
R8
6k
Figure 18. Typical V.35 Interface
A'
R5
20k
R6
10k
S3
LTC2846
R1
51.5Ω
R6
10k
RECEIVER
S1
S2
R4
20k
B'
C'
R8
6k
R5
20k
R7
10k
B'
GND
C'
R3
124Ω
RECEIVER
S3
R2
51.5Ω
R4
20k
R7
10k
GND
2845 F19
2845 F17
Figure 17. V.28 Receiver Configuration
Figure 19. V.35 Receiver Configuration
sn2845 2845fs
13
LTC2845
U
U
W
U
APPLICATIONS INFORMATION
A
LTC2846
51.5Ω
V.35 DRIVER
124Ω
S1
S2
51.5Ω
B
C
2845 F20
Figure 20. V.35 Driver
No-Cable Mode
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 receivers are turned off, the driver outputs are forced into a high
impedance state, and the supply current drops to less than
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 required 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
shown in Figure 22. The 5V VCC supplies its internal charge
pump and transceivers as well as its companion chip. The
LTC2847 requires an external 5V supply.
Receiver Fail-Safe
All LTC2846/LTC2845 receivers feature fail-safe operation 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 in the LTC2845.
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
operation by rerouting the signals to the LTC2846/LTC2845
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 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, 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.
Compliance Testing
The LTC2846/LTC2845 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.TBR2/050101/02
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
L1
5.6µH
VIN
3.3V
C3
1µF
C1
1µF
VDD
C2 +
C1+
C2 –
C1–
LTC2846
OR
LTC2847
C2
1µF
SHDN
VEE
+
VCC
5V
C6
10µF
C4
3.3µF
D1
SW
BOOST
SWITCHING
REGULATOR
SHDN
FB
GND
VIN
VCC
5V
480mA
R1
13k
C5
10µF
R2
4.3k
GND
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
VIN
3.3V
C6
10µF
SHDN
VDD 8V
C3
1µF
D1 MBR0520
VCC
5V
R1
13k
BOOST
SWITCHING
REGULATOR
R2
4.3k
C5
10µF
C2
1µF
C1
1µF
CHARGE
PUMP
VCC
5V
VEE
–7.5V
C4
3.3µF
+
LTC2846
2
TXD
D1
T
SCTE
D2
T
D3
11
R1
12
17
T
R2
RXC
9
3
RXD
SCTE B
T
15
TXC
TXD A (103)
14 TXD B
24
SCTE A (113)
T
R3
16
M0
VIN
3.3V
M1
7
TXC A (114)
TXC B
RXC A (115)
RXC B
RXD A (104)
RXD B
SG
M2
1
DCE/DTE
C7
1µF
C8
1µF
VCC
VEE
VDD
GND
DB-25 MALE
CONNECTOR
C9
1µF
4
RTS
D1
19
20
D2
DTR
SHIELD
23
RTS A (105)
RTS B
DTR A (108)
DTR B
D3
LTC2845
8
DCD
R1
10
DSR
R2
22
6
5
R3
CTS
13
18
D4
LL
RI
R4
TM
R5
*
25
21
D5
RL
M0
M0
VIN
M1
M1
D4ENB
M2
M2
DCE/DTE
R4EN
C10
1µF
NC
DCD A (109)
DCD B
DSR A (107)
DSR B
CTS A (106)
CTS B
LL (141)
RI (125)
TM (142)
RL (140)
VIN
3.3V
*OPTIONAL
2845 F23
Figure 23. Controller-Selectable Multiprotocol DTE Port with DB-25 Connector
sn2845 2845fs
15
LTC2845
U
TYPICAL APPLICATIONS
L1
5.6µH
VIN
3.3V
C6
10µF
SHDN
VDD 8V
C3
1µF
D1 MBR0520
VCC
5V
R1
13k
BOOST
SWITCHING
REGULATOR
R2
4.3k
C5
10µF
C2
1µF
C1
1µF
CHARGE
PUMP
VCC
5V
VEE
–7.5V
C4
3.3µF
+
LTC2846
2
RXD
D1
T
RXC
D2
T
D3
11
R1
12
24
T
R2
SCTE
11
2
TXD
RXC B
T
15
TXC
RXD A (104)
14 RXD B
24
RXC A (115)B
T
R3
14
M0
VIN
3.3V
M1
7
TXC A (114)
TXC B
SCTE A (113)
SCTE B
TXD A (103)
TXD B
SG (102)
M2
NC
C7
1µF
C8
1µF
1
DCE/DTE
VCC
VEE
VDD
GND
DB-25 FEMALE
CONNECTOR
C9
1µF
5
CTS
D1
13
6
D2
DSR
SHIELD (101)
22
CTS A (106)
CTS B
DSR A (107)
DSR B
D3
LTC2845
DCD
R1
DTR
R2
8
10
20
23
4
R3
RTS
19
*
D4
RI
LL
R4
RL
R5
18
21
25
D5
TM
M0
M0
VIN
M1
M1
D4ENB
M2
M2
NC
DCE/DTE
R4EN
C10
1µF
DCD A (109)
DCD B
DTR A (108)
DTR B
RTS A (105)
RTS B
RI (125)
LL (141)
RL (140)
TM (142)
VIN
3.3V
NC
*OPTIONAL
2845 F24
Figure 24. Controller-Selectable DCE Port with DB-25 Connector
sn2845 2845fs
16
LTC2845
U
TYPICAL APPLICATIONS
L1
5.6µH
VIN
3.3V
C6
10µF
SHDN
VDD 8V
C3
1µF
D1 MBR0520
VCC
5V
R1
13k
BOOST
SWITCHING
REGULATOR
R2
4.3k
C5
10µF
C2
1µF
C1
1µF
CHARGE
PUMP
VCC
5V
VEE
–7.5V
C4
3.3µF
+
DTE
LTC2846
DTE_TXD/DCE_RXD
D1
2
T
14
24
DTE_SCTE/DCE_RXC
D2
T
D3
11
R1
12
17
T
R2
DTE_RXC/DCE_SCTE
9
3
DTE_RXD/DCE_TXD
RXD A
TXD B
RXD B
SCTE A
RXC A
SCTE B
RXC B
TXC A
TXC A
T
15
DTE_TXC/DCE_TXC
DCE
TXD A
T
R3
16
M0
VIN
3.3V
M1
7
TXC B
TXC B
RXC A
SCTE A
RXC B
SCTE B
RXD A
TXD A
RXD B
TXD B
SG
M2
1
DCE/DTE
C7
1µF
C8
1µF
VCC
VEE
VDD
GND
DB-25
CONNECTOR
C9
1µF
4
DTE_RTS/DCE_CTS
D1
19
20
D2
DTE_DTR/DCE_DSR
SHIELD
23
RTS A
CTS A
RTS B
CTS B
DTR A
DSR A
DTR B
DSR B
DCD A
DCD B
DCD A
DCD B
DSR A
DTR A
DSR B
DTR B
CTS A
RTS A
CTS B
RTS B
D3
LTC2845
8
DTE_DCD/DCE_DCD
R1
10
DTE_DSR/DCE_DTR
R2
22
6
5
R3
DTE_CTS/DCE_RTS
13
18
D4
DTE_LL/DCE_RI
DTE_RI/DCE_LL
R4
DTE_TM/DCE_RL
R5
*
25
21
D5
DTE_RL/DCE_TM
M0
M0
VIN
M1
M1
D4ENB
M2
M2
DCE/DTE
DCE/DTE
R4EN
C10
1µF
NC
LL
RI
RI
LL
TM
RL
RL
TM
VIN
3.3V
*OPTIONAL
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
7.8 – 8.2
36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19
5.3 – 5.7
7.40 – 8.20
(.291 – .323)
0.42 ±0.03
0.65 BSC
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
RECOMMENDED SOLDER PAD LAYOUT
5.00 – 5.60**
(.197 – .221)
2.0
(.079)
0° – 8°
0.09 – 0.25
(.0035 – .010)
0.55 – 0.95
(.022 – .037)
0.65
(.0256)
BSC
0.22 – 0.38
(.009 – .015)
0.05
(.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
5.00 ± 0.10
(2 SIDES)
3.15 ± 0.10
(2 SIDES)
0.75 ± 0.05
0.00 – 0.05
0.435 0.18
0.18
37 38
PIN 1
TOP MARK
(SEE NOTE 6)
1
0.23
2
5.15 ± 0.10
(2 SIDES)
7.00 ± 0.10
(2 SIDES)
0.40 ± 0.10
0.200 REF 0.25 ± 0.05
0.200 REF
0.00 – 0.05
0.75 ± 0.05
NOTE:
1. DRAWING CONFORMS TO JEDEC PACKAGE
OUTLINE M0-220 VARIATION WHKD
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
0.50 BSC
R = 0.115
TYP
(UH) QFN 0303
BOTTOM VIEW—EXPOSED PAD
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
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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
19
LTC2845
U
TYPICAL APPLICATIO
DTE or DCE Multiprotocol Serial Interface with DB-25 Connector
RL
TM
RI
LL
CTS
DSR
DCD
DTR
RTS
D2
D1
RXD
TXC
D4
R5
21
25
R4
*
D3
R2
R3
18 13 5
R1
10 8
TXD
D3
D2
D1
T
T
T
12
15 11
24 14
LTC2846
LTC2845
D5
SCTE
RXC
22 6
23 20 19 4
1
7
R3
R2
T
T
16
3
9
R1
17
2
TXD A (103)
TXD B
SCTE A (113)
SCTE B
TXC A (114)
TXC B
RXC A (115)
RXC B
RXD A (104)
RXD B
SG (102)
SHIELD (101)
RTS A (105)
RTS B
DTR A (108)
DTR B
DCD A (107)
DCD B
DSR A (109)
DSR B
CTS A (106)
CTS B
LL A (141)
RI A (125)
TM A (142)
RL A (140)
DB-25 CONNECTOR
*OPTIONAL
2845 TA01
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
LTC2844
3.3V Software-Selectable Multiprotocol Transceiver
3.3V Supply, 4-Driver/4-Receiver Companion to LTC2846 for Control
Signals Including LL
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
LTC2847
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
20
Linear Technology Corporation
LT/TP 0703 1K • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
LINEAR TECHNOLOGY CORPORATION 2002
工商网监
湘ICP备2023018690号
