LTC2846
3.3V Software-Selectable
Multiprotocol Transceiver
with Termination
FEATURES
s
s
s
DESCRIPTIO
s
s
s
s
s
Software-Selectable Transceiver Supports:
RS232, RS449, EIA530, EIA530-A, V.35, V.36, X.21
Operates from Single 3.3V Supply
TUV Rheinland of North America Inc. Certified NET1,
NET2 and TBR2 Compliant, Report No.:
TBR2/050101/02, TBR2/051501/02
1.2MHz Boost Switching Regulator for 3.3V to 5V
Conversion
On-Chip Cable Termination
Complete DTE or DCE Port with LTC2844 or LTC2845
Small Footprint
Available in 36-Lead SSOP (0.209 Wide) Package
APPLICATIO S
s
s
s
The LTC
®
2846 is a 3-driver/3-receiver multiprotocol trans-
ceiver with on-chip cable termination. When combined with
the LTC2844 or LTC2845, this chip set forms a complete
software-selectable DTE or DCE interface port that supports
the RS232, RS449, EIA530, EIA530-A, V.35, V.36 and X.21
protocols. All necessary cable termination is provided inside
the LTC2846. The LTC2846 has a boost regulator that takes
in a 3.3V input and switches at 1.2MHz, allowing the use of
tiny, low cost capacitors and inductors 2mm or less in height.
The 5V output drives an internal charge pump that requires
only five space-saving surface mounted capacitors. The
LTC2846 is available in a 36-lead SSOP surface mount
package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Data Networking
CSU and DSU
Data Routers
TYPICAL APPLICATIO
LL
CTS
DSR
Complete DTE or DCE Multiprotocol Serial Interface with DB-25 Connector
DCD
DTR
RTS
RXD
RXC
TXC
SCTE
TXD
LTC2844
D4
R4
R3
R2
R1
D3
D2
D1
R3
R2
LTC2846
D3
R1
D2
D1
T
T
18
13 5
22 6
10 8
23 20 19 4
1
7
16
3
9
17
DB-25 CONNECTOR
2846 TA01
U
T
T
T
12
15 11
24 14
2
U
U
DSR B
DSR A (107)
LL A (141)
CTS B
CTS A (106)
DTR B
DTR A (108)
RTS B
RTS A (105)
SHIELD (101)
SG (102)
DCD B
DCD A (109)
TXC B
TXC A (114)
SCTE B
SCTE A (113)
TXD B
TXD A (103)
RXD B
RXD A (104)
RXC B
RXC A (115)
sn2846 2846fs
1
LTC2846
ABSOLUTE
(Note 1)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
NC
PGND
V
IN
SHDN
C1
–
C1
+
V
DD
V
CC
D1
1
2
3
4
5
6
7
8
9
D1
D2 10
D3 11
R1 12
R2 13
R3 14
M0 15
M1 16
V
IN
17
M2 18
R2
T
R3
20 R3 B
19 DCE/DTE
R1
T
22 R2 B
21 R3 A
D2
D3
T
T
T
24 D3/R1 B
23 R2 A
CHARGE PUMP
BOOST
SWITCHING
REGULATOR
36 SW
35 FB
34 SGND
33 C2
+
32 C2
–
31 V
EE
30 GND
29 D1 A
28 D1 B
27 D2 A
26 D2 B
25 D3/R1 A
V
CC
Voltage.............................................. – 0.3V to 6.5V
V
IN
Voltage .............................................. – 0.3V to 6.5V
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)
V
EE
........................................................ – 10V to 0.3V
V
DD
....................................................... – 0.3V to 10V
Short-Circuit Duration
Transmitter Output ..................................... Indefinite
Receiver Output .......................................... Indefinite
V
EE
.................................................................. 30 sec
SW Voltage ............................................... – 0.4V to 36V
FB Voltage ............................................... – 0.3V to 2.5V
Current into FB Pin ..............................................
±1mA
SHDN Voltage ........................................... – 0.3V to 10V
Operating Temperature Range
LTC2846C ............................................... 0°C to 70°C
LTC2846I ........................................... – 40°C to 85°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
ORDER PART
NUMBER
LTC2846CG
LTC2846IG
G PACKAGE
36-LEAD PLASTIC SSOP
T
JMAX
= 125°C,
θ
JA
= 90°C/W,
θ
JC
= 35°C/W
*θ
JA
SOLDERED TO A CIRCUIT BOARD IS TYPICALLY 60°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
SYMBOL
Supplies
I
CC
V
CC
Supply Current (DCE Mode,
All Digital Pins = GND or V
IN
)
PARAMETER
The
q
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V, V
IN
= 3.3V, V
SHDN
= V
IN
, unless otherwise noted. (Notes 2, 3)
CONDITIONS
RS530, RS530-A, X.21 Modes, No Load
RS530, RS530-A, X.21 Modes, Full Load
V.35 Mode
V.28 Mode, No Load
V.28 Mode, Full Load
No-Cable Mode
RS530, RS530-A, X.21 Modes, Full Load
V.35 Mode, Full Load
V.28 Mode, Full Load
V.11 or V.28 Mode, No Load
V.35 Mode
V.28 Mode, with Load
V.28 Mode, with Load, I
DD
= 10mA
q
q
q
MIN
TYP
14
100
126
20
35
300
550
775
200
MAX
UNITS
mA
mA
mA
mA
mA
µA
mW
mW
mW
V
V
V
V
sn2846 2846fs
q
q
q
q
130
170
75
900
P
D
Internal Power Dissipation (DCE Mode)
V
+
Positive Charge Pump Output Voltage
8
7
8
9.3
8.0
8.7
6.5
2
U
W
U
U
W W
W
LTC2846
ELECTRICAL CHARACTERISTICS
SYMBOL
V
–
PARAMETER
Negative Charge Pump Output Voltage
The
q
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V, V
IN
= 3.3V, V
SHDN
= V
IN
, unless otherwise noted. (Notes 2, 3)
CONDITIONS
V.28 Mode, No Load
V.28 Mode, Full Load
V.35 Mode
RS530, RS530-A, X.21 Modes, Full Load
No-Cable Mode/Power-Off to Normal Operation
D1, D2, D3, M0, M1, M2, DCE/DTE
SHDN
D1, D2, D3, M0, M1, M2, DCE/DTE
SHDN
D1, D2, D3
M0, M1, M2, DCE/DTE = GND
M0, M1, M2, DCE/DTE = V
IN
SHDN = GND
SHDN = 3V
I
O
= – 3mA
I
O
= 1.6mA
0V
≤
V
O
≤
V
IN
M0 = M1 = M2 = V
IN
, V
O
= GND
M0 = M1 = M2 = V
IN
, V
O
= V
IN
R
L
= 1.95k (Figure 1)
R
L
= 50Ω (Figure 1)
R
L
= 50Ω (Figure 1)
R
L
= 50Ω (Figure 1)
R
L
= 50Ω (Figure 1)
R
L
= 50Ω (Figure 1)
V
OUT
= GND
V
A
and
V
B
≤
0.25V, Power Off or
q
q
q
q
q
q
q
q
q
q
q
q
q
MIN
– 7.5
– 5.5
– 4.5
TYP
– 9.6
– 8.5
– 6.5
– 6.0
500
2
MAX
UNITS
V
V
V
V
kHz
ms
V
V
f
OSC
t
r
V
IH
V
IL
I
IN
Charge Pump Oscillator Frequency
Charge Pump Rise Time
Logic Input High Voltage
Logic Input Low Voltage
Logic Input Current
Logic Inputs and Outputs
2.0
2.4
0.8
0.5
– 30
– 75
±10
– 120
±10
±0.1
32
0.4
±50
–30
–85
–160
±10
±
5
0.5V
ODO
±2
0.67V
ODO
0.2
3
0.2
±150
±
1
2
15
15
0
15
40
40
3
3
±100
25
65
65
12
V
V
µA
µA
µA
µA
µA
V
V
mA
µA
µA
V
V
V
V
V
V
mA
µA
ns
ns
ns
ns
ns
16
q
q
q
q
q
V
OH
V
OL
I
OSR
I
OZR
V.11 Driver
V
ODO
V
ODL
∆V
OD
V
OC
∆V
OC
I
SS
I
OZ
t
r
, t
f
t
PLH
t
PHL
∆t
t
SKEW
Output High Voltage
Output Low Voltage
Output Short-Circuit Current
Three-State Output Current
2.7
3
0.2
Open Circuit Differential Output Voltage
Loaded Differential Output Voltage
Change in Magnitude of Differential
Output Voltage
Common Mode Output Voltage
Change in Magnitude of Common Mode
Output Voltage
Short-Circuit Current
Output Leakage Current
Rise or Fall Time
Input to Output Rising
Input to Output Falling
Input to Output Difference,
t
PLH
– t
PHL
Output to Output Skew
q
q
q
q
q
No-Cable Mode or Driver Disabled
(Figures 2, 13)
(Figures 2, 13)
(Figures 2, 13)
(Figures 2, 13)
(Figures 2, 13)
sn2846 2846fs
3
LTC2846
ELECTRICAL CHARACTERISTICS
SYMBOL
V
TH
∆V
TH
R
IN
t
r
, t
f
t
PLH
t
PHL
∆t
V.35 Driver
V
OD
V
OA
, V
OB
V
OC
I
OH
I
OL
I
OZ
R
OD
R
OC
t
r
, t
f
t
PLH
t
PHL
∆t
t
SKEW
V
TH
∆V
TH
R
ID
R
IC
t
r
, t
f
t
PLH
t
PHL
∆t
V.28 Driver
V
O
I
SS
R
OZ
SR
t
PLH
t
PHL
Output Voltage
Short-Circuit Current
Power-Off Resistance
Slew Rate
Input to Output
Input to Output
Differential Output Voltage
Single-Ended Output Voltage
Transmitter Output Offset
Transmitter Output High Current
Transmitter Output Low Current
Transmitter Output Leakage Current
Transmitter Differential Mode Impedance
Transmitter Common Mode Impedance
Rise or Fall Time
Input to Output
Input to Output
Input to Output Difference,
t
PLH
– t
PHL
Output to Output Skew
Differential Receiver Input Threshold Voltage
Receiver Input Hysteresis
Receiver Differential Mode Impedance
Receiver Common Mode Impedance
Rise or Fall Time
Input to Output
Input to Output
Input to Output Difference,
t
PLH
– t
PHL
PARAMETER
Input Threshold Voltage
Input Hysteresis
Input Impedance
Rise or Fall Time
Input to Output Rising
Input to Output Falling
Input to Output Difference,
t
PLH
– t
PHL
V.11 Receiver
The
q
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V, V
IN
= 3.3V, V
SHDN
= V
IN
, unless otherwise noted. (Notes 2, 3)
CONDITIONS
– 7V
≤
V
CM
≤
7V
– 7V
≤
V
CM
≤
7V
–7V
≤
V
CM
≤
7V (Figure 3)
C
L
= 50pF (Figures 4, 14)
C
L
= 50pF (Figures 4, 14)
C
L
= 50pF (Figures 4, 14)
C
L
= 50pF (Figures 4, 14)
Open Circuit, R
L
= 1.95k (Figure 5)
With Load, – 4V
≤
V
CM
≤
4V (Figure 6)
Open Circuit, R
L
= 1.95k (Figure 5)
R
L
= 50Ω (Figure 5)
V
A
, V
B
= 0V
V
A
, V
B
= 0V
V
A
and
V
B
≤
0.25V
q
q
q
q
q
q
MIN
– 0.2
TYP
MAX
0.2
UNITS
V
mV
Ω
ns
15
100
103
15
50
50
0
4
40
90
90
25
±1.2
±0.66
±1.2
±0.6
ns
ns
ns
V
V
V
V
mA
mA
µA
Ω
Ω
ns
ns
ns
ns
ns
q
±0.44
q
q
q
q
q
q
±0.55
–9
9
50
135
– 11
11
±1
100
150
5
35
35
0
4
– 13
13
±100
150
165
65
65
16
– 2V
≤
V
CM
≤
2V (Figure 7)
(Figures 8, 13)
(Figures 8, 13)
(Figures 8, 13)
(Figures 8, 13)
(Figures 8, 13)
– 2V
≤
V
CM
≤
2V (Figure 9)
– 2V
≤
V
CM
≤
2V (Figure 9)
– 2V
≤
V
CM
≤
2V
– 2V
≤
V
CM
≤
2V (Figure 10)
C
L
= 50pF (Figures 4, 14)
C
L
= 50pF (Figures 4, 14)
C
L
= 50pF (Figures 4, 14)
C
L
= 50pF (Figures 4, 14)
Open Circuit
R
L
= 3k (Figure 11)
V
OUT
= GND
– 2V < V
O
< 2V, Power Off
or No-Cable Mode
R
L
= 7k, C
L
= 0 (Figures 11, 15)
R
L
= 3k, C
L
= 2500pF (Figures 11, 15)
R
L
= 3k, C
L
= 2500pF (Figures 11, 15)
q
q
q
q
q
q
q
q
q
15
15
V.35 Receiver
– 0.2
15
90
135
103
150
15
50
50
0
4
90
90
25
±10
±150
300
4
1.5
1.5
30
2.5
2.5
0.2
40
110
165
V
mV
Ω
Ω
ns
ns
ns
ns
V
V
mA
Ω
V/µs
µs
µs
sn2846 2846fs
q
q
q
q
q
q
q
±5
±8.5
4
LTC2846
ELECTRICAL CHARACTERISTICS
SYMBOL
PARAMETER
V.28 Receiver
V
THL
Input Low Threshold Voltage
V
TLH
Input High Threshold Voltage
∆V
TH
Receiver Input Hysteresis
R
IN
Receiver Input Impedance
t
r
, t
f
Rise or Fall Time
t
PLH
Input to Output
t
PHL
Input to Output
Boost Switching Regulator (Note 4)
V
IN
Operating Voltage
V
FB
Feedback Voltage
I
FB
FB Pin Bias Current
I
Q
Quiescent Current
Quiescent Current in Shutdown
∆V
FB(LR)
Reference Line Regulation
f
Switching Frequency
DC
MAX
Maximum Duty Cycle
I
LIM
Switch Current Limit
V
SAT
Switch V
CESAT
I
LEAK
Switch Leakage Current
The
q
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V, V
IN
= 3.3V, V
SHDN
= V
IN
, unless otherwise noted. (Notes 2, 3)
CONDITIONS
(Figure 12)
(Figure 12)
(Figure 12)
– 15V
≤
V
A
≤
15V
C
L
= 50pF (Figures 12, 16)
C
L
= 50pF (Figures 12, 16)
C
L
= 50pF (Figures 12, 16)
q
q
q
q
q
q
MIN
TYP
MAX
0.8
UNITS
V
V
V
kΩ
ns
ns
ns
V
V
nA
mA
µA
%/V
MHz
%
A
mV
µA
2
0
3
0.05
5
15
60
160
3.3
1.255
120
4.2
0.01
0.01
1.2
90
1.2
350
0.01
0.3
7
300
300
3.6
1.280
360
6
1
0.05
1.6
2
1
q
3
1.230
V
FB
= 1.255V
V
SHDN
= 2.4V, Not Switching
V
SHDN
= 0V, V
IN
= 3V
3V
≤
V
IN
≤
3.6V
q
q
q
(Note 5)
I
SW
= 900mA
V
SW
= 5V
0.85
82
1
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of the 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, C
VCC
= C
VIN
= 10µF,
C
VDD
= 1µF, C
VEE
= 3.3µF and T
A
= 25°C.
Note 4:
The Boost Regulator is specified for V
IN
= 3V unless otherwise
noted.
Note 5:
Current limit guaranteed by design and/or correlation to static test.
TYPICAL PERFOR A CE CHARACTERISTICS
V.11 Mode I
CC
vs Data Rate
170
160
150
140
I
CC
(mA)
I
CC
(mA)
140
I
CC
(mA)
135
130
125
120
50
45
40
35
30
T
A
= 25°C
130
120
110
100
90
10
100
1000
10000
2846 G04
DATA RATE (kBd)
U W
V.35 Mode I
CC
vs Data Rate
150
145
60
V.28 Mode I
CC
vs Data Rate
T
A
= 25°C
T
A
= 25°C
55
10
100
1000
DATA RATE (kBd)
10000
2846 G05
10
20
40
DATA RATE (kBd)
60
80 100
2846 G06
sn2846 2846fs
5
FPGA/CPLD
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