LTC2845CUHF#TR Linear Technology, LTC2845CUHF#TR Datasheet - Page 13

• Manufacturer Part Number: LTC2845CUHF#TR
• Description: IC TXRX 3.3V MULTIPROTOCOL 38QFN
• Manufacturer: Linear Technology
• Type: Transceiverr

Specifications of LTC2845CUHF#TR

• Number Of Drivers/receivers: 5/5
• Protocol: Multiprotocol
• Voltage - Supply: 3.3V
• Mounting Type: Surface Mount
• Package / Case: 38-QFN
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

APPLICATIONS
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
nected to A, ground C
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
GENERATOR
Figure 17. V.28 Receiver Configuration
B
C
A
'
'
'
Figure 16. Typical V.28 Interface
C
A
INTERCONNECTING
GND
R8
6k
S3
U
BALANCED
CABLE
20k
20k
R4
R5
'
INFORMATION
connected via the signal return
U
R6
10k
R7
10k
C
A
TERMINATION
'
'
W
CABLE
RECEIVER
LTC2845
2845 F17
LOAD
RECEIVER
U
2845 F16
'
con-
ground C is connected to a differential receiver with
ground C
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
nals (A
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
150 and the impedance between shorted terminals (A
and B) and ground C must be 150
generator termination, switches S1 and S2 are both on as
shown in Figure 20.
GENERATOR
50
50
'
B
C
A
10 , and the impedance between shorted termi-
and B
'
'
'
'
, inputs A
Figure 19. V.35 Receiver Configuration
125
R1
51.5
R2
51.5
S1
Figure 18. Typical V.35 Interface
'
S2
) and ground C
A
B
C
'
124
INTERCONNECTING
connected to A, B
R3
BALANCED
CABLE
GND
R8
6k
S3
20k
20k
R5
R4
'
must be 150
C
B
A
'
'
'
TERMINATION
R6
10k
R7
10k
'
connected to B. The
125
CABLE
LTC2845
RECEIVER
LTC2846
15 . For the
LOAD
50
50
2845 F19
sn2845 2845fs
15 .
RECEIVER
13
2845 F18
to