LTC2847CUHF Linear Technology, LTC2847CUHF Datasheet - Page 12

• Manufacturer Part Number: LTC2847CUHF
• Description: IC TXRX MULTIPROTOCOL 38-QFN
• Manufacturer: Linear Technology
• Type: Transceiverr

Specifications of LTC2847CUHF

• Number Of Drivers/receivers: 3/3
• Protocol: Multiprotocol
• Voltage - Supply: 5V
• Mounting Type: Surface Mount
• Package / Case: 38-QFN
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

APPLICATIO S I FOR ATIO
LTC2847
selected. Switching the terminations with FETs is difficult
because the FETs must remain off when the signal voltage
is beyond the supply voltage. Alternatively, custom cables
may contain termination in the cable head or route signals
to various terminations on the board.
The LTC2847/LTC2845 chip set solves the cable termina-
tion switching problem by automatically providing the
appropriate termination and switching on-chip for the
V.10 (RS423), V.11 (RS422), V.28 (RS232) and V.35
electrical protocols.
V.10 (RS423) Interface
All V.10 drivers and receivers necessary for the RS449,
EIA530, EIA530-A, V.36 and X.21 protocols are imple-
mented on the LTC2845.
A typical V.10 unbalanced interface is shown in Figure 19.
A V.10 single-ended generator with output A and ground
C is connected to a differential receiver with input A' con-
nected to A, and ground C' connected via the signal return
to 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 20.
The V.10 receiver configuration in the LTC2845 is shown
in Figure 21. In V.10 mode, switch S3 inside the LTC2845
is turned off. The noninverting input is disconnected
inside the LTC2845 receivers and connected to ground.
12
U
LTC2847
LTC2845
DCE/DTE
DCE/DTE
U
(DATA)
(DATA)
M0
M1
M2
M2
M1
M0
Figure 18. Single Port DCE V.35 Mode Selection in the Cable
W
U
CONNECTOR
–3.25mA
GENERATOR
–10V
Figure 20. V.10 Receiver Input Impedance
NC
NC
Figure 19. Typical V.10 Interface
C
A
INTERCONNECTING
BALANCED
2847 F18
–3V
CABLE
I
Z
C
A
TERMINATION
'
CABLE
'
3V
CABLE
LOAD
RECEIVER
sn2847 2847fs
10V
2847 F19
3.25mA
V
Z
2847 F20