LTC1544_15 Datasheet, PDF (9/20 Pages) Linear Technology – Software-Selectable Multiprotocol Transceiver

LTC1544
APPLICATIONS INFORMATION
Mode Selection
The interface protocol is selected using the mode select
pins M0, M1 and M2 (see the Mode Selection table).
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 plug-
ging 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.
The internal pull-up current sources will ensure a binary 1
when a pin is left unconnected and that the LTC1543/
LTC1544 and the LTC1344A enter the no-cable mode
when the cable is removed. In the no-cable mode the
LTC1543/LTC1544 supply current drops to less than
200µA and all LTC1543/LTC1544 driver outputs and
LTC1344A resistive terminations are forced into a high
impedance state.
The mode selection may also be accomplished by using
jumpers to connect the mode pins to ground or V_CC.
(DATA)
21
LATCH
LTC1344A
DCE/
DTE M2 M1 M0 (DATA)
22 23 24 1
CONNECTOR
M0 ¹¹
LTC1543 M1 ¹²
M2 ¹³
NC
DCE/DTE ¹⁴
NC
LTC1544
14
DCE/DTE
13
M2
12
M1
11
M0
(DATA)
CABLE
1544 F10
Figure 10: Single Port DCE V.35 Mode Selection in the Cable
9