Datasheet

MAX3172/MAX3174
+3.3V Multiprotocol Software-Selectable
Cable Terminators and Transceivers
______________________________________________________________________________________ 15
The MAX3174 does not have this glitch rejection and
can be operated at frequencies up to 240kbps if prop-
erly terminated.
DCE vs. DTE Operation
Figure 15 illustrates a DCE or DTE controller-selectable
interface. The DCE/DTE input switches the MAX3172/
MAX3174s’ mode of operation. Logic high selects DCE,
which enables driver 4 on the MAX3172/MAX3174
(INVERT = 0), driver 3 on the MAX3171/MAX3173, and
driver 3 on the MAX3170. A logic low selects DTE,
which enables receiver 4 on the MAX3172/MAX3174
(INVERT = 0), receiver 1 on the MAX3171/MAX3173,
and receiver 1 on the MAX3170.
This application requires only one DB-25 connector.
See Figure 15 for complete signal routing in DCE and
DTE modes. For example, driver 4 routes the LL(DCE)
signal to pin 18 in DCE mode, while in DTE mode,
receiver 4 routes pin 18 to the LL(DTE) signal.
Complete Multiprotocol X.21 Interface
A complete DTE-to-DCE interface operating in X.21
mode is shown in Figure 16. The MAX3172/MAX3174 ter-
minate the V.11 clock and data signals, and its transceiv-
er carries the local loopback (LL) signal. The MAX3170
carries the clock and data signals, and the
MAX3171/MAX3173 carry the control signals. The control
signals generally do not require external termination.
Compliance Testing
A European Standard EN45001 test report is available
for the MAX3170–MAX3174 chipset. A copy of the test
report is available from Maxim upon request.
R6
10kΩ
R8
5kΩ
A′
C′
A
GND
R5
30kΩ
R7
10kΩ
R4
30kΩ
MAX3172
MAX3174
S3
RECEIVER
Figure 14. V.10 Internal Resistance Networks