MAX13171E Datasheet, PDF (26/38 Pages) Maxim Integrated Products – Multiprotocol, Pin-Selectable Data Interface Chipset

Multiprotocol, Pin-Selectable
Data Interface Chipset
No-Cable Mode
The MAX13171E/MAX13173E enter no-cable mode
when the mode-select inputs are left unconnected or
connected high (M0 = M1 = M2 = 1). The receiver out-
puts enter a high-impedance state in no-cable mode,
allowing these output lines to be shared with other
receiver outputs (the receiver outputs have an internal
pullup resistor to pull the outputs high if not driven).
Also, in no-cable mode, the transmitter outputs enter a
high-impedance state, so these output lines can be
shared with other devices.
The MAX13175E enters no-cable mode when the mode
select inputs, M0, M1, and M2 are connected high. In
no-cable mode, all six termination networks are placed
in V.11 mode, with S1 closed and S2 open.
V_L Logic Supply
The MAX13171E/MAX13173E/MAX13175E include a V_L
logic supply that allows user-defined interface logic-
voltage levels referenced to V_L. V_L can go down to
+1.62V and up to V_CC. All logic inputs and outputs are
referred to V_L.
Data Rate
The MAX13171E/MAX13173E/MAX13175E support a
maximum data rate of 40Mbps in RS-449/V.36, RS-530,
RS-530A, X.21, V.35 if only one of the MAX13171E
high-speed transceivers is operated at the maximum
data rate. If two high-speed transceivers operate simul-
taneously, the maximum data rate is 20Mbps.
Applications Information
Capacitor Selection
The capacitors used for the charge pumps, as well as
for supply bypassing, must have a low equivalent
series resistance (ESR), low inductance (ESL), and low
temperature coefficient. Multilayer ceramic capacitors
with an X7R dielectric offer the best combination of per-
formance, size, and cost. The flying capacitors (C1, C2)
should have a value of 1µF, while the bypass capacitor
(C4) and reservoir capacitors (C3, C5) should have a
minimum value of 4.7µF (Figure 15). To reduce the rip-
ple present on the transmitter outputs, capacitors C3,
C4, and C5 can be increased. The values of C1 and C2
should not be increased.
Cable Mode-Select Application
A cable-selectable multiprotocol interface is shown in
Figure 17. The mode control lines M0, M1, and DCE/DTE
are wired to the DB-25 connector. To select the serial
interface mode, the appropriate combination of M0, M1,
and DCE/DTE are grounded within the cable wiring. The
control lines that are not grounded are pulled high by the
internal pullups on the MAX13171E/MAX13173E. The
serial interface protocol of the MAX13171E/
MAX13173E/MAX13175E is selected based on the cable
that is connected to the DB-25 interface.
V.10 (RS-423) Interface
(MAX13173E Only)
The V.10 interface (Figure 18) is an unbalanced single-
ended interface capable of driving a 450Ω load. The
V.10 driver generates a minimum V_O voltage of ±4V
across A’ and C’ when unloaded, and a minimum volt-
age of 0.9 x V_O when loaded with 450Ω. The V.10
receiver has a single-ended input and does not reject
common-mode differences between C and C’. The V.10
receiver-input trip threshold is defined between +50mV
and +250mV with input impedance characteristic
shown in Figure 19.
The MAX13173E V.10 mode receiver has a threshold
between +50mV and +250mV. To ensure that the
receiver has proper fail-safe operation, see the Fail-
Safe section. To aid in rejecting system noise, the
MAX13173E V.10 receiver has a typical hysteresis of
25mV. Switch S3 in Figures 20a and 20b is open in
V.10 mode to disable the V.28 5kΩ termination at the
receiver input. Switch S4 is closed and switch S5 is
open to internally ground the receiver B input.
26 ______________________________________________________________________________________