MAX9174 Maxim, MAX9174 Datasheet - Page 8

• Manufacturer Part Number: MAX9174
• Description: The MAX9174/MAX9175 are 670MHz, low-jitter, low-skew 1:2 splitters ideal for protection switching, loopback, and clock and signal distribution
• Manufacturer: Maxim

When the input is driven with a differential signal of |V
= 50mV to 1.2V within a voltage range of 0 to 2.4V, the
fail-safe circuit is not activated. If the input is open,
undriven and shorted, or undriven and terminated, an
internal resistor in the fail-safe circuit pulls the input
above VCC - 0.3V, activating the fail-safe circuit and
forcing the outputs high (Figure 1).
The MAX9174/MAX9175 are designed to protect the
power-down inputs (PD0 and PD1) against latchup due
to transient overshoot and undershoot voltage. If the
input voltage goes above VCC or below GND by up to
1V, an internal circuit limits input current to 1.5mA.
Bypass the V
ceramic 0.1µF and 0.001µF capacitors in parallel as
close to the device as possible, with the smaller valued
capacitor closest to V
Input and output trace characteristics affect the perfor-
mance of the MAX9174/MAX9175. Use controlled-
impedance differential traces (100Ω typ). To reduce
radiated noise and ensure that noise couples as com-
mon mode, route the differential input and output sig-
nals within a pair close together. Reduce skew by
matching the electrical length of the two signal paths
that make up the differential pair. Excessive skew can
result in a degradation of magnetic field cancellation.
Maintain a constant distance between the differential
traces to avoid discontinuities in differential impedance.
Minimize the number of vias to further prevent imped-
ance discontinuities.
Interconnect for LVDS typically has a controlled differ-
ential impedance of 100Ω. Use cables and connectors
that have matched differential impedance to minimize
impedance discontinuities.
Avoid the use of unbalanced cables such as ribbon or
simple coaxial cable. Balanced cables such as twisted
pair offer superior signal quality and tend to generate
less EMI due to magnetic field canceling effects.
Balanced cables pick up noise as common mode,
which is rejected by the LVDS receiver.
The MAX9174/MAX9175 require external input and out-
put termination resistors. For LVDS, connect an input
670MHz LVDS-to-LVDS and Anything-to-LVDS
1:2 Splitters
8
_______________________________________________________________________________________
Overshoot and Undershoot Voltage
CC
Applications Information
pin with high-frequency surface-mount
CC
Power-Supply Bypassing
.
Cables and Connectors
Differential Traces
Termination
Protection
ID
|
termination resistor across the differential input and at
the far end of the interconnect driven by the LVDS out-
puts. Place the input termination resistor as close to the
receiver input as possible. Termination resistors should
match the differential impedance of the transmission
line. Use 1% surface-mount resistors.
Table 1. Input Function Table
Table 2. Power-Down Function Table
Figure 1. Input Structure
L or open
L or open
MAX9175
MAX9174
High
P P P P D D D D 1 1 1 1
IN+
IN-
R
R
H
IN1
IN1
-50mV < VID < +50mV
MAX9174 INTERNAL FAIL-SAFE CIRCUIT
(IN+) - (IN-)
V
CC
INPUT
L or open
L or open
+50mV
R
-50mV
parallel termination
IN2
short, or undriven
V
High
P P P P D D D D 0 0 0 0
Open, undriven
CC
H
- 0.3V
COMPARATOR
Open
DIFFERENTIAL
RCVR
Both outputs enabled
Shutdown to minimum power,
outputs high impedance to ground
OUT0 enabled, OUT1 high
impedance to ground
OUT1 enabled, OUT0 high
impedance to ground
TO
OUTPUT
OUT_+, OUT_-
(OUT_+) - (OUT_-)
Indeterminate
IN+
IN-
OUTPUTS
MAX9175 INPUT
V
CC
H
H
L
R
R
IN3
IN3