
M
Detailed Description
LVDS is intended for point-to-point communication over
a controlled-impedance medium as defined by the
ANSI TIA/EIA-644 and IEEE 1596.3 standards. LVDS
uses a lower voltage swing than other common com-
munication standards, achieving higher data rates with
reduced power consumption while reducing EMI emis-
sions and system susceptibility to noise.
The MAX9130 is a single LVDS line receiver ideal for
applications requiring high data rates, low power, and
low noise. The device accepts an LVDS input and
translates it to an LVTTL/LVCMOS output. The receiver
detects differential signals as low as 50mV and as high
as 1V within an input voltage range of 0 to +2.4V.
The 250mV to 450mV differential output of an LVDS dri-
ver is nominally centered around a +1.25V offset. This
offset, coupled with the receiver
’
s 0 to +2.4V input volt-
age range, allows an approximate ±1V shift in the sig-
nal (as seen by the receiver). This allows for a
difference in ground references of the driver and the
receiver, the common-mode effects of coupled noise,
or both. The LVDS standards specify an input voltage
range of 0 to +2.4V referenced to receiver ground.
Fail-Safe
The fail-safe feature of the MAX9130 sets the output
high and reduces supply current to 150μA when:
inputs are open
inputs are undriven and shorted
inputs are undriven and terminated
A fail-safe circuit is important because under these
conditions, noise at the input may switch the receiver
and it may appear to the system that data is being
received. Open or undriven terminated input conditions
can occur when a cable is disconnected or cut, or
when an LVDS driver output is in high impedance. A
short condition can occur because of a cable failure.
The fail-safe input network (Figure 1) samples the input
common-mode voltage and compares it to V
CC
- 0.3V
(nominal). When the input is driven to levels specified in
the LVDS standards, the input common-mode voltage
is less than V
CC
- 0.3V and the fail-safe circuit is not
activated. If the inputs are open or if the inputs are
undriven and shorted or undriven and parallel terminat-
ed, there is no input current. In this case, a pullup resis-
tor in the fail-safe circuit pulls both inputs above V
CC
-
0.3V, activating the fail-safe circuit and forcing the out-
put high.
Applications Information
Power-Supply Bypassing
Bypass V
CC
with a high-frequency surface-mount
ceramic 0.01μF capacitor as close to the device as
possible.
Single 500Mbps LVDS Line Receiver in SC70
6
_______________________________________________________________________________________
Pin Description
PIN
NAME
FUNCTION
1
V
CC
Power-Supply Input. Bypass V
CC
to
GND with a 0.01μF ceramic capacitor.
2, 5
3
4
6
GND
IN-
IN+
OUT
Ground
Inverting LVDS Differential Input
Noninverting LVDS Differential Input
LVTTL/LVCMOS Output
IN+
IN-
GND
OUT
MAX9130
V
CC
R
IN2
V
CC
- 0.3V
R
IN1
R
IN1
Figure 1. Fail-Safe Input Network
MAX9130
PULSE
GENERATOR
OUT
*50
REQUIRED FOR PULSE GENERATOR.
IN+
IN-
*50
*50
C
L
Rx
Figure 2. Propagation Delay and Transition Time Test Circuit