MAX9311/MAX9313
1:10 Differential LVPECL/LVECL/HSTL
Clock and Data Drivers
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Detailed Description
The MAX9311/MAX9313 are low skew, 1-to-10 differential drivers designed for clock and data distribution.
A 2:1 mux selects between the two differential inputs,
CLK0, CLK0 and CLK1, CLK1. The 2:1 mux is switched
by the single-ended CLKSEL input. A logic low selects
the CLK0, CLK0 input. A logic high selects the CLK1,
CLK1 input. The logic threshold for CLKSEL is set by an
internal VBBvoltage reference. The CLKSEL input can
be driven to VCCand VEEor by a single-ended LVPECL/
LVECL signal. The selected input is reproduced at 10
differential outputs.
For interfacing to differential HSTL and LVPECL signals,
these devices operate over a +2.25V to +3.8V supply
range, allowing high-performance clock or data distribution in systems with a nominal +2.5V or +3.3V supply.
For differential LVECL operation, these devices operate
from a -2.25V to -3.8V supply.
The differential inputs can be configured to accept single-ended inputs when operating at approximately VCCVEE= +3.0V to +3.8V for the MAX9311 or VCC- VEE=
+2.7V to +3.8V for the MAX9313. This is accomplished
by connecting the on-chip reference voltage, VBB, to an
input as a reference. For example, the differential CLK0,
CLK0 input is converted to a noninverting, single-ended
input by connecting VBBto CLK0 and connecting the
single-ended input to CLK0. Similarly, an inverting input
is obtained by connecting VBBto CLK0 and connecting
the single-ended input to CLK0. With a differential input
configured as single-ended (using VBB), the singleended input can be driven to VCCand VEEor with a single-ended LVPECL/LVECL signal.
When a differential input is configured as a single-ended
input (using VBB), the approximate supply range is VCCVEE= +3.0V to +3.8V for the MAX9311 and VCC- VEE=
+2.7V to +3.8V for the MAX9313. This is because one of
the inputs must be VEE+ 1.2V or higher for proper operation of the input stage. VBBmust be at least VEE+ 1.2V
because it becomes the high-level input when the other
(single-ended) input swings below it. Therefore, minimum VBB= VEE+ 1.2V.
The minimum V
BB
output for the MAX9311 is VCC-
1.525V and the minimum VBBoutput for the MAX9313 is
VCC- 1.38V. Substituting the minimum VBBoutput for
each device into VBB= VEE+ 1.2V results in a minimum
supply of 2.725V for the MAX9311 and 2.58V for the
MAX9313. Rounding up to standard supplies gives the
single-ended operating supply ranges of VCC- VEE=
3.0V to 3.8V for the MAX9311 and VCC- VEE= 2.7V to
3.8V for the MAX9313.
When using the V
BB
reference output, bypass it with a
0.01µF ceramic capacitor to VCC. If the VBBreference is
not used, it can be left open. The VBBreference can
source or sink 0.5mA, which is sufficient to drive two
inputs. Use VBBonly for inputs that are on the same
device as the VBBreference.
The maximum magnitude of the differential input from
CLK_ to CLK_ is 3.0V or VCC- VEE, whichever is less.
This limit also applies to the difference between any reference voltage input and a single-ended input.
The differential inputs have bias resistors that drive the
outputs to a differential low when the inputs are open.
The inverting inputs (CLK0 and CLK1) are biased with a
75kΩ pullup to VCCand a 75kΩ pulldown to VEE. The
noninverting inputs (CLK0 and CLK1) are biased with a
75kΩ pulldown to V
EE
. The single-ended CLKSEL input
does not have a bias resistor. If not driven, pull CLKSEL
up or down with a 1kHz resistor (see Pin Description).
Specifications for the high and low voltages of a differential input (V
IHD
and V
ILD
) and the differential input volt-
age (V
IHD
- V
ILD
) apply simultaneously (V
ILD
cannot be
higher than V
IHD
).
Output levels are referenced to VCCand are considered
LVPECL or LVECL, depending on the level of the V
CC
supply. With VCCconnected to a positive supply and
V
EE
connected to GND, the outputs are LVPECL. The
outputs are LVECL when VCCis connected to GND and
V
EE
is connected to a negative supply.
A single-ended input of at least VBB±95mV or a differential input of at least 95mV switches the outputs to the
V
OH
and VOLlevels specified in the DC Electrical
Characteristics table.
Applications Information
Supply Bypassing
Bypass VCCto VEEwith high-frequency surface-mount
ceramic 0.1µF and 0.01µF capacitors in parallel as close
to the device as possible, with the 0.01µF value capacitor closest to the device. Use multiple parallel vias for
low inductance. When using the VBBreference output,
bypass it with a 0.01µF ceramic capacitor to VCC(if the
VBBreference is not used, it can be left open).
Traces
Input and output trace characteristics affect the performance of the MAX9311/MAX9313. Connect each signal
of a differential input or output to a 50Ω characteristic
impedance trace. Minimize the number of vias to prevent
impedance discontinuities. Reduce reflections by maintaining the 50Ω characteristic impedance through connectors and across cables. Reduce skew within a