ADC14V155LFEB/NOPB National Semiconductor, ADC14V155LFEB/NOPB Datasheet - Page 19

• Manufacturer Part Number: ADC14V155LFEB/NOPB
• Description: BOARD EVAL ADC14V155LF
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of ADC14V155LFEB/NOPB

• Number Of Adc's: 1
• Number Of Bits: 14
• Sampling Rate (per Second): 155M
• Data Interface: Parallel
• Inputs Per Adc: 1 Differential
• Power (typ) @ Conditions: 951mW @ 155MSPS
• Voltage Supply Source: Analog and Digital
• Operating Temperature: -40°C ~ 85°C
• Utilized Ic / Part: ADC14V155
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: ADC14V155LFEB

4.0 DIGITAL OUTPUTS
Digital outputs consist of the LVDS signals D0-D13, DRDY
and OVR.
The ADC14V155 has 16 LVDS compatible data output pins:
14 data output bits corresponding to the converted input val-
ue, a data ready (DRDY) signal that should be used to capture
the output data and an over-range indicator (OVR) which is
set high when the sample amplitude exceeds the 14-Bit con-
version range. Valid data is present at these outputs while the
PD/Sleep pin is low.
The odd data bits should be captured with the falling edge of
DRDY and the even data bits should be captured with the
rising edge of DRDY.
Be very careful when driving a high capacitance bus. The
more capacitance the output drivers must charge for each
conversion, the more instantaneous digital current flows
19
through V
spikes can cause on-chip ground noise and couple into the
analog circuitry, degrading dynamic performance. Adequate
bypassing, limiting output capacitance and careful attention
to the ground plane will reduce this problem. Additionally, bus
capacitance beyond the specified 5 pF/pin will cause t
increase, reducing the setup and hold time of the ADC output
data. The result could be an apparent reduction in dynamic
performance.
To minimize noise due to output switching, the load currents
at the digital outputs should be minimized. This can be
achieved by keeping the PCB traces less than 2 inches long;
longer traces are more susceptible to noise. Try to place the
100 ohm termination resistor as close to the receiving circuit
as possible. See Figure 4.
DR
and DRGND. These large charging current
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to