ADC122S706EB/NOPB National Semiconductor, ADC122S706EB/NOPB Datasheet - Page 22

• Manufacturer Part Number: ADC122S706EB/NOPB
• Description: BOARD EVAL FOR ADC122S706
• Manufacturer: National Semiconductor

Specifications of ADC122S706EB/NOPB

• Number Of Adc's: 2
• Number Of Bits: 12
• Sampling Rate (per Second): 1M
• Data Interface: Serial
• Inputs Per Adc: 1 Differential
• Input Range: ±VREF
• Power (typ) @ Conditions: 25mW @ 1MSPS
• Voltage Supply Source: Analog and Digital
• Operating Temperature: -40°C ~ 105°C
• Utilized Ic / Part: ADC122S706
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: ADC122S706EB

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6.3 Bridge Sensor Application
Figure 14 shows an example of interfacing the ADC122S706
to a pair of bridge sensors. The application assumes that the
bridge sensors require buffering and amplification to fully uti-
lize the dynamic range of the ADC and thus optimize the
performance of the entire signal path. The amplification stage
for each ADC input consists of a pair of opamps from the
LMP7704. The amplification stage offers the benefit of high
input impedance and potentially high amplification. On the
FIGURE 14. Interfacing the ADC122S706 to Bridge Sensors
22
other hand, it offers no common-mode rejection of noise com-
ing from the bridge sensors. The application circuit assumes
the bridge sensors are powered from the same +5V power
supply voltage as the analog supply pin on the ADC122S706.
This has the benefit of providing the ideal common-mode in-
put voltage for the ADC122S706 while keeping design com-
plexity and cost to a minimum. The LM4132-4.1, a 4.1V series
reference, is used as the reference voltage in the application.
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