AD9260 Analog Devices, AD9260 Datasheet - Page 29

• Manufacturer Part Number: AD9260
• Description: 16-Bit High Speed Oversampled A/D Converter
• Manufacturer: Analog Devices

Specifications of AD9260

• Resolution (bits): 16bit
• # Chan: 1
• Sample Rate: 2.5MSPS
• Interface: Par
• Analog Input Type: Diff-Uni
• Ain Range: 4 V p-p
• Adc Architecture: Sigma-Delta
• Pkg Type: QFP

The actual reference voltages used by the internal circuitry of
the AD9260 appear on the CAPT and CAPB pins. If VREF is
configured for 2.5 V, thus providing a 4 V full-scale input span,
the voltages appear at CAPT and CAPB are 3.0 V and 1.0 V
respectively. For proper operation when using the internal or an
external reference, it is necessary to add a capacitor network to
decouple the CAPT and CAPB pins. Figure 67 shows the
recommended decoupling network. This capacitive network
performs the following three functions: (1) along with the
reference amplifier, A2, it provides a low source impedance over
a large frequency range to drive the A/D internal circuitry; (2) it
provides the necessary compensation for A2; and (3) it
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bandlimits the noise contribution from the reference. The turn-
on time of the reference voltage appearing between CAPT and
CAPB is approximately 15 ms and should be evaluated in any
power-down mode of operation.
0.1µF
Figure 67. Recommended Reference Decoupling Network
+
10µF
V
SENSE
REFCOM
REF
AD9260
CAPB
CAPT
0.1µF
+
10µF
0.1µF
0.1µF
AD9260