AD9260-EB Analog Devices, Inc., AD9260-EB Datasheet - Page 29

• Manufacturer Part Number: AD9260-EB
• Description: High-speed Oversampling Cmos Adc With 16-bit Resolution At A 2.5 Mhz Output Word Rate
• Manufacturer: Analog Devices, Inc.

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
Rev. C | Page 29 of 44
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