AD9481 datasheet(23/29 Pages) AD

23 / 29 page

AD9481

Rev. 0 | Page 22 of 28

OPTIONAL XTAL

The PCB has been designed to accommodate an optional

crystal oscillator that can serve as a convenient clock source.

The footprint can accept both through-hole and surface-mount

devices, including Vectron XO-400 and Vectron VCC6 family

oscillators.

VCC

OUT–

OUT+

GND

Figure 38. XTAL Footprint

To use either crystal, populate C38 and C40 with 0.1 µF capaci-

tors. Populate R48 and R49 with 0 Ω resistors. Place R50, R51,

R59, and R60 with 1 kΩ resistors. Remove C6 and C5. If the

Vectron VCC6 family crystal is being used, populate R57 with a

10 Ω resistor. If using the XO-400 crystal, place jumper E21 or

E22 to E23.

VOLTAGE REFERENCE

The AD9481 has an internal 1 V reference mode. The ADC uses

the internal 1 V reference as the default when sense is set to

ground. An optional on-board external 1.0 V reference

(ADR510) can be used by setting the sense jumper to AVDD, by

placing a jumper on E5 to E3, and by placing a 0 Ω resistor on

R55. When using an external programmable reference, (R20,

R30) remove the sense jumper.

DATA OUTPUTS

The ADC outputs are buffered on the PCB by LVT574 latches

on the data outputs. The latch outputs have series terminating

resistors at the output pins to minimize reflections.

AD9481 Datasheet(PDF) 23 Page - Analog Devices