AD9983A/PCBZ Analog Devices Inc, AD9983A/PCBZ Datasheet - Page 40

• Manufacturer Part Number: AD9983A/PCBZ
• Description: Pb-free EVALUATION Kit AD9983A
• Manufacturer: Analog Devices Inc
• Series: Advantiv®r

Specifications of AD9983A/PCBZ

• Main Purpose: Video, Video Processing
• Embedded: No
• Utilized Ic / Part: AD9983A
• Primary Attributes: 3 x 8-Bit 140 MSPS ADC's
• Secondary Attributes: Integrated PLL & VCO
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AD9983A
OUTPUTS (BOTH DATA AND CLOCKS)
Try to minimize the trace length that the digital outputs have to
drive. Longer traces have higher capacitance and require more
instantaneous current to drive, which creates more internal
digital noise. Shorter traces reduce the possibility of reflections.
Adding a series resistor of value 50 Ω to 200 Ω can suppress
reflections, reduce EMI, and reduce the current spikes inside of
the AD9983A. If series resistors are used, place them as close to
the AD9983A pins as possible, but try not to add vias or extra
length to the output trace to get the resistors closer.
If possible, limit the capacitance that each digital output drives
to less than 10 pF. This is easily accomplished by keeping traces
short and by connecting the outputs to only one device.
Loading the outputs with excessive capacitance increases the
current transients inside of the AD9983A and creates more
digital noise on its power supplies.
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DIGITAL INPUTS
Digital inputs on the AD9983A (HSYNC0, HSYNC1, VSYNC0,
VSYNC1, SOGIN0, SOGIN1, SDA, SCL, and CLAMP) are
designed to work with 3.3 V signals, but are tolerant of 5.0 V
signals. Therefore, no extra components need to be added if
using 5.0 V logic.
Any noise that gets onto the Hsync input trace adds jitter to the
system. Therefore, minimize the trace length and do not run
any digital or other high frequency traces near it.
Reference Bypass
The AD9983A has three reference voltages that must be
bypassed for proper operation of the input PGA. REFLO and
REFHI are connected to each other through a 10 μF capacitor.
These references are used by the input PGA circuitry to assure
the greatest stability. Place them as close to the AD9983A pin as
possible. Make the ground connection as short as possible.