AD9233BCPZ-125 Analog Devices Inc, AD9233BCPZ-125 Datasheet - Page 27

• Manufacturer Part Number: AD9233BCPZ-125
• Description: IC ADC 12BIT 80/105/125 48-LFCSP
• Manufacturer: Analog Devices Inc

Specifications of AD9233BCPZ-125

• Data Interface: Serial, SPI™
• Number Of Bits: 12
• Sampling Rate (per Second): 125M
• Number Of Converters: 3
• Power Dissipation (max): 425mW
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 48-VFQFN, CSP Exposed Pad
• Resolution (bits): 12bit
• Sampling Rate: 125MSPS
• Input Channel Type: Differential, Single Ended
• Supply Voltage Range - Analog: 1.7V To 1.9V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: AD9233-125EBZ - BOARD EVALUATION FOR AD9233
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

LAYOUT CONSIDERATIONS
POWER AND GROUND RECOMMENDATIONS
When connecting power to the AD9233, it is recommended
that two separate supplies be used: one for analog (AVDD, 1.8 V
nominal) and one for digital (DRVDD, 1.8 V to 3.3 V nominal).
If only a single 1.8 V supply is available, then it should be routed
to AVDD first, then tapped off and isolated with a ferrite bead
or filter choke with decoupling capacitors preceding its con-
nection to DRVDD. The user can employ several different
decoupling capacitors to cover both high and low frequencies.
These should be located close to the point of entry at the PC
board level and close to the parts with minimal trace length.
A single PC board ground plane should be sufficient when
using the AD9233. With proper decoupling and smart parti-
tioning of the analog, digital, and clock sections of the board,
optimum performance is easily achieved.
Exposed Paddle Thermal Heat Slug Recommendations
It is required that the exposed paddle on the underside of the
ADC is connected to analog ground (AGND) to achieve the
best electrical and thermal performance of the AD9233. An
exposed, continuous copper plane on the PCB should mate to
the AD9233 exposed paddle, Pin 0. The copper plane should
have several vias to achieve the lowest possible resistive thermal
path for heat dissipation to flow through the bottom of the PCB.
These vias should be solder filled or plugged.
To maximize the coverage and adhesion between the ADC and
PCB, partition the continuous plane by overlaying a silkscreen
on the PCB into several uniform sections. This provides several
tie points between the two during the reflow process. Using one
continuous plane with no partitions only guarantees one tie
point between the ADC and PCB. See Figure 58 for a PCB
layout example. For detailed information on packaging and the
PCB layout of chip scale packages, see Application Note AN-772,
A Design and Manufacturing Guide for the Lead Frame Chip
Scale Package (LFCSP).
Rev. A | Page 27 of 44
CML
The CML pin should be decoupled to ground with a 0.1 μF
capacitor, as shown in Figure 38.
RBIAS
The AD9233 requires the user to place a 10 kΩ resistor between
the RBIAS pin and ground. This resister sets the master current
reference of the ADC core and should have at least a 1% tolerance.
REFERENCE DECOUPLING
The VREF pin should be externally decoupled to ground with a
low ESR 1.0 μF capacitor in parallel with a 0.1 μF ceramic low
ESR capacitor. In all reference configurations, REFT and REFB
are bypass points provided for reducing the noise contributed
by the internal reference buffer. It is recommended to place an
external 0.1 μF ceramic capacitor across REFT/REFB. While it is
not required to place this 0.1 μF capacitor, the SNR performance
will degrade by approximately 0.1 dB without it. All reference
decoupling capacitors should be placed as close to the ADC as
possible with minimal trace lengths.
SILKSCREEN PARTITION
PIN 1 INDICATOR
Figure 58. Typical PCB Layout
AD9233