AD9248 Analog Devices, AD9248 Datasheet - Page 35

• Manufacturer Part Number: AD9248
• Description: Dual 14-Bit, 20/40/65 MSPS, 3 V Analog-to-Digital Converter
• Manufacturer: Analog Devices

Specifications of AD9248

• Resolution (bits): 14bit
• # Chan: 2
• Sample Rate: 65MSPS
• Interface: Par
• Analog Input Type: Diff-Uni,SE-Uni
• Ain Range: 1 V p-p,2 V p-p,Uni 1.0V,Uni 2.0V
• Adc Architecture: Pipelined
• Pkg Type: QFP

DUAL ADC LFCSP PCB
The PCB requires a low jitter clock source, analog sources, and
power supplies. The PCB interfaces directly with Analog Devices
standard dual-channel data capture board (HSC-ADC-EVAL-DC),
which together with ADI’s ADC Analyzer™ software allows for
quick ADC evaluation.
POWER CONNECTOR
Power is supplied to the board via three detachable 4-lead
power strips.
Table 11. Power Connector
Terminal
VCC
VDD
VDL
VREF
+5 V
−5 V
1
ANALOG INPUTS
The evaluation board accepts a 2 V p-p analog input signal
centered at ground at two SMB connectors, Input A and
Input B. These signals are terminated at their respective
transformer primary side. T1 and T2 are wideband RF
transformers that provide the single-ended-to-differential
conversion, allowing the ADC to be driven differentially,
minimizing even-order harmonics. The analog signals can be
low-pass filtered at the transformer secondary to reduce high
frequency aliasing.
OPTIONAL OPERATIONAL AMPLIFIER
The PCB has been designed to accommodate an optional
AD8139 op amp that can serve as a convenient solution for
dc-coupled applications. To use the AD8139 op amp, remove
C14, R4, R5, C13, R37, and R36. Place R22, R23, R30, and R24.
VCC, VDD, and VDL are the minimum required power connections.
1
1
1
3.0 V
3.0 V
3.0 V
Comments
Analog supply for ADC
Output supply for ADC
Supply circuitry
Optional external VREF
Optional op amp supply
Optional op amp supply
Rev. B | Page 35 of 48
CLOCK
The clock inputs are buffered on the board at U5 and U6. These
gates provide buffered clocks to the on-board latches, U2 and
U4, ADC input clocks, and DRA, DRB that are available at the
output Connector P3, P8. The clocks can be inverted at the
timing jumpers labeled with the respective clocks. The clock
paths also provide for various termination options. The ADC
input clocks can be set to bypass the buffers at solder bridges
P2, P9 and P10, P12. An optional clock buffer U3, U7 can also
be placed. The clock inputs can be bridged at TIEA, TIEB (R20,
R40) to allow one to clock both channels from one clock source;
however, optimal performance is obtained by driving J2 and J3.
Table 12. Jumpers
Terminal
OEB A
PDWN A
MUX
SHARED REF
DR A
LATA
ENC A
OEB B
PDWN B
DFS
SHARED REF
DR B
LATB
ENC B
VOLTAGE REFERENCE
The ADC SENSE pin is brought out to E41, and the internal
reference mode is selected by placing a jumper from E41 to
ground (E27). External reference mode is selected by placing a
jumper from E41 to E25 and E30 to E2. R56 and R45 allow for
programmable reference mode selection.
DATA OUTPUTS
The ADC outputs are latched on the PCB at U2, U4. The ADC
outputs have the recommended series resistors in line to limit
switching transient effects on ADC performance.
Comments
Output Enable for A Side
Power-Down A
Mux Input
Shared Reference Input
Invert DR A
Invert A Latch Clock
Invert Encode A
Output Enable for B Side
Power-Down B
Data Format Select
Shared Reference Input
Invert DR B
Invert B Latch Clock
Invert Encode B
AD9248