AD9287 Analog Devices, AD9287 Datasheet - Page 36

• Manufacturer Part Number: AD9287
• Description: Quad, 8-Bit, 100 MSPS Serial LVDS 1.8 V A/D Converter
• Manufacturer: Analog Devices

Specifications of AD9287

• Resolution (bits): 8bit
• # Chan: 4
• Sample Rate: 100MSPS
• Interface: LVDS,Ser
• Analog Input Type: Diff-Uni
• Ain Range: 2 V p-p
• Adc Architecture: Pipelined
• Pkg Type: CSP

AD9287
DEFAULT OPERATION AND JUMPER SELECTION
SETTINGS
The following is a list of the default and optional settings or
modes allowed on the AD9287 Rev. A evaluation board.
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POWER: Connect the switching power supply that is
provided with the evaluation kit between a rated 100 V ac
to 240 V ac wall outlet at 47 Hz to 63 Hz and P503.
AIN: The evaluation board is set up for a transformer-
coupled analog input with an optimum 50 Ω impedance
match of 190 MHz of bandwidth (see Figure 61). For more
bandwidth response, the differential capacitor across the
analog inputs can be changed or removed. The common
mode of the analog inputs is developed from the center tap
of the transformer or AVDD_DUT/2.
VREF: VREF is set to 1.0 V by tying the SENSE pin to ground,
R237. This causes the ADC to operate in 2.0 V p-p full-scale
range. A separate external reference option using the ADR510
is also included on the evaluation board. Populate R231 and
R235 and remove C214. Proper use of the VREF options is
noted in the Voltage Reference section.
RBIAS: RBIAS has a default setting of 10 kΩ (R201) to
ground and is used to set the ADC core bias current.
CLOCK: The default clock input circuitry is derived from a
simple transformer-coupled circuit using a high bandwidth
1:1 impedance ratio transformer (T201) that adds a very
low amount of jitter to the clock path. The clock input is
50 Ω terminated and ac-coupled to handle single-ended
sine wave types of inputs. The transformer converts the
single-ended input to a differential signal that is clipped
before entering the ADC clock inputs.
–10
–12
–14
–16
–2
–4
–6
–8
0
0
Figure 61. Evaluation Board Full-Power Bandwidth
50
100
150
FREQUENCY (MHz)
200
–3dB CUTOFF = 190MHz
250
300
350
400
450
500
Rev. E | Page 36 of 52
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A differential LVPECL clock can also be used to clock the
ADC input using the AD9515 (U202). Populate R225 and
R227 with 0 Ω resistors and remove R217 and R218 to
disconnect the default clock path inputs. In addition, populate
C207 and C208 with a 0.1 μF capacitor and remove C210 and
C211 to disconnect the default clock path outputs. The
AD9515 has many pin-strappable options that are set to a
default mode of operation. Consult the AD9515 data sheet
for more information about these and other options.
and can act as the primary clock source. The setup is quick
and involves installing R212 with a 0 Ω resistor and setting
the enable jumper (J205) to the on position. If the user wishes
to employ a different oscillator, two oscillator footprint options
are available (OSC201) to check the ADC performance.
PDWN: To enable the power-down feature, short J201 to
AVDD on the PDWN pin.
SCLK/DTP: To enable the digital test patterns on the digital
outputs of the ADC, use J204. If J204 is tied to AVDD during
device power-up, Test Pattern 1000 0000 is enabled. See the
SCLK/DTP Pin section for details.
SDIO/ODM: To enable the low power, reduced signal option
(similar to the IEEE 1595.3 reduced range link LVDS output
standard), use J203. If J203 is tied to AVDD during device
power-up, it enables the LVDS outputs in a low power,
reduced signal option from the default ANSI-644 standard.
This option changes the signal swing from 350 mV p-p to
200 mV p-p, reducing the power of the DRVDD supply. See
the SDIO/ODM Pin section for more details.
CSB: To enable processing of the SPI information on the SDIO
and SCLK pins, tie J202 low in the always enable mode. To
ignore the SDIO and SCLK information, tie J202 to AVDD.
Non-SPI Mode: For users who wish to operate the DUT
without using SPI, remove Jumpers J202, J203, and J204.
This disconnects the CSB, SCLK/DTP, and SDIO/ODM pins
from the control bus, allowing the DUT to operate in its
simplest mode. Each of these pins has internal termination
and will float to its respective level.
D + x, D − x: If an alternative data capture method to the setup
shown in Figure 60 is used, optional receiver terminations,
R206 to R211, can be installed next to the high speed back-
plane connector.
In addition, an on-board oscillator is available on the OSC201
Data Sheet