AD9277BSVZ Analog Devices Inc, AD9277BSVZ Datasheet - Page 40

• Manufacturer Part Number: AD9277BSVZ
• Description: IC ADC 14BIT LNA/VGA/AAF 100TQFP
• Manufacturer: Analog Devices Inc
• Type: Ultrasound Receiversr

Specifications of AD9277BSVZ

• Resolution (bits): 14 b
• Data Interface: Serial, SPI™
• Sampling Rate (per Second): 10M ~ 50M
• Voltage Supply Source: Analog and Digital
• Voltage - Supply: 1.8V, 3V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 100-TQFP Exposed Pad, 100-eTQFP, 100-HTQFP, 100-VQFP
• Sampling Rate: 50MSPS
• Input Channel Type: Single Ended
• Supply Voltage Range - Digital: 1.7V To 1.9V
• Supply Current: 365mA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

AD9277
During normal operation, CSB is used to signal to the device
that SPI commands are to be received and processed. When
CSB is brought low, the device processes SCLK and SDIO to
execute instructions. Normally, CSB remains low until the
communication cycle is complete. However, if connected to a
slow device, CSB can be brought high between bytes, allowing
older microcontrollers enough time to transfer data into shift
registers. CSB can be stalled when transferring one, two, or three
bytes of data. When W0 and W1 are set to 11, the device enters
streaming mode and continues to process data, either reading
or writing, until CSB is taken high to end the communication
cycle. This allows complete memory transfers without the need
for additional instructions. Regardless of the mode, if CSB is taken
high in the middle of a byte transfer, the SPI state machine is
reset and the device waits for a new instruction.
In addition to the operation modes, the SPI port can be
configured to operate in different manners. For applications
that do not require a control port, the CSB line can be tied and
held high. This places the remainder of the SPI pins in their
secondary mode (see the AN-877 Application Note). CSB can
also be tied low to enable 2-wire mode. When CSB is tied low,
SCLK and SDIO are the only pins required for communication.
Although the device is synchronized during power-up, caution
must be exercised when using 2-wire mode to ensure that the
serial port remains synchronized with the CSB line. When
operating in 2-wire mode, it is recommended that a 1-, 2-, or
3-byte transfer be used exclusively. Without an active CSB line,
streaming mode can be entered but not exited.
In addition to word length, the instruction phase determines
whether the serial frame is a read or write operation, allowing
the serial port to be used to both program the chip and to read
the contents of the on-chip memory. If the instruction is a read-
back operation, performing a readback causes the serial data
input/output (SDIO) pin to change direction from an input to
an output at the appropriate point in the serial frame.
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Data can be sent in MSB first mode or LSB first mode. MSB
first mode is the default at power-up and can be changed by
adjusting the configuration register. For more information
about this and other features, see the AN-877 Application Note,
Interfacing to High Speed ADCs via SPI.
HARDWARE INTERFACE
The pins described in Table 16 constitute the physical interface
between the user’s programming device and the serial port of
the AD9277. The SCLK and CSB pins function as inputs when
using the SPI. The SDIO pin is bidirectional, functioning as an
input during write phases and as an output during readback.
If multiple SDIO pins share a common connection, ensure that
proper V
pins that can be connected together and the resulting V
assuming the same load for each AD9277.
This interface is flexible enough to be controlled by either serial
PROMs or PIC microcontrollers, providing the user with
an alternative method, other than a full SPI controller, for
programming the device (see the AN-812 Application Note).
1.800
1.795
1.790
1.785
1.780
1.775
1.770
1.765
1.760
1.755
1.750
1.745
1.740
1.735
1.730
1.725
1.720
1.715
OH
0
levels are met. Figure 77 shows the number of SDIO
10
NUMBER OF SDIO PINS CONNECTED TOGETHER
20
Figure 77. SDIO Pin Loading
30
40
50
60
70
80
90
OH
100
level,