參數(shù)資料
| 型號： | AD7725BSZ |
| 廠商： | Analog Devices Inc |
| 文件頁數(shù)： | 16/28頁 |
| 文件大小： | 0K |
| 描述： | IC ADC 16BIT PROG 44MQFP |
| 產品變化通告： | AD7725BSZ Discontinuation 16/Mar/2012 |
| 標準包裝： | 1 |
| 位數(shù)： | 16 |
| 采樣率（每秒）： | 900k |
| 數(shù)據接口： | 串行，并聯(lián) |
| 轉換器數(shù)目： | 1 |
| 功率耗散（最大）： | 30mW |
| 電壓電源： | 模擬和數(shù)字 |
| 工作溫度： | -40°C ~ 85°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 44-QFP |
| 供應商設備封裝： | 44-MQFP（10x10） |
| 包裝： | 托盤 |
| 輸入數(shù)目和類型： | 2 個單端，單極；2 個單端，雙極；1 個差分，雙極 |
| 配用： | EVAL-AD7725CBZ-ND - BOARD EVALUATION FOR AD7725 |
第1頁第2頁第3頁第4頁第5頁第6頁第7頁第8頁第9頁第10頁第11頁第12頁第13頁第14頁第15頁當前第16頁第17頁第18頁第19頁第20頁第21頁第22頁第23頁第24頁第25頁第26頁第27頁第28頁
REV. A
AD7725
–23–
Converting
To begin conversions, the RdCONV (Read Converter Data)
instruction is issued (see Table III). INT is asserted as soon as
the conversion data is ready to be read (Bit 14 of the status
register will be set). INT remains high until the digital word is
read from the device. It will then go low and return high when
the next conversion is complete. The device continues to con-
vert until the ABORT instruction is issued.
SERIAL MODE
The serial mode is selected by tying S/
P to DV
DD. Figure 4
shows the serial interface of the AD7725. The AD7725 operates
solely as a master providing two serial data input pins for the
transfer of configuration data into the device (FSI and SDI),
two serial data output pins for transfer of conversion data out of
the device (FSO and SDO), and a serial clock output (SCO).
Data is shifted in or out of the device synchronous with SCO.
The FSI and FSO signals are used to indicate to either the
device or the processor, the beginning of a word transmission
into or out of the device. The AD7725 provides the clock for
conversion and data transfers. The CFMT pin selects the active
edge of SCO during conversions and the EFMT pin selects the
active edge of SCO during configuration.
Programming the postprocessor and operating the AD7725 in
serial mode is purely pin-driven. Serial mode has three different
submodes that determine the way in which the postprocessor is to
be configured following power-up. These modes are selected by
setting the logic values on the SMODE0 and SMODE1 pins (see
Table IV). These modes are
DSP: The filter can be user defined and can be loaded from
a DSP.
EPROM: The filter can be user defined and can be loaded
from an external EPROM.
Boot from ROM (BFR): The default filter (stored in inter-
nal ROM) can be loaded into the postprocessor, which
allows the user to evaluate the device without having to load
configuration data.
In serial mode, several AD7725s can be daisy-chained together
so they can all be configured from one EPROM or DSP and
conversion data from all devices can be read back by one DSP.
DSP Mode–Loading Configuration Data from a DSP
In this mode, a user-defined filter can be developed and the
resulting configuration file loaded into the postprocessor from a
DSP. The DSP therefore loads data into the AD7725 and reads
back the conversion results. This mode of operation is selected by
tying SMODE0 to DVDD and SMODE1 to DGND. The values
on these pins inform the AD7725 that user-defined filter data is
to be loaded into the postprocessor from the DSP automatically
following power-up. The data is loaded using FSI and SDI and
the transfer of data is controlled by SCO. During the download
of configuration data, SCO = fCLKIN/16. Following power-on
reset, the
SOE pin goes high to inform the DSP that configura-
tion of the postprocessor can begin. If no errors occur during the
configuration, the CFGEND output will go high. In Figure 26,
the CFGEND is tied to INIT, thus it will drive INIT high, and the
part will begin converting. However, if an error does occur during
the configuration, the
ERR bit will go low, and CFGEND will not
go high. The INIT pin will therefore not start conversions. The
part will not do anything until
RESETCFG is pulsed low. When
this occurs, the part is reset,
SOE goes high, and the configuration
file is reloaded.
The AD7725 will read the entire configuration file, and, if an
error does occur during configuration, the user will be notified
only once the whole file has been read. In this case, the data will
not be loaded into the postprocessor. After data has been down-
loaded, the serial clock frequency (SCO) is selected by the value
on SCR and can be CLKIN (SCR = 0) or CLKIN/2 (SCR = 1).
SCO must have a frequency equal to CLKIN if the AD7725
outputs data at CLKIN/16. For lower output word rates, either
clock frequency can be used. To load configuration data into
the AD7725, an FSI pulse one CLKIN cycle wide informs the
AD7725 that data is being transferred into the device. The data
is loaded using the next 16 SCLK cycles following the detection
of the FSI pulse. Figure 26 shows the connection diagram for
the AD7725 when loading configuration data from a DSP, and
Figure 27 shows a flow chart of the power-up and configura-
tion sequence.
DVDD
SOE
ERR
DVAL
S/
P
INIT
RESETCFG
CFGEND
SMODE1
SYNC
SCO
FSO
SDO
SDI
FSI
AD7725
SCLK0
RFS0
DR0
DT0
TFS0
ADSP-21xx
SMODE0
INT
DVDD
Figure 26. Connection Diagram for Loading the
Filter Configuration Data from a DSP
POWER-ON RESET
IMMEDIATE BOOT
FROM A DSP
USER-DEFINED FILTER
DATA LOADED INTO
THE POSTPROCESSOR
FROM A DSP
CFGEND = 1
INIT = 1
DEVICE STARTS
CONVERTING
SMODE0 = 1
SMODE1 = 0
DATA
LOADED
CORRECTLY?
PULSE
RESETCFG
LOW
NO
YES
ERR = 0
SOE GOES HIGH
Figure 27. Flow Chart of DSP Mode
相關PDF資料 |
PDF描述 |
|---|---|
| AD7730BN | IC ADC TRANSDUCER BRIDGE 24-DIP |
| AD7731BN | IC ADC 24BIT SIGMA-DELTA 24-DIP |
| AD7732BRU | IC ADC 24BIT 2-CH 28-TSSOP |
| AD7734BRU | IC ADC 24BIT 4-CH 28-TSSOP |
| AD7738BRU | IC ADC 24BIT 8-CH 28-TSSOP |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| AD7727BCPZRL | 制造商:Analog Devices 功能描述: |
| AD7728ARU | 制造商:Analog Devices 功能描述: |
| AD7729 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Dual Sigma-Delta ADC with Auxiliary DAC |
| AD7729AR | 制造商:Analog Devices 功能描述:ADC Dual Delta-Sigma 13Msps 15-bit Serial 28-Pin SOIC W 制造商:Rochester Electronics LLC 功能描述:3DUAL SIGMA DELTA ADC I.C. - Bulk 制造商:Analog Devices 功能描述:ADC DUAL SIGMA DELTA 7729 SOIC28 |
| AD7729AR-REEL7 | 制造商:Analog Devices 功能描述:ADC Dual Delta-Sigma 13Msps 15-bit Serial 28-Pin SOIC W T/R |
發(fā)布緊急采購，3分鐘左右您將得到回復。