- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄17030 > EVAL-AD7730LEBZ (Analog Devices Inc)BOARD EVALUATION FOR AD7730 PDF資料下載
參數(shù)資料
| 型號(hào)： | EVAL-AD7730LEBZ |
| 廠商： | Analog Devices Inc |
| 文件頁數(shù)： | 36/53頁 |
| 文件大?。?/td> | 0K |
| 描述： | BOARD EVALUATION FOR AD7730 |
| 標(biāo)準(zhǔn)包裝： | 1 |
| ADC 的數(shù)量： | 1 |
| 位數(shù)： | 24 |
| 采樣率（每秒）： | 600 |
| 數(shù)據(jù)接口： | 串行 |
| 輸入范圍： | ±80 mV |
| 在以下條件下的電源（標(biāo)準(zhǔn)）： | 125mW @ 600SPS |
| 工作溫度： | -40°C ~ 85°C |
| 已用 IC / 零件： | AD7730 |
| 已供物品： | 板，CD |
| 相關(guān)產(chǎn)品： | AD7730LBRUZ-ND - IC ADC TRANSDUCER BRIDGE 24TSSOP AD7730LBRZ-ND - IC ADC TRANSDUCER BRIDGE 24SOIC AD7730LBRUZ-REEL7-ND - IC ADC TRANSDUCER BRIDGE 24TSSOP AD7730LBRZ-REEL-ND - IC ADC TRANSDUCER BRIDGE 24SOIC AD7730LBRUZ-REEL-ND - IC ADC TRANSDUCER BRIDGE 24TSSOP AD7730BRUZ-REEL7-ND - IC ADC BRIDGE TRANSDUCER 24TSSOP AD7730BRUZ-REEL-ND - IC ADC BRIDGE TRANSDUCER 24TSSOP AD7730BRUZ-ND - IC ADC TRANSDUCER BRIDGE 24TSSOP AD7730BNZ-ND - IC ADC TRANSDUCER BRIDGE 24-DIP AD7730BRZ-REEL7TR-ND - IC ADC BRDGE TRANSDCR 24SOIC TR 更多... |
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頁第29頁第30頁第31頁第32頁第33頁第34頁第35頁當(dāng)前第36頁第37頁第38頁第39頁第40頁第41頁第42頁第43頁第44頁第45頁第46頁第47頁第48頁第49頁第50頁第51頁第52頁第53頁
AD7730/AD7730L
–41–
Long lead lengths from the bridge to the AD7730 facilitate the
pickup of mains frequency on the analog input, the reference
input and the power supply. The analog inputs to the AD7730
are buffered, which allows the user to connect whatever noise
reduction capacitors are necessary in the application. The AD7730
boasts excellent common-mode and normal- mode rejection of
mains frequency on both the analog and reference inputs. In
CHOP mode, care must be taken in choosing the output update
rate so it does not result in reducing line frequency rejection
(see DIGITAL FILTERING section). The input offset current
on the AD7730 is 10 nA maximum which results in a maxi-
mum, dc offset voltage of 1.75 mV in a 350
Ω bridge applica-
tion. Care should taken with inserting large source impedances
on the reference input pins as these inputs are not buffered and
the source impedances can result in gain errors.
In many load-cell applications, a portion of the dynamic range
of the bridge output is consumed by a pan weight or tare weight.
In such applications, the 6-bit TARE DAC of the AD7730 can
be used to adjust out this tare weight as outlined previously.
AC Excitation of Bridge
AC excitation of the bridge addresses many of the concerns with
thermocouple, offset and drift effects encountered in dc-excited
applications. In ac-excitation, the polarity of the excitation volt-
age to the bridge is reversed on alternate cycles. The result is the
elimination of dc errors at the expense of a more complex sys-
tem design. Figure 24 outlines the connections for an ac-excited
bridge application based on the AD7730.
The excitation voltage to the bridge must be switched on
alternate cycles. Transistors T1 to T4 in Figure 24 perform
the switching of the excitation voltage. These transistors can be
discrete matched bipolar or MOS transistors, or a dedicated
bridge driver chip such as the 4427 from Micrel can be used to
perform the task.
Since the analog input voltage and the reference voltage are
reversed on alternate cycles, the AD7730 must be synchronized
with this reversing of the excitation voltage. To allow the
AD7730 to synchronize itself with this switching, it provides the
logic control signals for the switching of the excitation voltage.
These signals are the nonoverlapping CMOS outputs ACX
and
ACX.
One of the problems encountered with ac-excitation is the set-
tling time associated with the analog input signals after the
excitation voltage is switched. This is particularly true in appli-
cations where there are long lead lengths from the bridge to the
AD7730. It means that the converter could encounter errors
because it is processing signals which are not fully settled. The
AD7730 addresses this problem by allowing the user to program
a delay of up to 48.75
μs between the switching of the ACX
signals and the processing of data at the analog inputs. This is
achieved using the DL bits of the Filter Register.
The AD7730 also scales the ACX switching frequency in accor-
dance with the output update rate. This avoids situations where
the bridge is switched at an unnecessarily faster rate than the
system requires.
The fact that the AD7730 can handle reference voltages which
are the same as the excitation voltages is particularly useful in
ac-excitation where resistor divider arrangements on the
reference input add to the settling time associated with the
switching.
Figure 24. Typical Connections for AC-Excited Bridge Application
SIGMA-
DELTA
MODULATOR
AVDD
DVDD
AD7730
6-BIT
DAC
SERIAL INTERFACE
AND CONTROL LOGIC
REGISTER BANK
CLOCK
GENERATION
PROGRAMMABLE
DIGITAL
FILTER
SIGMA-DELTA A/D CONVERTER
BUFFER
PGA
AIN2(+)/D1
AIN2(–)/D0
ACX
STANDBY
SYNC
MCLK IN
MCLK OUT
SCLK
CS
DIN
DOUT
RESET
RDY
POL
DGND
AGND
MUX
AC
EXCITATION
CLOCK
CALIBRATION
MICROCONTROLLER
+
IN+
OUT–
IN–
OUT+
REF IN(+)
REF IN(–)
AIN1(+)
AIN1(–)
EXCITATION VOLTAGE = +5V
T4
T3
T2
T1
+/–
REV. B
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| EBC20DRTN-S93 | CONN EDGECARD 40POS DIP .100 SLD |
| RGM06DTKN-S288 | CONN EDGECARD 12POS .156 EXTEND |
| EBC20DRTH-S93 | CONN EDGECARD 40POS DIP .100 SLD |
| PCMC133E-1R0MF | COIL 1.0 UH POWER CHOKE 20% SMD |
| RYM06DTKH-S288 | CONN EDGECARD 12POS .156 EXTEND |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| EVAL-AD7731EB | 制造商:Analog Devices 功能描述:EVALUATION BOARD I.C. - Bulk |
| EVAL-AD7731EBZ | 功能描述:BOARD EVALUATION FOR AD7731 RoHS:是 類別:編程器，開發(fā)系統(tǒng) >> 評估板 - 模數(shù)轉(zhuǎn)換器 (ADC) 系列:- 產(chǎn)品培訓(xùn)模塊:Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:1 系列:- ADC 的數(shù)量:1 位數(shù):12 采樣率（每秒）:94.4k 數(shù)據(jù)接口:USB 輸入范圍:±VREF/2 在以下條件下的電源（標(biāo)準(zhǔn)）:- 工作溫度:-40°C ~ 85°C 已用 IC / 零件:MAX11645 已供物品:板，軟件 |
| EVAL-AD7732EB | 制造商:Analog Devices 功能描述:2-CHANNEL, ??10 V INPUT RANGE, HIGH THROUGHPUT, 24-BIT ADC |
| EVAL-AD7732EBZ | 功能描述:BOARD EVAL FOR AD7732 RoHS:是 類別:編程器，開發(fā)系統(tǒng) >> 評估板 - 模數(shù)轉(zhuǎn)換器 (ADC) 系列:- 產(chǎn)品培訓(xùn)模塊:Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:1 系列:- ADC 的數(shù)量:1 位數(shù):12 采樣率（每秒）:94.4k 數(shù)據(jù)接口:USB 輸入范圍:±VREF/2 在以下條件下的電源（標(biāo)準(zhǔn)）:- 工作溫度:-40°C ~ 85°C 已用 IC / 零件:MAX11645 已供物品:板，軟件 |
| EVAL-AD7734EBZ | 功能描述:BOARD EVALUATION FOR AD7734 RoHS:是 類別:編程器，開發(fā)系統(tǒng) >> 評估板 - 模數(shù)轉(zhuǎn)換器 (ADC) 系列:- 產(chǎn)品培訓(xùn)模塊:Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:1 系列:- ADC 的數(shù)量:1 位數(shù):12 采樣率（每秒）:94.4k 數(shù)據(jù)接口:USB 輸入范圍:±VREF/2 在以下條件下的電源（標(biāo)準(zhǔn)）:- 工作溫度:-40°C ~ 85°C 已用 IC / 零件:MAX11645 已供物品:板，軟件 |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。