參數(shù)資料
型號(hào)： AD7656
廠商： Analog Devices, Inc.
英文描述： 250 kSPS, 6-Channel,Simultaneous Sampling, Bipolar 12/14/16-Bit ADC
中文描述： 250 kSPS的6通道同步采樣ADC的雙極12/14/16-Bit
文件頁(yè)數(shù)： 15/25頁(yè)
文件大?。?/td> 308K
代理商： AD7656
Preliminary Technical Data
AD7658/AD7657/AD7656
CONVERTER DETAILS
The AD7658/AD7657/AD7656 are high-speed, low power
converters that allow the simultaneous sampling of their six on-
chip ADCs. The Analog Inputs on the
AD7658/AD7657/AD7656 can accept True bipolar Input
signals, the RANGE pin/RNG bits are used to select between ±4
x VREF or ±2 x VREF as the Input Range for the next
conversion.
Rev. PrI | Page 15 of 25
The AD7658/AD7657/AD7656 contain six SAR ADCs, six
track-and-hold amplifiers, on-chip 2.5V reference, reference
buffers, high speed parallel and serial interfaces. The
AD7658/AD7657/AD7656 allow the simultaneous sampling of
all six ADCs when all three CONVST signals are tied together.
Alternatively the six ADCs can be grouped into three pairs.
Each pair has an associated CONVST signal used to initiate
simultaneous sampling on each ADC pair, on four ADCs or all
six ADCs. CONVSTA is used to initiate simultaneous sampling
on V1 and V2, CONVSTB is used to initiate simultaneous
sampling on V3 and V4, and CONVSTC is used to initiate
simultaneous sampling on V5 and V6.
A conversion is initiated on the AD7658/AD7657/AD7656 by
pulsing the CONVSTX input. On the rising edge of CONVSTX
the track-and-hold on the selected ADCs will be placed into
hold mode and the conversions are started. After the rising edge
of CONVSTX the BUSY signal will go high to indicate the
conversion is taking place. The conversion clock for the part is
internally generated and the conversion time for the
AD7658/AD7657/AD7656 is 3 μs from the rising edge of
CONVSTX. The BUSY signal will return low to indicate the end
of conversion. On the falling edge of BUSY the track-and-hold
will return to track mode. Data can be read from the output
register via the parallel or serial interface.
Track-and-Hold Section
The track-and-Hold amplifiers on the
AD7658/AD7657/AD7656 allow the ADCs to accurately
convert an input sine wave of full-scale amplitude to 12/14/16-
bit resolution. The input bandwidth of the track-and-hold
amplifiers is greater that the Nyquist rate of the ADC even
when the AD7658/AD7657/AD7656 is operating at its
maximum throughput rate. The AD7658/AD7657/AD7656 can
handle input frequencies up to 8 MHz.
The track-and-hold amplifiers sample their respective inputs
simultaneously on the rising edge of CONVSTX. The aperture
time for the track-and-hold, (i.e. the delay time between the
external CONVSTX signal actually going into hold), is typically
20ns. This is well matched across all six track-and-holds on the
one device and also from device to device. This allows more
than six ADCs to be simultaneously sampled. The end of the
conversion is signaled by the falling edge of BUSY and its at this
point the track-and-holds return to track mode and the
acquisition time begins.
Analog Input Section
The AD7658/AD7657/AD7656 can handle True bipolar input
voltages. The logic level on the RANGE pin or the value written
to the RNGX bits in the Control register will determine the
Analog input Range on the AD7658/AD7657/AD7656 for the
next conversion. When the RANGE pin/ RNGX bit is 1 the
Analog input range for the next conversion is ±2 x VREF, when
the RANGE pin/ RNG bit is 0 the Analog Input range for the
next conversion is ±4 x VREF.
D
D
VDD
C2
R1
V1
VSS
C1
Figure 3. Equivalent Analog Input Structure
Figure 3 shows an equivalent circuit of the analog input
structure of the AD7658/AD7657/AD7656. The two diodes, D1
and D2, provide ESD protection for the analog inputs. Care
must be taken to ensure that the analog input signal never
exceeds the V
DD
and V
SS
supply rails by more than TBD mV.
This will cause these diodes to become forward-biased and to
start conducting current into the substrate. The maximum
current these diodes can conduct without causing irreversible
damage to the part is 10 mA. Capacitor C1 in Figure 3 is
typically about 5 pF and can be attributed primarily to pin
capacitance. Resistor R1 is a lumped component made up of the
on resistance of a switch (track-and-hold switch). This resistor
is typically about 25 . Capacitor C2 is the ADC sampling
capacitor and has a capacitance of 25 pF typically.
相關(guān)PDF資料
PDF描述
AD7656BSTZ 250 kSPS, 6-Channel,Simultaneous Sampling, Bipolar 12/14/16-Bit ADC
AD7656BSTZ-REEL 250 kSPS, 6-Channel,Simultaneous Sampling, Bipolar 12/14/16-Bit ADC
AD7657 250 kSPS, 6-Channel,Simultaneous Sampling, Bipolar 12/14/16-Bit ADC
AD7657BSTZ 250 kSPS, 6-Channel,Simultaneous Sampling, Bipolar 12/14/16-Bit ADC
AD7657BSTZ-REEL 250 kSPS, 6-Channel,Simultaneous Sampling, Bipolar 12/14/16-Bit ADC
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
AD7656-1 制造商:AD 制造商全稱:Analog Devices 功能描述:250 kSPS, 6-Channel, Simultaneous Sampling, Bipolar, 16-/14-/12-Bit ADC
AD7656A-1BSTZ 功能描述:16 Bit Analog to Digital Converter 6 Input 6 SAR 64-LQFP (10x10) 制造商:analog devices inc. 系列:iCMOS? 包裝:托盤(pán) 零件狀態(tài):有效 位數(shù):16 采樣率（每秒）:250k 輸入數(shù):6 輸入類型:單端 數(shù)據(jù)接口:SPI，并聯(lián)，DSP 配置:S/H-ADC 無(wú)線電 - S/H:ADC:1:1 A/D 轉(zhuǎn)換器數(shù):6 架構(gòu):SAR 參考類型:外部， 內(nèi)部 電壓 - 電源，模擬:5V 電壓 - 電源，數(shù)字:5V 特性:仿真采樣，真正的雙極性 工作溫度:-40°C ~ 85°C 封裝/外殼:64-LQFP 供應(yīng)商器件封裝:64-LQFP（10x10） 標(biāo)準(zhǔn)包裝:1
AD7656A-1BSTZ-RL 功能描述:16 Bit Analog to Digital Converter 6 Input 6 SAR 64-LQFP (10x10) 制造商:analog devices inc. 系列:iCMOS? 包裝:帶卷（TR） 零件狀態(tài):有效 位數(shù):16 采樣率（每秒）:250k 輸入數(shù):6 輸入類型:單端 數(shù)據(jù)接口:SPI，并聯(lián)，DSP 配置:S/H-ADC 無(wú)線電 - S/H:ADC:1:1 A/D 轉(zhuǎn)換器數(shù):6 架構(gòu):SAR 參考類型:外部， 內(nèi)部 電壓 - 電源，模擬:5V 電壓 - 電源，數(shù)字:5V 特性:仿真采樣，真正的雙極性 工作溫度:-40°C ~ 85°C 封裝/外殼:64-LQFP 供應(yīng)商器件封裝:64-LQFP（10x10） 標(biāo)準(zhǔn)包裝:1,500
AD7656ABSTZ 功能描述:16 Bit Analog to Digital Converter 6 Input 6 SAR 64-LQFP (10x10) 制造商:analog devices inc. 系列:iCMOS? 包裝:托盤(pán) 零件狀態(tài):有效 位數(shù):16 采樣率（每秒）:250k 輸入數(shù):6 輸入類型:單端 數(shù)據(jù)接口:SPI，并聯(lián)，DSP 配置:S/H-ADC 無(wú)線電 - S/H:ADC:1:1 A/D 轉(zhuǎn)換器數(shù):6 架構(gòu):SAR 參考類型:外部， 內(nèi)部 電壓 - 電源，模擬:5V 電壓 - 電源，數(shù)字:5V 特性:仿真采樣，真正的雙極性 工作溫度:-40°C ~ 85°C 封裝/外殼:64-LQFP 供應(yīng)商器件封裝:64-LQFP（10x10） 標(biāo)準(zhǔn)包裝:1
AD7656ABSTZ-RL 功能描述:16 Bit Analog to Digital Converter 6 Input 6 SAR 64-LQFP (10x10) 制造商:analog devices inc. 系列:iCMOS? 包裝:帶卷（TR） 零件狀態(tài):有效 位數(shù):16 采樣率（每秒）:250k 輸入數(shù):6 輸入類型:單端 數(shù)據(jù)接口:SPI，并聯(lián)，DSP 配置:S/H-ADC 無(wú)線電 - S/H:ADC:1:1 A/D 轉(zhuǎn)換器數(shù):6 架構(gòu):SAR 參考類型:外部， 內(nèi)部 電壓 - 電源，模擬:5V 電壓 - 電源，數(shù)字:5V 特性:仿真采樣，真正的雙極性 工作溫度:-40°C ~ 85°C 封裝/外殼:64-LQFP 供應(yīng)商器件封裝:64-LQFP（10x10） 標(biāo)準(zhǔn)包裝:1,500
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