參數(shù)資料
型號(hào)： EVAL-AD7661CBZ
廠(chǎng)商： Analog Devices Inc
文件頁(yè)數(shù)： 11/28頁(yè)
文件大?。?/td> 0K
描述： BOARD EVALUATION FOR AD7661
標(biāo)準(zhǔn)包裝： 1
系列： PulSAR®
ADC 的數(shù)量： 1
位數(shù)： 16
采樣率（每秒）： 100k
數(shù)據(jù)接口： 串行，并聯(lián)
輸入范圍： ±VREF
在以下條件下的電源（標(biāo)準(zhǔn)）： 16mW @ 100kSPS
工作溫度： -40°C ~ 85°C
已用 IC / 零件： AD7661
已供物品： 板，CD
相關(guān)產(chǎn)品： AD7661ACPZRL-ND - IC ADC 16BIT W/REF 48-LFCSP
AD7661ASTZ-ND - IC ADC 16BIT W/REF 48-LQFP
AD7661ACPZ-ND - IC ADC 16BIT W/REF 48LFCSP
AD7661ASTZRL-ND - IC ADC 16BIT W/REF 48LQFP
AD7661
Rev. 0 | Page 19 of 28
The noise generated by the driver amplifier needs to be
kept as low as possible in order to preserve the SNR and
transition noise performance of the AD7661. The noise
coming from the driver is filtered by the AD7661 analog
input circuit 1-pole low-pass filter made by R1 and C2 or
by the external filter, if one is used. The SNR degradation
due to the amplifier is
π
+
=
2
3
)
(
2
784
28
log
20
N
dB
LOSS
Ne
f
SNR
where:
f–3dB is the input bandwidth, in MHz, of the AD7661 (0.82)
or the cutoff frequency of the input filter, if one is
used.
N
is the noise factor of the amplifier (+1 in buffer
configuration).
eN
is the equivalent input noise voltage of the op amp, in
nV/√Hz.
For example, the OP184 driver, which has an equivalent
input noise of 4 nV/√Hz and a noise gain of +1 when
configured as a buffer, degrades the SNR by only 0.11 dB.
The driver needs to have a THD performance suitable to
that of the AD7661. Figure 15 gives the THD versus
frequency that the driver should exceed.
The OP184, OP162 or AD8519 meet these requirements and are
usually appropriate for almost all applications. As an alternative,
in very high speed and noise-sensitive applications, the AD8021
with an external 10 pF compensation capacitor can be used.
This capacitor should have good linearity as an NPO ceramic or
mica type. Moreover, the use of a noninverting +1 gain
arrangement is recommended and helps to obtain the best
signal-to-noise ratio.
The AD8022 could also be used if a dual version is needed
and gain of +1 is present. The AD829 is an alternative in
applications where high frequency (above 100 kHz)
performance is not required. In gain of +1 applications, it
requires an 82 pF compensation capacitor. The AD8610 is
an option when low bias current is needed in low
frequency applications.
Voltage Reference Input
The AD7661 allows the choice of either a very low temperature
drift internal voltage reference or an external 2.5 V reference.
Unlike many ADCs with internal references, the internal
reference of the AD7661 provides excellent performance and
can be used in almost all applications.
To use the internal reference along with the internal buffer,
PDREF and PDBUF should both be LOW. This will produce
1.2 V on REFBUFIN which, amplified by the buffer, will result
in a 2.5 V reference on the REF pin.
The output impedance of REFBUFIN is 11 k (minimum) when
the internal reference is enabled. It is necessary to
decouple
REFBUFIN with a ceramic capacitor greater than 10 nF. Thus
the capacitor provides an RC filter for noise reduction.
To use an external reference along with the internal buffer,
PDREF should be HIGH and PDBUF should be LOW. This
powers down the internal reference and allows the 2.5 V
reference to be applied to REFBUFIN.
To use an external reference directly on REF pin, PDREF and
PDBUF should both be HIGH.
PDREF and PDBUF power down the internal reference and the
internal reference buffer, respectively. Note that the PDREF and
PDBUF input current should never exceed 20 mA. This could
eventually occur when input voltage is above AVDD (for
instance at power up). In this case, a 100 series resistor is
recommended.
The internal reference is temperature compensated to 2.5 V ±
20 mV. The reference is trimmed to provide a typical drift of
3 ppm/°C . This typical drift characteristic is shown in Figure
22. For improved drift performance, an external reference, such
as the AD780, can be used.
The AD7661 voltage reference input REF has a dynamic input
impedance; it should therefore be driven by a low impedance
source with efficient decoupling between the REF and
REFGND inputs. This decoupling depends on the choice of the
voltage reference but usually consists of a low ESR tantalum
capacitor connected to REF and REFGND with minimum
parasitic inductance. A 10 F (X5R, 1206 size) ceramic chip
capacitor (or 47 F tantalum capacitor) is appropriate when
using either the internal reference or one of these
recommended reference voltages:
The low noise, low temperature drift ADR421 and AD780
The low power ADR291
The low cost AD1582
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參數(shù)描述
EVAL-AD7661EDZ 功能描述:BOARD EVAL FOR AD7661 RoHS:是 類(lèi)別:編程器，開(kāi)發(fā)系統(tǒng) >> 評(píng)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-AD7662CB 制造商:AD 制造商全稱(chēng):Analog Devices 功能描述:Evaluation Board AD766X/AD767X
EVAL-AD7663CB 制造商:Analog Devices 功能描述:
EVAL-AD7663CBZ 功能描述:BOARD EVALUATION FOR AD7663 RoHS:是 類(lèi)別:編程器，開(kāi)發(fā)系統(tǒng) >> 評(píng)估板 - 模數(shù)轉(zhuǎn)換器 (ADC) 系列:PulSAR® 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-AD7663EDZ 制造商:Analog Devices 功能描述:CONVERTER - ADC
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