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| 型號(hào)： | EVAL-AD7912CBZ |
| 廠商： | Analog Devices Inc |
| 文件頁數(shù)： | 8/32頁 |
| 文件大?。?/td> | 0K |
| 描述： | BOARD EVALUATION FOR AD7912 |
| 標(biāo)準(zhǔn)包裝： | 1 |
| ADC 的數(shù)量： | 1 |
| 位數(shù)： | 10 |
| 采樣率（每秒）： | 1M |
| 數(shù)據(jù)接口： | 串行 |
| 輸入范圍： | 0 ~ Vdd |
| 在以下條件下的電源（標(biāo)準(zhǔn)）： | 1MSPS 帶 3V 電壓時(shí)為 4.8mW |
| 工作溫度： | -40°C ~ 85°C |
| 已用 IC / 零件： | AD7912 |
| 已供物品： | 板，CD |
| 相關(guān)產(chǎn)品： | AD7912ARMZ-ND - IC ADC 10BIT DUAL 2CH 8MSOP AD7912AUJZ-REEL7TR-ND - IC ADC 10BIT DUAL 2CH TSOT-23-8 AD7912ARMZ-REEL7-ND - IC ADC 10BIT DUAL 2CH 8MSOP AD7912AUJZ-REEL-ND - IC ADC 10BIT DUAL 2CH TSOT-23-8 AD7912ARMZ-REEL-ND - IC ADC 10BIT DUAL 2CH 8MSOP |
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AD7912/AD7922
Rev. 0 | Page 16 of 32
TYPICAL CONNECTION DIAGRAM
Figure 22 shows a typical connection diagram for the AD7912/
AD7922. VREF is taken internally from VDD and as such VDD
should be well decoupled. This provides an analog input range
of 0 V to VDD. The conversion result is output in a 16-bit word
with two leading zeros, followed by the channel identifier bit
that identifies the channel converted, followed by the mode bit
that indicates the current mode of operation, and by the MSB of
the 12-bit or 10-bit result. For the AD7912, the 10-bit result is
followed by two trailing zeros. See the Serial Interface section.
Alternatively, because the supply current required by the
AD7912/AD7922 is so low, a precision reference can be used as
the supply source to the AD7912/AD7922. A REF19x voltage
reference (REF195 for 5 V or REF193 for 3 V) can be used to
supply the required voltage to the ADC (see Figure 22). This
configuration is especially useful, if the power supply is quite
noisy or if the system supply voltages are at some value other
than 5 V or 3 V (for example, 15 V). The REF19x outputs a
steady voltage to the AD7912/AD7922. If the low dropout
REF193 is used, the current it needs to supply to the AD7912/
AD7922 is typically1.5 mA. When the ADC is converting at a
rate of 1 MSPS, the REF193 needs to supply a maximum of
2 mA to the AD7912/AD7922. The load regulation of the
REF193 is typically 10 ppm/mA (REF193, VS = 5 V), which
results in an error of 20 ppm (60 V) for the 2 mA drawn from
it. This corresponds to a 0.082 LSB error for the AD7922 with
VDD = 3 V from the REF193 and a 0.061 LSB error for the
AD7912.
For applications where power consumption is a concern, the
power-down mode of the ADC and the sleep mode of the
REF19x reference should be used to improve power perform-
ance. See the Modes of Operation section.
04351-0-019
AD7912/
AD7922
VDD
VIN0
SERIAL
INTERFACE
0V TO VDD
INPUT
C/P
VIN1
GND
SCLK
CS
DIN
DOUT
0.1
F
10
F
1
F
TANT
0.1
F
680nF
3V
5V
SUPPLY
1.5mA
REF193
Figure 22. REF193 as Power Supply to AD7912/AD7922
Table 6 provides some typical performance data with various
references used as a VDD source and a 50 kHz input tone under
the same setup conditions.
Table 6. AD7922 Performance for Various Voltage
References IC
Reference Tied to VDD
AD7922 SNR Performance (dB)
AD780 at 3 V
73
REF193
72.42
ADR433
72.9
AD780 at 2.5 V
72.86
REF192
72.27
ADR421
72.75
ANALOG INPUT
Figure 23 shows an equivalent circuit of the analog input
structure of the AD7912/AD7922. The two diodes, D1 and D2,
provide ESD protection for the analog input. Care must be
taken to ensure that the analog input signal never exceeds the
supply rails by more than 300 mV, because this would cause
these diodes to become forward biased and start conducting
current into the substrate. The maximum current these diodes
can conduct without causing irreversible damage to the part is
10 mA.
04351-0-020
C1
6pF
C2
20pF
R1
D1
D2
VDD
VIN
Figure 23. Equivalent Analog Input Circuit
The capacitor C1 in Figure 23 is typically about 6 pF and can
primarily be attributed to pin capacitance. The resistor R1 is
a lumped component made up of the on resistance of the
track-and-hold switch and also includes the on resistance of
the input multiplexer. This resistor is typically about 100 .
The capacitor C2 is the ADC sampling capacitor and has a
capacitance of 20 pF typically.
For ac applications, removing high frequency components from
the analog input signal is recommended using a band-pass filter
on the relevant analog input pin. In applications where har-
monic distortion and signal-to-noise ratio are critical, the
analog input should be driven from a low impedance source.
Large source impedances can significantly affect the ac
performance of the ADC. This might necessitate the use of an
input buffer amplifier. The choice of the op amp is a function of
the particular application.
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相關(guān)代理商/技術(shù)參數(shù) |
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| EVAL-AD7920CB | 制造商:AD 制造商全稱:Analog Devices 功能描述:250 kSPS, 10-/12-Bit ADCs in 6-Lead SC70 |
| EVAL-AD7920CBZ | 功能描述:BOARD EVALUATION FOR AD7920 RoHS:是 類別:編程器，開發(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-AD7922CB | 制造商:Analog Devices 功能描述:EVALUATION BOARD I.C. - Bulk |
| EVAL-AD7922CBZ | 功能描述:BOARD EVAL FOR AD7922 RoHS:是 類別:編程器，開發(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-AD7923CB2 | 制造商:AD 制造商全稱:Analog Devices 功能描述:4-Channel, 200 kSPS, 12-Bit ADC with Sequencer in 16-Lead TSSOP |
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