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| 型号： | AD7991YRJZ-0RL |
| 厂商： | Analog Devices Inc |
| 文件页数： | 9/28页 |
| 文件大小： | 0K |
| 描述： | IC ADC 12BIT 4CH I2C SOT23-8 |
| 产品变化通告： | AD7991,5,9 Offset Error Change 17/Sept/2010 |
| 设计资源： | Using AD8599 as an Ultralow Distortion Driver for the AD7991 (CN0043) |
| 标准包装： | 10,000 |
| 位数： | 12 |
| 采样率（每秒）： | 1M |
| 数据接口： | I²C，串行 |
| 转换器数目： | 1 |
| 功率耗散（最大）： | 4.68mW |
| 电压电源： | 单电源 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | SOT-23-8 |
| 供应商设备封装： | SOT-23-8 |
| 包装： | 带卷 (TR) |
| 输入数目和类型： | 4 个单端，单极 |
| 配用： | EVAL-AD7991EBZ-ND - BOARD EVAL FOR AD7991 |
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AD7991/AD7995/AD7999
Rev. B | Page 17 of 28
THEORY OF OPERATION
The AD7991/AD7995/AD7999 are low power, 12-/10-/8-bit,
single-supply, 4-channel ADCs. Each part can be operated from
a single 2.35 V to 5.5 V supply.
The AD7991/AD7995/AD7999 provide the user with a 4-channel
multiplexer, an on-chip track-and-hold, an ADC, and an I2C-
compatible serial interface, all housed in an 8-lead SOT-23 package
that offers the user considerable space-saving advantages over
alternative solutions.
The AD7991/AD7995/AD7999 normally remains in a power-
down state while not converting. Therefore, when supplies are
first applied, the part is in a power-down state. Power-up is initiated
prior to a conversion, and the device returns to the power-down
state upon completion of the conversion. This automatic power-
down feature allows the device to save power between conversions.
This means any read or write operations across the I2C interface
can occur while the device is in power-down.
CONVERTER OPERATION
The AD7991/AD7995/AD7999 are successive approximation
show simplified schematics of the ADC during its acquisition
and conversion phases, respectively. Figure 18 shows the ADC
during its acquisition phase: SW2 is closed, SW1 is in Position A,
the comparator is held in a balanced condition, and the sampling
capacitor acquires the signal on VIN. The source driving the
analog input needs to settle the analog input signal to within
one LSB in 0.6 μs, which is equivalent to the duration of the
power-up and acquisition time.
06
46
1-
0
20
CAPACITIVE
DAC
VIN
COMPARATOR
CONTROL
LOGIC
SW1
A
B
SW2
AGND
Figure 18. ADC Acquisition Phase
When the ADC starts a conversion, as shown in Figure 19, SW2
opens and SW1 moves to Position B, causing the comparator to
become unbalanced. The input is disconnected when the con-
version begins. The control logic and the capacitive DAC are used
to add and subtract fixed amounts of charge from the sampling
capacitor to bring the comparator back into a balanced condition.
When the comparator is rebalanced, the conversion is complete.
The control logic generates the ADC output code. Figure 20 shows
the ADC transfer function.
06
46
1-
02
1
VIN
COMPARATOR
CONTROL
LOGIC
SW1
A
B
SW2
AGND
CAPACITIVE
DAC
Figure 19. ADC Conversion Phase
ADC Transfer Function
The output coding of the AD7991/AD7995/AD7999 is straight
binary. The designed code transitions occur at successive integer
LSB values (that is, 1 LSB, 2 LSB, and so on). The LSB size for
the AD7991/AD7995/AD7999 is VREF/4096, VREF/1024, and
characteristics for the AD7991/AD7995/AD7999.
111 ... 111
111 ... 110
111 ... 000
A
D
C
CO
DE
AGND + 1 LSB
ANALOG INPUT
0V TO REFIN
AD7991 1 LSB = REFIN/4096
AD7995 1 LSB = REFIN/1024
AD7999 1 LSB = REFIN/256
+REFIN – 1 LSB
011 ... 111
000 ... 010
000 ... 001
000 ... 000
06
46
1-
02
2
Figure 20. AD7991/AD7995/AD7999 Transfer Characteristics
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相关代理商/技术参数 |
参数描述 |
|---|---|
| AD7991YRJZ-1 | 制造商:AD 制造商全称:Analog Devices 功能描述:4-Channel, 12-/10-/8-Bit ADC with I2CCompatible Interface in 8-Lead SOT23 |
| AD7991YRJZ-1500RL7 | 功能描述:IC ADC 12BIT 4CH SAR I2C SOT23-8 RoHS:是 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:- 标准包装:1 系列:microPOWER™ 位数:8 采样率（每秒）:1M 数据接口:串行，SPI? 转换器数目:1 功率耗散（最大）:- 电压电源:模拟和数字 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:24-VFQFN 裸露焊盘 供应商设备封装:24-VQFN 裸露焊盘（4x4） 包装:Digi-Reel® 输入数目和类型:8 个单端，单极 产品目录页面:892 (CN2011-ZH PDF) 其它名称:296-25851-6 |
| AD7991YRJZ-1RL | 功能描述:IC ADC 12BIT 4CH I2C SOT23-8 RoHS:是 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:- 标准包装:2,500 系列:- 位数:16 采样率（每秒）:15 数据接口:MICROWIRE?，串行，SPI? 转换器数目:1 功率耗散（最大）:480µW 电压电源:单电源 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:38-WFQFN 裸露焊盘 供应商设备封装:38-QFN（5x7） 包装:带卷 (TR) 输入数目和类型:16 个单端，双极；8 个差分，双极 配用:DC1011A-C-ND - BOARD DELTA SIGMA ADC LTC2494 |
| AD7992 | 制造商:AD 制造商全称:Analog Devices 功能描述:2-Channel, 12-Bit ADC with I2C Compatible Interface in 10-Lead MSOP |
| AD7992_05 | 制造商:AD 制造商全称:Analog Devices 功能描述:2-Channel, 12-Bit ADC with I2C-Compatible |
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