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| 型号： | AD7985BCPZ-RL7 |
| 厂商： | Analog Devices Inc |
| 文件页数： | 5/28页 |
| 文件大小： | 0K |
| 描述： | IC ADC 16B 2.5MSPS PULSR 20LFCSP |
| 标准包装： | 1,500 |
| 系列： | PulSAR® |
| 位数： | 16 |
| 采样率（每秒）： | 2.5M |
| 数据接口： | DSP，MICROWIRE?，QSPI?，串行，SPI? |
| 转换器数目： | 1 |
| 功率耗散（最大）： | 33mW |
| 电压电源： | 模拟和数字 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 20-VFQFN 裸露焊盘，CSP |
| 供应商设备封装： | 20-LFCSP-VQ |
| 包装： | 带卷 (TR) |
| 输入数目和类型： | 1 个伪差分，单极 |
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AD7985
Rev. A | Page 13 of 28
THEORY OF OPERATION
COMP
SWITCHES CONTROL
BUSY
OUTPUT CODE
CNV
CONTROL
LOGIC
SW+
LSB
SW–
LSB
IN+
REF
REFGND
IN–
MSB
C
4C
2C
16,384C
32,768C
C
4C
2C
16,384C
32,768C
07947-
005
Figure 21. ADC Simplified Schematic
CIRCUIT INFORMATION
The AD7985 is a fast, low power, single-supply, precise, 16-bit
ADC using a successive approximation architecture. The AD7985
features different modes to optimize performance according to the
application. In turbo mode, the AD7985 is capable of converting
2,500,000 samples per second (2.5 MSPS).
The AD7985 provides the user with an on-chip track-and-hold
and does not exhibit any pipeline delay or latency, making it
ideal for multiple multiplexed channel applications.
The AD7985 can be interfaced to any 1.8 V to 2.7 V digital logic
family. It is available in a space-saving 20-lead LFCSP that allows
flexible configurations. It is pin-for-pin compatible with the
18-bit AD7986.
CONVERTER OPERATION
The AD7985 is a successive approximation ADC based on a
charge redistribution DAC. Figure 21 shows the simplified
schematic of the ADC. The capacitive DAC consists of two
identical arrays of 16 binary-weighted capacitors that are
connected to the two comparator inputs.
During the acquisition phase, the terminals of the array tied to
the input of the comparator are connected to AGND via SW+
and SW. All independent switches are connected to the analog
inputs. Therefore, the capacitor arrays are used as sampling
capacitors and acquire the analog signal on the IN+ and IN
inputs. When the acquisition phase is completed and the CNV
input goes high, a conversion phase is initiated.
When the conversion phase begins, SW+ and SW are opened
first. The two capacitor arrays are then disconnected from the
analog inputs and connected to the REFGND input. Therefore,
the differential voltage between the IN+ and IN inputs captured
at the end of the acquisition phase is applied to the comparator
inputs, causing the comparator to become unbalanced. By switch-
ing each element of the capacitor array between REFGND and
REF, the comparator input varies by binary-weighted voltage
steps (VREF/2, VREF/4, … VREF/65,536). The control logic toggles
these switches, starting with the MSB, to bring the comparator
back into a balanced condition. After the completion of this
process, the part returns to the acquisition phase, and the control
logic generates the ADC output code and a busy signal indicator.
Because the AD7985 has an on-board conversion clock, the
serial clock, SCK, is not required for the conversion process.
CONVERSION MODES OF OPERATION
The AD7985 features two conversion modes of operation: turbo
and normal. Turbo conversion mode (TURBO is high) allows
the fastest conversion rate of up to 2.5 MSPS and does not
power down between conversions. The first conversion in turbo
mode should be ignored because it contains meaningless data.
For applications that require lower power and slightly slower
sampling rates, the normal mode (TURBO is low) allows a
maximum conversion rate of 2.0 MSPS and powers down
between conversions. The first conversion in normal mode
contains meaningful data.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| AD7986 | 制造商:AD 制造商全称:Analog Devices 功能描述:1 nV/√Hz, Low Power |
| AD7986BCPZ | 功能描述:IC ADC 18BIT 2MSPS SAR 20LFCSP RoHS:是 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:- 其它有关文件:TSA1204 View All Specifications 标准包装:1 系列:- 位数:12 采样率（每秒）:20M 数据接口:并联 转换器数目:2 功率耗散（最大）:155mW 电压电源:模拟和数字 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-TQFP 供应商设备封装:48-TQFP（7x7） 包装:Digi-Reel® 输入数目和类型:4 个单端，单极；2 个差分，单极 产品目录页面:1156 (CN2011-ZH PDF) 其它名称:497-5435-6 |
| AD7986BCPZ-RL7 | 功能描述:IC ADC 18BIT 2MSPS SAR 20LFCSP 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:- 位数:14 采样率（每秒）:83k 数据接口:串行，并联 转换器数目:1 功率耗散（最大）:95mW 电压电源:双 ± 工作温度:0°C ~ 70°C 安装类型:通孔 封装/外壳:28-DIP（0.600"，15.24mm） 供应商设备封装:28-PDIP 包装:管件 输入数目和类型:1 个单端，双极 |
| AD7986BCPZ-U1 | 制造商:Analog Devices 功能描述:16-BIT, 10MSPS PULSAR DIFFERENTIAL ADC - Rail/Tube |
| AD7986XCPZ-U1 | 制造商:Analog Devices 功能描述:16-BIT, 10MSPS PULSAR DIFFERENTIAL ADC - Rail/Tube |
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