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参数资料
| 型号： | EVAL-AD7994EBZ |
| 厂商： | Analog Devices Inc |
| 文件页数： | 7/32页 |
| 文件大小： | 0K |
| 描述： | BOARD EVAL FOR AD7994 |
| 标准包装： | 1 |
| ADC 的数量： | 1 |
| 位数： | 12 |
| 采样率（每秒）： | 188k |
| 数据接口： | 串行 |
| 输入范围： | 0 ~ 5.5 V |
| 在以下条件下的电源（标准）： | 7.7mW @ 188kSPS，5.5 V |
| 工作温度： | -40°C ~ 125°C |
| 已用 IC / 零件： | AD7994 |
| 已供物品： | 板，缆线，CD |
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AD7993/AD7994
Rev. 0 | Page 15 of 32
CIRCUIT INFORMATION
The AD7993/AD7994 are low power, 10- and 12-bit, single-
supply, 4-channel A/D converters, respectively. The parts can
be operated from a 2.7 V to 5.5 V supply.
The AD7993/AD7994 provide the user with a 4-channel
multiplexer, an on-chip track-and-hold, an A/D converter, an
on-chip oscillator, internal data registers, and an I2C-compatible
serial interface, all housed in a 16-lead TSSOP package that
offers the user considerable space-saving advantages over
alternative solutions. The AD7993/AD7994 require an external
reference in the range of 1.2 V to VDD.
The AD7993/AD7994 normally remain in a power-down state
while not converting. When supplies are first applied, the parts
come up in a power-down state. Power-up is initiated prior to
a conversion, and the device returns to shutdown upon com-
pletion of the conversion. Conversions can be initiated on the
AD7993/AD7994 by pulsing the CONVST signal, using an
automatic cycle interval mode, or using a command mode
where wake-up and a conversion occurs during a write address
function (see the Modes of Operation section). When the con-
version is complete, the AD7993/AD7994 again enter shutdown
mode. This automatic shut-down feature allows power saving
between conversions. Any read or write operations across the
I2C interface can occur while the devices are in shutdown.
CONVERTER OPERATION
The AD7993/AD7994 are successive approximation analog-to-
digital converters based around a capacitive DAC. Figure 18 and
Figure 19 show simplified schematics of an ADC during the
acquisition and conversion phase, respectively. Figure 18 shows
an ADC during the acquisition phase. SW2 is closed and SW1
is in Position A. The comparator is held in a balanced condition
and the sampling capacitor acquires the signal on VINx.
CAPACITIVE
DAC
VIN
COMPARATOR
CONTROL
LOGIC
SW1
A
B
SW2
AGND
03472-0-018
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 once 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.
VIN
COMPARATOR
CONTROL
LOGIC
SW1
A
B
SW2
AGND
CAPACITIVE
DAC
03472-0-019
Figure 19. ADC Conversion Phase
ADC Transfer Function
The output coding of the AD7993/AD7994 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 is
REFIN/1024 for the AD7993 and REFIN/4096 for the AD7994.
Figure 20 shows the ideal transfer characteristic for the
AD7993/AD7994.
000...000
ADC
CODE
ANALOG INPUT
0V TO REFIN
111...111
000...001
000...010
111...110
111...000
011...111
AGND + 1LSB
+REFIN – 1LSB
AD7994 1LSB = REFIN/4096
AD7993 1LSB = REFIN/1024
03472-0-020
Figure 20. AD7993/AD7994 Transfer Characteristic
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相关代理商/技术参数 |
参数描述 |
|---|---|
| EVAL-AD7995EBZ | 功能描述:BOARD EVAL FOR AD7995 RoHS:是 类别:编程器，开发系统 >> 评估板 - 模数转换器 (ADC) 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:1 系列:- ADC 的数量:1 位数:12 采样率（每秒）:94.4k 数据接口:USB 输入范围:±VREF/2 在以下条件下的电源（标准）:- 工作温度:-40°C ~ 85°C 已用 IC / 零件:MAX11645 已供物品:板，软件 |
| EVAL-AD7997CBZ | 制造商:Analog Devices 功能描述:EVALUATION CONTROL BOARD (ROHS) - Bulk |
| EVAL-AD7997EBZ | 功能描述:BOARD EVAL FOR AD7997 RoHS:是 类别:编程器，开发系统 >> 评估板 - 模数转换器 (ADC) 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:1 系列:- ADC 的数量:1 位数:12 采样率（每秒）:94.4k 数据接口:USB 输入范围:±VREF/2 在以下条件下的电源（标准）:- 工作温度:-40°C ~ 85°C 已用 IC / 零件:MAX11645 已供物品:板，软件 |
| EVAL-AD7998CB | 制造商:Analog Devices 功能描述:EVALUATION CONTROL BOARD. - Bulk |
| EVAL-AD7998CBZ | 制造商:Analog Devices 功能描述:EVALUATION CONTROL BOARD. - Bulk |
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