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參數(shù)資料
| 型號(hào)： | EVAL-AD7156EBZ |
| 廠商： | Analog Devices Inc |
| 文件頁數(shù)： | 17/28頁 |
| 文件大小： | 0K |
| 描述： | BOARD EVAL FOR AD7156 |
| 標(biāo)準(zhǔn)包裝： | 1 |
| 傳感器類型： | 觸摸，電容式 |
| 接口： | I²C |
| 電源電壓： | 1.8 V ~ 3.6 V |
| 嵌入式： | 否 |
| 已供物品： | 板，CD |
| 已用 IC / 零件： | AD7156 |
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AD7156
Rev. 0 | Page 24 of 28
HARDWARE DESIGN CONSIDERATIONS
OVERVIEW
The AD7156 is an interface to capacitive sensors.
On the input side, Sensor CX can be connected directly between
the AD7156 EXC and CIN pins. The way it is connected and the
electrical parameters of the sensor connection, such as parasitic
resistance or capacitance, can affect the system performance.
Therefore, any circuit with additional components in the capacitive
front end, such as overvoltage protection, has to be carefully
designed, considering the AD7156 specified limits and informa-
tion provided in this section.
On the output side, the AD7156 can work as a standalone device,
using the power-up default register settings and flagging the
result on the digital outputs. Alternatively, the AD7156 can be
interfaced to a microcontroller via the 2-wire serial interface,
offering flexibility by overwriting the AD7156 register values
from the host with a user-specific setup.
PARASITIC CAPACITANCE TO GROUND
DATA
CDC
EXC
CGND1
CIN
CGND2
CX
07
72
6-
0
52
Figure 42. Parasitic Capacitance to Ground
The CDC architecture used in the AD7156 measures the
capacitance, CX, connected between the EXC pins and the
CIN pins. In theory, any capacitance, CGND, to ground should
not affect the CDC result (see Figure 42).
The practical implementation of the circuitry in the chip implies
certain limits, and the result is gradually affected by capacitance
to ground (for information about the allowed capacitance to
GND for CIN and information about excitation see Table 1
and Figure 4 to Figure 9).
PARASITIC RESISTANCE TO GROUND
DATA
CDC
EXC
RGND1
CIN
RGND2
CX
07
72
6-
0
53
Figure 43. Parasitic Resistance to Ground
The AD7156 CDC result is affected by a leakage current from
CX to ground; therefore, CX should be isolated from the ground.
The equivalent resistance between CX and ground should be
to Figure 13.
PARASITIC PARALLEL RESISTANCE
DATA
CDC
EXC
CIN
RP
CX
07
72
6-
05
4
Figure 44. Parasitic Parallel Resistance
The AD7156 CDC measures the charge transfer between the
EXC and CIN pins. Any resistance connected in parallel to the
resistance of the sensor, also transfers charge. Therefore, the
parallel resistor is seen as an additional capacitance in the
output data. The equivalent parallel capacitance (or error
caused by the parallel resistance) can be approximately
calculated as
4
1
×
=
EXC
P
f
R
C
where:
RP is the parallel resistance.
fEXC is the excitation frequency.
For additional information, see Figure 15.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| EVAL-AD7156EBZ | 制造商:Analog Devices 功能描述:EVAL BOARD, AD7156 2CH CAPACITANCE CONVE |
| EVAL-AD7170EBZ | 功能描述:BOARD EVAL FOR AD7170 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-AD7171EBZ | 功能描述:BOARD EVAL FOR AD7171 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-AD7173-8SDZ | 制造商:Analog Devices 功能描述:EVAL BOARD MULTI CHANNEL - Boxed Product (Development Kits) |
| EVAL-AD7175-8SDZ | 功能描述:AD7175-8 - 24 Bit 250k Samples per Second Analog to Digital Converter (ADC) Evaluation Board 制造商:analog devices inc. 系列:- 零件狀態(tài):有效 A/D 轉(zhuǎn)換器數(shù):1 位數(shù):24 采樣率（每秒）:250k 數(shù)據(jù)接口:并聯(lián) 輸入范圍:±VREF 不同條件下的功率（典型值）:105mW @ 250kSPS 使用的 IC/零件:AD7175-8 所含物品:板，電源 標(biāo)準(zhǔn)包裝:1 |
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