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参数资料
| 型号： | MC34940EG |
| 厂商： | Freescale Semiconductor |
| 文件页数： | 10/12页 |
| 文件大小： | 0K |
| 描述： | IC IMAGING DEVICE ELECT 24-SOICW |
| 标准包装： | 30 |
| 类型： | 图像传感器 |
| 输入类型： | 逻辑 |
| 输出类型： | 电压 |
| 电流 - 电源： | 8mA |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 24-SOIC（0.295"，7.50mm 宽） |
| 供应商设备封装： | 24-SOIC W |
| 包装： | 管件 |
| 配用： | DEMO1985MC34940E-ND - KIT DEMO FOR MC34940E FAMILY |
Sensors
Freescale Semiconductor
7
MC34940
FEATURES
SHIELD DRIVER
A shield driver is included to minimize the electrode signal
along wires. This circuit provides a buffered version of the
returned AC signal from the electrode. Since it has nearly the
same amplitude and phase as the electrode signal, there is
little or no potential difference between the two signals
thereby canceling out any electric field. In effect, the shield
drive isolates the electrode signal from external virtual
grounds. A common application is to connect the Shield
Driver to the shield of a coax cable used to connect an
electrode to the corresponding electrode terminal. Another
typical use is to drive a ground plane that is used behind an
array of touch sensor electrodes in order to cancel out any
virtual grounds that could attenuate the AC signal.
TUNABLE FREQUENCY
The MC34940 offers 3 operating frequencies. In addition
to the default frequency of 120 kHz, the MC34940 has also
been characterized to work in two other frequencies (240 kHz
and 60 kHz) for applications with specific needs. These
frequencies are tunable by attaching a 20k and 82k resistor
at ROSC respectively. If a wider capacitance range is
needed, simply change the ROSC resistor value to 82k to
have the signal generator operate at 60 kHz which will extend
the capacitance range to 150 pF as seen on Figure 4. The
figure also shows that one can achieve higher sensitivity at
lower capacitances by setting the ROSC resistor value to
20k. All resistor values listed above are for 5% tolerance
resistors.
ADJUSTABLE RESPONSE TIME
The rectified sine wave is filtered by a Low Pass Filter
formed by an internal resistor and an external capacitor
attached to LP_CAP. The value of the external capacitor is
selected to allow the designer to optimize the balance
between noise and settling time. A typical value for the
external capacitor is 10 nF and in practice it will have a
response time of 2.5 ms. If faster response time is required a
1.0 nF capacitor can be used and it will have response times
around 500 s. Please note that reducing the LP_CAP
capacitor value increases noise accordingly.
Figure 4. Output Voltage vs. Capacitance at 3 Discrete Frequencies
Output Voltage vs Capacitance at 3 Discrete Frequencies
0
0.5
1
1.5
2
2.5
3
3.5
4
0
50
100
150
200
Capacitance (pF)
V
o
lt
ag
eO
u
tput
(V
ol
ts
)
120 kHz
240 kHz
60 kHz
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MC34940EG | 制造商:Freescale Semiconductor 功能描述:PROXIMITY SENSOR IC |
| MC34940EGR2 | 功能描述:近程传感器 ELECTRINIC FIELD IMAGING RoHS:否 制造商:Vishay Semiconductors 感应方式:Optical 感应距离:1 mm to 200 mm 电源电压:2.5 V to 3.6 V 安装风格:SMD/SMT 输出配置:Digital 最大工作温度:+ 85 C 最小工作温度:- 25 C 系列:VCNL3020 |
| MC34943 | 制造商:SPC Multicomp 功能描述:CONNECTOR MICRO SD HINGED |
| MC34945 | 制造商:SPC Multicomp 功能描述:CABLE ASSEMBLY HDMI TO HDMI 2M 制造商:SPC Multicomp 功能描述:CABLE ASSEMBLY, HDMI, TO HDMI, 2M 制造商:SPC Multicomp 功能描述:HDMI AUDIO/VIDEO CABLE, 2M, 28AWG, BLACK; Cable Length - Imperial:6.56ft; Cable Length - Metric:2m; Connector Type A:HDMI Plug; Connector Type B:HDMI Plug; Jacket Color:Black; Cable Assembly Type:HDMI; Cable Length:2m ;RoHS Compliant: Yes |
| MC34947 | 制造商:SPC Multicomp 功能描述:CABLE ASSEMBLY HDMI TO HDMI 3M 制造商:SPC Multicomp 功能描述:CABLE ASSEMBLY, HDMI, TO HDMI, 3M 制造商:SPC Multicomp 功能描述:HDMI AUDIO/VIDEO CABLE, 3M, 28AWG, BLACK; Cable Length - Imperial:9.84ft; Cable Length - Metric:3m; Connector Type A:HDMI Plug; Connector Type B:HDMI Plug; Jacket Color:Black; Cable Assembly Type:HDMI; Cable Length:3m ;RoHS Compliant: Yes |
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