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参数资料
| 型号： | MC33794 |
| 厂商： | 飞思卡尔半导体(中国)有限公司 |
| 英文描述： | Electric Field Imaging Device(电场成像设备) |
| 中文描述： | 电场成像设备（电场成像设备） |
| 文件页数： | 15/20页 |
| 文件大小： | 742K |
| 代理商： | MC33794 |
MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA
33794
15
SYSTEM/APPLICATION INFORMATION
INTRODUCTION
The 33794 is intended for use in detecting objects using an
electric field. The IC generates a low radio frequency sine
wave. The frequency is set by an external resistor and is
optimized for 120 kHz. The sine wave has very low harmonic
content to reduce potential interference at higher harmonically
related frequencies. The internal generator produces a
nominal 5.0 V peak-to-peak output that is passed through an
internal resistor of about 22 k
. An internal multiplexer routes
the signal to one of 11 pins under control of the ABCD input
pins. A receiver multiplexer simultaneously connected to the
selected electrode routes its signal to a detector, which
converts the sine wave to a DC level. This DC level is filtered
by an external capacitor and is multiplied and offset to increase
sensitivity. All of the unselected electrode outputs are
grounded by the device. The current flowing between the
selected electrode and the other grounded electrodes plus
other grounded objects around the electrode causes a voltage
drop across the internal resistance. Objects brought into or out
of the electric field change the current and resulting voltage at
the IC pin, which in turn reduces the voltage at LP_CAP and
LEVEL.
A shield driver is included to minimize the effect of
capacitance caused by using coaxial cables to connect to
remote electrodes. By driving the coax shield with this signal,
the shield voltage follows that of the center conductor,
significantly reducing the effective capacitance of the coax and
maintaining sensitivity to the capacitance at the electrode.
The 33794 is made to work with and support a
microcontroller. It provides two voltage regulators, a Power-
ON-reset/out-of-range voltage detector, watchdog circuit,
lamp driver and sense circuit, and a physical layer ISO-9141
communications interface.
BLOCK DIAGRAM COMPONENTS
Refer to
Figure 1
, 33794 Internal Block Diagram, page 2, for
a graphic representation of the block diagram information in
this section.
OSC
This section generates a high purity sine wave. The center
frequency is controlled by a resistor attached to R_OSC. The
normal operating frequency is around 120 kHz. A square wave
version of the frequency output is available at CLK. Timing for
the Power-ON Reset and watchdog (POR/WD) circuit are
derived from this oscillator’s frequency.
MUX OUT
This circuit directs the output of the sine wave to one of nine
possible electrode outputs or two reference pins. All unused
pins are automatically grounded. The selected output is
controlled by the ABCD inputs.
MUX IN
This circuit connects the selected electrode, reference, or
one of two internal nodes to an amplifier/detector. The
selection is controlled by the ABCD inputs and follows the
driven electrode/reference when one is selected.
RECT
The rectifier circuit detects the level from MUX IN by
offsetting the midpoint of the sine wave to zero volts and
inverting the waveform when it is below the midpoint. It is
important to avoid DC loading of the signal, which would cause
a shift in the midpoint voltage of the signal from the MUX IN.
LPF
The rectified sine wave is filtered by a low pass function in
the LPF formed by an internal resistance and an external
capacitance attached to LP_CAP. The nominal value of the
internal resistance is 50 k
. The value of the external capacitor
is selected to provide filtering of noise while still allowing the
desired settling time for the detector output. A 10 nF capacitor
would allow 99% settling in less than 5.0 ms.
GAIN and OFFSET
This circuit multiplies the detected and filtered signal by a
gain and offsets the result by a DC level. This results in an
output range that covers 1.0 V to 4.0 V for capacitive loading
of the field in the range of 10 pF to 100 pF. This allows higher
sensitivity for a digital-to-analog converter with a 0 V-to-5.0 V
input range.
ATTN
This circuit passes the undetected signal to SIGNAL for
external use.
LAMP CKT
This section controls the operation of the LAMP_OUT pin.
When LAMP_CTRL is asserted, LAMP_OUT is pulled to
LAMP_GND. If one side of an indicator lamp or LED (with
appropriate current setting resistor) is connected to a positive
voltage source and the other is connected to LAMP_OUT, and
LAMP_GND is connected to ground, the lamp will light. This
circuit provides current limiting to prevent damage to itself in
the case of a shorted lamp or during a high-surge condition
typical of an incandescent lamp burnout.
F
Freescale Semiconductor, Inc.
Go to: www.freescale.com
n
.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MC33794DH | 功能描述:IC SENSOR ELECTRIC FIELD 44-HSOP RoHS:是 类别:集成电路 (IC) >> 接口 - 传感器和探测器接口 系列:- 其它有关文件:Automotive Product Guide 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:74 系列:- 类型:触控式传感器 输入类型:数字 输出类型:数字 接口:JTAG，串行 电流 - 电源:100µA 安装类型:表面贴装 封装/外壳:20-TSSOP（0.173"，4.40mm 宽） 供应商设备封装:20-TSSOP 包装:管件 |
| MC33794DHR2 | 制造商:Rochester Electronics LLC 功能描述:OCCUPANT DETECT E-FIELD SENSOR FOR MCU SUPPORT - Bulk |
| MC33794DWB | 功能描述:IC SENSOR ELECTRIC FIELD 54-SOIC RoHS:否 类别:集成电路 (IC) >> 接口 - 传感器和探测器接口 系列:- 其它有关文件:Automotive Product Guide 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:74 系列:- 类型:触控式传感器 输入类型:数字 输出类型:数字 接口:JTAG，串行 电流 - 电源:100µA 安装类型:表面贴装 封装/外壳:20-TSSOP（0.173"，4.40mm 宽） 供应商设备封装:20-TSSOP 包装:管件 |
| MC33794DWBR2 | 功能描述:IC SENSOR ELECTRIC FIELD 54-SOIC RoHS:否 类别:集成电路 (IC) >> 接口 - 传感器和探测器接口 系列:- 其它有关文件:Automotive Product Guide 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:74 系列:- 类型:触控式传感器 输入类型:数字 输出类型:数字 接口:JTAG，串行 电流 - 电源:100µA 安装类型:表面贴装 封装/外壳:20-TSSOP（0.173"，4.40mm 宽） 供应商设备封装:20-TSSOP 包装:管件 |
| MC33794EK | 功能描述:近程传感器 ODS 54LD 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 |
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