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參數資料
| 型號： | MC33794DH |
| 廠商： | MOTOROLA INC |
| 元件分類： | 模擬信號調理 |
| 英文描述： | Electric Field Imaging Device |
| 中文描述： | SPECIALTY ANALOG CIRCUIT, PDSO44 |
| 封裝： | 16 X 11 MM, 1.30 MM HEIGHT, 0.65 MM PITCH, PLASTIC, HSOP-44 |
| 文件頁數： | 15/20頁 |
| 文件大小： | 491K |
| 代理商： | MC33794DH |
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.
相關PDF資料 |
PDF描述 |
|---|---|
| MC33794DWB | Electric Field Imaging Device |
| MC3392DW | LOW SIDE PROTECTED SWITCH |
| MC3392 | LOW SIDE PROTECTED SWITCH |
| MC3392T | LOW SIDE PROTECTED SWITCH |
| MC3392T-1 | LOW SIDE PROTECTED SWITCH |
相關代理商/技術參數 |
參數描述 |
|---|---|
| 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 類別:集成電路 (IC) >> 接口 - 傳感器和探測器接口 系列:- 其它有關文件:Automotive Product Guide 產品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:74 系列:- 類型:觸控式傳感器 輸入類型:數字 輸出類型:數字 接口:JTAG，串行 電流 - 電源:100µA 安裝類型:表面貼裝 封裝/外殼:20-TSSOP（0.173"，4.40mm 寬） 供應商設備封裝:20-TSSOP 包裝:管件 |
| MC33794DWBR2 | 功能描述:IC SENSOR ELECTRIC FIELD 54-SOIC RoHS:否 類別:集成電路 (IC) >> 接口 - 傳感器和探測器接口 系列:- 其它有關文件:Automotive Product Guide 產品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:74 系列:- 類型:觸控式傳感器 輸入類型:數字 輸出類型:數字 接口:JTAG，串行 電流 - 電源:100µA 安裝類型:表面貼裝 封裝/外殼:20-TSSOP（0.173"，4.40mm 寬） 供應商設備封裝:20-TSSOP 包裝:管件 |
| MC33794EK | 功能描述:近程傳感器 ODS 54LD RoHS:否 制造商:Vishay Semiconductors 感應方式:Optical 感應距離:1 mm to 200 mm 電源電壓:2.5 V to 3.6 V 安裝風格:SMD/SMT 輸出配置:Digital 最大工作溫度:+ 85 C 最小工作溫度:- 25 C 系列:VCNL3020 |
| MC33794EKR2 | 功能描述:近程傳感器 ODS 54LD RoHS:否 制造商:Vishay Semiconductors 感應方式:Optical 感應距離:1 mm to 200 mm 電源電壓:2.5 V to 3.6 V 安裝風格:SMD/SMT 輸出配置:Digital 最大工作溫度:+ 85 C 最小工作溫度:- 25 C 系列:VCNL3020 |
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