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參數(shù)資料
| 型號： | PC33975A |
| 廠商： | 飛思卡爾半導(dǎo)體(中國)有限公司 |
| 英文描述： | Multiple Switch Detection Interface with Suppressed Wake-Up and 32mA Wetting Current |
| 中文描述： | 多交換檢測接口，具有抑制喚醒和32毫安濕電流 |
| 文件頁數(shù)： | 23/32頁 |
| 文件大?。?/td> | 641K |
| 代理商： | PC33975A |
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Analog Integrated Circuit Device Data
Freescale Semiconductor
23
33975
TYPICAL APPLICATIONS
OPERATIONAL MODES
Figure 13. Analog Ratiometric Conversion
To read a potentiometer sensor, the wiper should be
grounded and brought back to the module ground, as
illustrated in
Figure 13
. With the wiper changing the
impedance of the sensor, the analog voltage on the input will
represent the position of the sensor.
Using the Analog feature to provide 4.0 mA of pull-up
current to an analog sensor may induce error due to the
accuracy of the current source. For this reason, a ratiometric
conversion must be considered. Using two current sources
(one for the sensor and one to set the reference voltage to the
A/D converter) will yield a maximum error (owing to the
33975) of 4%.
Higher accuracy may be achieved through module level
calibration. In this example, we use the resistor values from
Figure 13
and assume the current sources are 4% from each
other. The user may use the module end-of-line tester to
calculate the error in the A/D conversion. By placing a
1.0 k
, 0.1% resistor in the end-of-line test equipment and
assuming a perfect 4.0 mA current source from the 33975, a
calculated A/D conversion may be obtained.
Using the equation yields the
following:
The ADC value of 213 counts is the value with 0% error
(neglecting the resistor tolerance and AMUX input offset
voltage). Now we can calculate the count value induced by
the mismatch in current sources. From a sample device the
maximum current source was measured at 3.979 mA and
minimum current source was measured at 3.933 mA. This
yields 1.16% error in A/D conversion due to the current
source mismatch. The A/D measurement will be as follows:
This A/D conversion is 1.16% low in value. The error
correction factor of 1.0115 may be used to correct the value:
An error correction factor may then be stored in E
2
memory and used in the A/D calculation for the specific input.
Each input used as analog measurement will have a
dedicated calibrated error correction factor.
POWER MOSFET/LED DRIVER AND MONITOR
Because of the flexible programming of the 33975 device,
it may be used to drive small loads like LEDs or MOSFET
gates. It was specifically designed to power up in the Normal
mode with the inputs tri-state. This was done to ensure the
LEDs or MOSFETs connected to the 33975 power up in the
off-state. The Switch Programmable (SP0–SP7) inputs have
a source-and-sink capability, providing effective MOSFET
gate control. To complete the circuit, a pull-down resistor
should be used to keep the gate from floating during the
Sleep modes.
Figure 14
, page
24
, shows an application
where the SG0 input is used to monitor the drain-to-source
voltage of the external MOSFET. The 750
resistor is used
to set the drain-to-source trip voltage. With the 4.0 mA
current source enabled, an interrupt will be generated when
the drain-to-source voltage is approximately 1.0 V.
VDD
VPWR
V
DD
SI
SO
INT
SCLK
CS
AMUX
MOSI
SCLK
CS
MISO
INT
AN0
VBAT
SP0
SP1
SP7
SG1
SG0
SG12
SG13
WAKE
VBAT
32
mA
4.0
mA
V
PWR
4.0 mA
4.0 mA
1.21 k
0.1%
4.36 V to 5.32 V
Analog
Ports
V
REF(H)
V
REF(L)
Analog Sensor
or Analog Switch
R
2
I
2
I
1
R
1
V
PWR
4.0
mA
V
PWR
V
PWR
mA
32
33975
MCU
ADC = I1 x R1
I2 x R2x 225
ADC = 4.0 mA x 1.0 k
4.0 mA x 1.21 k
x 225
ADC = 210 counts
ADC = 3.933 mA x 1.0 k
3.979 mA x 1.21 k
x 225
ADC = 208 counts
ADC = 208 counts x 1.0116
ADC = 210 counts
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| PC33975AEK | Multiple Switch Detection Interface with Suppressed Wake-Up and 32mA Wetting Current |
| PC33975AR2 | Multiple Switch Detection Interface with Suppressed Wake-Up and 32mA Wetting Current |
| PC3S12XEP100J1CAA | Microcontrollers |
| PC3S12XEP100J1CAAR | Microcontrollers |
| PC3S12XEP100J1CAG | Microcontrollers |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| PC33975AEK | 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:Multiple Switch Detection Interface with Suppressed Wake-Up and 32mA Wetting Current |
| PC33975AR2 | 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:Multiple Switch Detection Interface with Suppressed Wake-Up and 32mA Wetting Current |
| PC33981PNA/R2 | 制造商:MOTOROLA 制造商全稱:Motorola, Inc 功能描述:High-Frequency, High-Current, Self-Protected High-Side Switch (4.0 mз up to 60 kHz) |
| PC33984CHFKR2 | 制造商:Freescale Semiconductor 功能描述: |
| PC33989DW | 制造商:MOTOROLA 制造商全稱:Motorola, Inc 功能描述:System Basis Chip with High Speed CAN Transceiver |
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