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MLX90314LDF 参数 Datasheet PDF下载

MLX90314LDF图片预览
型号: MLX90314LDF
PDF下载: 下载PDF文件 查看货源
内容描述: 可编程传感器接口 [Programmable Sensor Interface]
分类和应用: 传感器
文件页数/大小: 28 页 / 798 K
品牌: MELEXIS [ Melexis Microelectronic Systems ]
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MLX90314  
Programmable Sensor Interface  
OFFSET  
Different Modes  
Analog Mode  
The parameters OF and GN represent, respectively,  
offset correction and span control, while OFTCi and  
GNTCi represent their temperature coefficients  
(thermal zero shift and thermal span shift). After reset,  
the firmware continuously calculates the offset and  
gain DAC settings as follows: The EEPROM holds  
parameters GN, OF, OFTCi and GNTCi, where “i” is  
the gap number and can be 1 < i < 4. The transfer  
function is described below.  
OF[9:0] = Fixed Gain, bytes 4 and 17 in EEPROM.  
OFTCi = Offset for a given temperature  
segment I. OFTCiL and OFTCiH in  
EEPROM table.  
dT = Temp. change within the appropriate gap.  
Calculation of the offset for a given temperature seg-  
ment is performed the same way as for the gain.  
{
Digital Mode  
I
The MLX90314 firmware provides the capability of  
digitally processing the sensor signal in addition to the  
analog processing. This capability allows for signal  
correction.  
{
FG = Hardware Gain (~72V/V). Part of the hardware  
design, and not changeable.  
CSGN = Course Gain, part of byte 2 in EEPROM.  
CSOF = Coarse Offset, part of byte 2 in  
EEPROM.  
Signal Correction  
While in digital mode the firmware can perform signal  
correction. This is an adjustment to the output level  
based on the input signal level. Adjustment  
coefficients can be set for five different signal ranges.  
The output is obtained by the following formula:  
GAIN  
GN[9:0] = Fixed Gain, bytes 3 and 17 in EEPROM.  
GNTCi = Gain TC for a given temperature  
segment I. GNTCiL and GNTCiH in  
EEPROM table.  
Output = (Signal – Pi) * Pci + Poff where  
Signal = input signal measurement;  
Poff = Pressure ordinate  
Pi = Pressure signal point (I = 2,3,4,5)  
Pci = programmed coefficient.  
dT = Temp. change within the appropriate gap.  
How to calculate gain in the first temp. gap?:  
DAC_GAIN = GN[9:0] - GNTC1 * (T1 – Temp_f1)  
How to calculate gain in the other temp. gaps?:  
The PCi coefficients are coded on 12 bits: one bit for  
the sign, one for the unity, and the rest for the  
decimals. The Pi are coded on 10 bits (0-3FFh) in  
high-low order.  
PNB_TNB: contains the number of signal points,  
coded on the four MSB’s. The four LSB’s are reserved  
for the number of temperature points. See Table 4 and  
Table 5.  
2nd gap: DAC_GAIN = GN[9:0] + GNTC2 *  
(Temp_f2 – T1)  
3th gap: DAC_GAIN = DAC_GAIN2 + GNTC3 *  
(Temp_f3 – T2)  
4th gap: DAC_GAIN = DAC_GAIN3 + GNTC4 *  
(Temp_f4 – T3)  
Where:  
Compensation Trade-Offs  
A compromise must be made between temperature  
compensation and pressure correction. The EEPROM  
space where the signal coefficients are stored is  
shared with the temperature coefficients, with the  
result that an EEPROM byte can be used either for a  
temperature coefficient or for a signal coefficient, but  
not both. Table 6 presents the possibilities among the  
maximum number of temperature gaps and the  
maximum number of signal gaps.  
Temp_f = Filtered temp. (previously described).  
If GNTC1 > 2047 => DAC_GAIN  
If GNTC2,3,4 > 2047 => DAC_GAIN  
[V/V]  
3901090314  
Page 11  
Nov/04  
Rev 007