mlx90251 Melexis Company, mlx90251 Datasheet - Page 12

• Manufacturer Part Number: mlx90251
• Description: Programmable Linear Hall Effect Sensor
• Manufacturer: Melexis Company

The MLX90251 includes two programmable low-pass filters located within the chopper amplifier stages. The
two low-pass filters are controlled through a 4 bit parameter, FILTER. The FILTER value 0 corresponds to
minimum filtering, maximum speed (impulse response time), and maximum output noise. The value 15
provides the maximum filtering, minimum speed, and minimum output noise. It is important to note the noise
is also linked to the gain settings.
performance. The next table shows typical values the cut-off frequency at -3 dB versus FILTER and RG
parameters. FILTER values from 8 to 11 are not used. For most applications FILTER values 7 or 15 are
recommended.
Cut-off frequency at -3 dB (Hz) – Typical
Table 11: Cut-off Frequency versus FILTER and RG Parameters
The change in the device's Sensitivity versus temperature is defined as the Sensitivity Temperature
Compensation, TempCo.
temperature. Fluctuations in temperature can cause variations in the air gap, mechanical alignment and
magnetic field. The Sensitivity Temperature Compensation feature compensates for these effects.
Three parameters, TC, TCW, TC
TempCo range, TC is for fine adjustment of the TempCo value, and TC
To simplify use of these parameters Melexis stores a look up table within the EEPROM of each device. The
look up table is optimized for each device by characterizing the unit over temperature at final test.
The value of TempCo is often determined by the magnet. In the application the TempCo is adjusted to
compensate for the temperature coefficient of the magnet. To adjust the value the look up table is read from
the device. The parameters are then calculated to match the desired value. The Melexis PTC hardware and
software tools contain built in functions for programming the TempCo.
3901090251
Rev 009
Filter
10.7 Filter (FILTER)
10.8 Sensitivity Temperature Compensation (TC, TCW, TC
10
11
12
13
14
15
0
1
2
3
4
5
6
7
8
9
MLX90251-0
Rough Gain 0…3
22900
19500
12300
10400
7450
5850
5700
5050
2200
1000
920
800
In an application the slope output transfer characteristic is often affected by
2
are used for adjustment of the TempCo. The TCW is used to adjust the
MLX90251-1
Rough Gain 4…7
The FILTER parameter needs to be adjusted to achieve optimal
14300
11450
10000
6750
3900
2900
2700
2550
840
480
380
330
Page 12 of 22
Programmable Linear Hall Effect Sensor
Not used
Not used
Not used
Not used
MLX90251-2
Rough Gain 8…11
7000
5550
3000
2100
1500
1125
1350
1380
565
470
290
250
2
effects the TempCo linear response.
2
)
MLX90251-3
Rough Gain 12…15
MLX90251
3850
2950
2300
1100
850
860
715
650
250
190
155
135
Data Sheet
Nov/06