MLX90277

Dual Programmable Linear Hall Effect Sensor

3901090277

Page 9 of 21

Data Sheet

Rev 004

Nov/06

The MLX90277 sensors also have an additional stage, Fine Gain, for fine tuning the Sensitivity. The stage

(parameter FG) follows the RG and provides a 10 bit adjustment. The small signal gain of the FG is within

1.0 and 2.5. The RG and FG parameters are adjusted in the application to calibrate the sensitivity (gain) and

output slope transfer characteristic of the device. The function for the fine gain is given in the following

equation:

1023

*

6

.

0

1

1

FG

Gain

Fine

−

=

Note. The one bit parameter INVERT is used to fix the “sign” of the sensitivity. A value of 0 makes the gain

positive and the output voltage increases in response to a South magnetic field. A value of 1 makes the gain

negative and the output voltage decrease in response to a South magnetic field. Refer to section 10.5,

Sensitivity Polarity for more information on INVERT.

10.4 Sensitivity Range Selection

Each unit is characterized over temperature during final test to optimize its performance and accuracy. To

achieve the best possible Sensitivity Temperature Compensation, TempCo., each unit is optimized for use

within a specific Sensitivity range. This is represented in the ordering information by the option code. There

are four available ranges, option codes 0, 1, 2 and 3. The option code corresponds with the two MSB of the

RG parameter. Each device is tested to meet the TempCo specification in the Sensitivity range determined

by the RG parameter (RG = 0…3, RG = 4…7, RG = 8...11 or RG = 12…15), regardless of the FG parameter.

The Sensitivity range is selected independently for Sensor A and Sensor B. Melexis may limit the available

combinations.

Option Code

Rough Gain

Sensitivity Range

(mV/mT)

Typical Magnetic Field Range

0

0-3 (00 xx)

2.6 < S < 15

333 < B < 800

1

4-7 (01 xx)

10 < S < 35

156 < B < 333

2

8-11 (10 xx)

18 < S < 90

62 < B < 156

3

12-15 (11 xx)

50 < S < 210

6 < B < 62

Table 9: Optimized Sensitivity Range

The next figures show the typical Sensitivity versus the FG and RG parameters. The gray areas are

representative of the chip to chip dispersion (i.e.: for the same RG and FG parameters, the Sensitivity can

vary from chip to chip). There is large overlap between the different ranges for use of one range for

applications with large magnetic and/or mechanical dispersions. The Sensitivity graphs and tables can be

used to select the right device type for the application. If one is unsure of the application’s magnetic design

and the desired Sensitivity range Melexis recommends option code 2.