MLX90215

Precision Programmable

Linear Hall Effect Sensor

3901090215

Page 3

9/09/03

Rev 007

HowdoesitWork?

The MLX90215 programming is done through the

output pin, by changing supply voltage levels. Please

18V during programming. Any connected components

must also tolerate this voltage excursion. When the

supply voltage is at 4.5V to 5.5V, the output behaves

normally. If the supply voltage is raised to 13V, the

output then behaves as an input, or LOAD mode,

allowing the 37-bit word to be clocked in. All data is

loaded through a single line, with no dedicated clock

signal. Clock and data are integrated into one signal

which is initiated with the beginning of the LOAD

sequence, then clocked with the positive edge of each

bit. Variables are changed with the PC software and

loaded into the temporary register of the device (RAM)

via the timings of the programmer’s microcontroller.

Data can be loaded as many times as desired while in

LOAD mode. Once a word is loaded, results are

checked by observing the output voltage. This can be

done with an external Voltmeter attached directly to pin

4 of the device, or with the internal ADC of the

programmer. Once the desired program is loaded, the

word can be “Zapped” permanently into ROM.

This is done when the supply voltage rises above 18V,

or ZAP mode, creating enough current to “Zap” 31

zener diodes which correspond to the temporary

register. The ZAP function is a one-time function and

cannot be erased.

The above description is only for reference. The voltage

levels and data transfer rates are completely controlled

by the ASIC programmer. For more information on the

programmer hardware, contact Melexis and request a

datasheet for the SDAP programmer.

bits, 1024 steps of resolution, are allotted to adjust the

with

about

5mV

per

step

resolution.

With

the

HALFVDD function enabled, the device may be

programmed within a 2V to 3V window with less than

1mV per step resolution

Programming the Sensitivity (Gain)

The sensitivity is programmed with a ROUGHGAIN

and a FINEGAIN adjustment. The ROUGHGAIN is

adjusted by utilizing three bits, or 8 increments. The

FINEGAIN is programmed with 10 bits or 1024

increments. The sensitivity can be programmed within a

range of 5mV/mT to 140mV/mT. Another 1-bit function

allows the direction of the sensitivity to be reversed.

The INVERTSLOPE function, when activated, will

cause the Voltage output of the MLX90215 to decrease

in the presence of a South magnetic field, and to

increase in the presence of a North magnetic field. Table

2 expresses examples of sensitivity resulting from

programming ROUGH GAIN and FINE GAIN codes,

with the INVERT SLOPE function turned off.

Note: Tables 1 and 2 are examples how various codes affect the device.

Output voltage will vary slightly from device to device. Use these tables

for reference only.

Units

HalfVDD

OffsetDAC

Output

0

0

0

1

1

1

0

512

1023

0

512

1023

4.97

2.47

0.03

3.07

2.45

1.83

V

V

V

V

V

V

Table 1 - Programming Offset Voltage (V

RoughGain

FineGain

Output

Units

0

0

1

1

2

2

0

1023

1023

0

4.1

9.4

6.2

14.6

9.5

22.4

mV/mT

Table 2 - Programming Sensitivity

mV/mT

mV/mT

mV/mT

mV/mT

mV/mT

3

3

4

4

5

5

0

1023

1023

0

14.2

33.1

21.5

50.4

31.3

72.5

mV/mT

mV/mT

mV/mT

mV/mT

mV/mT

mV/mT

6

6

46.2

107

mV/mT

mV/mT

7

7

68.9

140

mV/mT

mV/mT

0

1023

0

1023

0

1023

0

1023