Precision Programmable
Linear Hall Effect Sensor
MLX90215
How does it Work?
The MLX90215 programming is done through the
output pin, by changing supply voltage levels. Please
note that the V
DD
is raised to approximately 13V and
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.
Programming The Quiescent Offset Voltage (V
OQ
)10
bits, 1024 steps of resolution, are allotted to adjust the
Quiescent Offset Voltage (V
OQ
). By utilizing the
HALFVDD function, the V
OQ
can be set to one of two
ranges. With the HALFVDD function disabled, the V
OQ
can be programmed within a range of 10% to 90% V
DD
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.
Table 2 - Programming Sensitivity
RoughGain
0
0
1
1
2
2
3
3
FineGain
0
1023
0
1023
0
1023
0
1023
0
1023
0
1023
0
1023
0
1023
Output
4.1
9.4
6.2
14.6
9.5
22.4
14.2
33.1
21.5
50.4
31.3
72.5
46.2
107
68.9
140
Units
mV/mT
mV/mT
mV/mT
mV/mT
mV/mT
mV/mT
mV/mT
mV/mT
mV/mT
mV/mT
mV/mT
mV/mT
mV/mT
mV/mT
mV/mT
mV/mT
9/09/03
Table 1 - Programming Offset Voltage (V
OQ
)
HalfVDD
0
0
0
1
1
1
3901090215
Rev 007
4
4
5
5
6
6
7
7
Page 3
OffsetDAC
0
512
1023
0
512
1023
Output
4.97
2.47
0.03
3.07
2.45
1.83
Units
V
V
V
V
V
V
MELEXIS [ Melexis Microelectronic Systems ]
