MLX90215_12 Datasheet, PDF (4/14 Pages) Melexis Microelectronic Systems – Position Programmable Linear Hall Effect Sensor

MLX90215
Position Programmable
Linear Hall Effect Sensor
Notes:
(1) If output current and voltage specifications are exceeded, linearity will be degraded.
(2) If VOQ is programmed beyond these limits, the temperature compensation may become a problem at high
temperatures. It is not recommended to program values of VOQ below 1V or above 4V when sensitivity exceeds 100
mV/mT. Temperature instability can occur on some devices under these conditions.
(3) Bandwidth is related to the sample rate and ROUGHGAIN. Bandwidth is estimated by (sample rate / 30)
(4) Peak to Peak Noise is a function of ROUGHGAIN setting. See page 5, Peak to Peak Noise versus Sensitivity.
(5) Sensitivity drift is independent of other parameters and does not include individual tolerances (∆VOQ or ∆VOQ/∆T).
The tolerance for sensitivity ±1% of its initial value. This does not include tolerance stack-up.
(6) If the step input occurs in the middle of a sample interval, the small signal response delay will double. For
ROUGHGAIN values less than or equal to 3, response time may be limited by the slew rate.
(7) 1 mT = 10 Gauss
Melexis Inc. reserves the right to make changes without further notice to any products herein to improve reliability, function, or design. Melexis does not
assume any liability arising from the use of any product or application of any product or circuit described herein.
4 How does it work?
The MLX90215 programming is done through the output pin, by changing supply voltage levels. Please
note that the VDD 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 (VOQ)10 bits, 1024 steps of resolution, are allotted to adjust the
Quiescent Offset Voltage (VOQ). By utilizing the HALFVDD function, the VOQ can be set to one of two ranges. With the
HALFVDD function disabled, the VOQ can be programmed within a range of 10% to 90% VDD 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.
3901090215
Rev 008
Page 4 of 14
Nov/12