MLX90251_12 Datasheet, PDF (12/20 Pages) Melexis Microelectronic Systems – Programmable Linear Hall Effect Sensor

MLX90251
Programmable Linear Hall Effect Sensor
10.5 Sensitivity Polarity (INVERT)
The slope transfer characteristic defines the Sensitivity. The INVERT parameter changes the Sensitivity's
polarity, or the slope's direction. This allows the device to accommodate the application requirements and
the magnet's polarity. The slope is inverted in the first stage of the IC, at the Hall plate. With INVERT set to 0,
the output voltage increases as a South magnetic field is applied and decreases in the presence of a North
magnetic field. An INVERT value of 1 causes the output voltage to increase in the presence of a North
magnetic field and decrease in the presence of a South magnetic field. The magnetic field polarity is
referenced to the field component perpendicular to the top-face of the MLX90251.
10.6 Clamping Levels (CLAMPLOW, CLAMPHIGH)
Two independent values, called the clamping levels, can limit the output voltage range or swing. The
CLAMPLOW parameter adjusts the minimum output voltage level, ClampLo. The CLAMPHIGH sets the
maximum output voltage level, ClampHi. Both parameters have 10 bits of adjustment with a resolution of
approximately 0.005V. The formulas below give a close approximation of the output clamp voltage. The
actual clamping level formulas vary slightly from chip to chip. If CLAMPLOW exceeds CLAMPHIGH the
output voltage is fixed at the high clamp voltage level. The CLAMPHIGH and CLAMPLOW have an initial
value of 512, set by Melexis. This results in a fixed output voltage of approximately 50% V_DD.
5.10V
ClampLo =
∗ CLAMPLOW
1023
V_DD =5.00V
5.10V
ClampHi =
∗ CLAMPHIGH
1023
V_DD =5.00V
At the point the output voltage switches between the linear operating region and the clamping region the
output can deviate slightly. This is represented by the grey areas in the figure below. The limits for deviation
in the Y axis are listed in Table 10. The deviation in the X axis is calculated from the application's transfer
function. The Clamp Comparator Offset does not affect the output linearity or clamp voltage accuracy.
During calibration it is recommended to set the clamp voltage outside of the transition region (0V to 5V).
VOUT
CLAMP HIGH
Linear Operating
Region
CLAMP LOW
Transition Point
FIELD
Figure 10.6 Output Voltage Clamping Deviation
DC operating parameters at V_DD = 5V (unless otherwise specified) and for T_A as specified by the temperature
range (E or L).
Parameter
Clamp Comparator Offset
Symbol Test Conditions
Min Typical Max
CLAMP_OFF
- 0.7
+ 0.7
Table 10: Clamp Comparator Offset Specification
Units
%VDD
3901090251
Rev 012
Page 12 of 20
Data Sheet
Oct/2012