HAL571 Datasheet, PDF (5/20 Pages) List of Unclassifed Manufacturers – Two-Wire Hall Effect Sensor Family

ADVANCE INFORMATION
HAL57x, HAL58x
2. Functional Description
The HAL 57x, HAL 58x two-wire sensors are monolithic
integrated circuits which switch in response to magnetic
fields. If a magnetic field with flux lines perpendicular to
the sensitive area is applied to the sensor, the biased
Hall plate forces a Hall voltage proportional to this field.
The Hall voltage is compared with the actual threshold
level in the comparator. The temperature-dependent
bias increases the supply voltage of the Hall plates and
adjusts the switching points to the decreasing induction
of magnets at higher temperatures.
If the magnetic field exceeds the threshold levels, the
current source switches to the corresponding state. In
the low current consumption state, the current source is
switched off and the current consumption is caused only
by the current through the Hall sensor. In the high current
consumption state, the current source is switched on
and the current consumption is caused by the current
through the Hall sensor and the current source. The
built-in hysteresis eliminates oscillation and provides
switching behavior of the output signal without bounc-
ing.
Magnetic offset caused by mechanical stress is com-
pensated for by using the “switching offset compensa-
tion technique”. An internal oscillator provides a two-
phase clock. In each phase, the current is forced through
the Hall plate in a different direction, and the Hall voltage
is measured. At the end of the two phases, the Hall volt-
ages are averaged and thereby the offset voltages are
eliminated. The average value is compared with the
fixed switching points. Subsequently, the current con-
sumption switches to the corresponding state. The
amount of time elapsed from crossing the magnetic
switching level to switching of the current level can vary
between zero and 1/f_osc.
Shunt protection devices clamp voltage peaks at the
V_DD-pin together with external series resistors. Reverse
current is limited at the V_DD-pin by an internal series
resistor up to –15 V. No external protection diode is
needed for reverse voltages ranging from 0 V to –15 V.
HAL57x, HAL58x
V_DD
Reverse
Voltage &
1
Overvoltage
Protection
Hall Plate
Temperature
Dependent
Bias
Hysteresis
Control
Switch
Comparator
Current
Source
GND
2, 3
Clock
Fig. 2–1: HAL57x, HAL 58x block diagram
f_osc
t
B
B_OFF
B_ON
t
I_DD
I_DDhigh
I_DDlow
t
I_DD
1/f_osc = 6.9 µs
t
Fig. 2–2: Timing diagram (example: HAL 581)
Micronas
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