HAL2XY datasheet(6/17 Pages) MICRONAS

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HAL 2xy

DATA SHEET

Jan. 11, 2010; DSH000141_003EN

Micronas

2. Functional Description

The Hall effect sensor is a monolithic integrated circuit

that switches in response to magnetic fields. If a mag-

netic 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 induc-

tion of magnets at higher temperatures. If the magnetic

field exceeds the threshold levels, the open drain

output switches to the appropriate state. The built-in

hysteresis eliminates oscillation and provides switch-

ing behavior of output without bouncing.

Magnetic offset caused by mechanical stress is com-

pensated for by using the “switching offset compensa-

tion technique”. Therefore, an internal oscillator pro-

vides a two phase clock. The Hall voltage is sampled

at the end of the first phase. At the end of the second

phase, both sampled and actual Hall voltages are

averaged and compared with the actual switching

point. Subsequently, the open drain output switches to

the appropriate state. The time from crossing the mag-

netic switching level to switching of output can vary

between zero and 1/fosc.

Shunt protection devices clamp voltage peaks at the

Output pin and VDD-pin together with external series

resistors. Reverse current is limited at the VDD-pin by

an internal series resistor up to

−15 V. No external

reverse protection diode is needed at the VDD-pin for

reverse voltages ranging from 0 V to

−15 V.

In case of HAL22y a built-in reset-circuit clamps the

output to the “high” state (reset state) during power-on

or when the supply voltage drops below the reset volt-

age of Vreset < 4.3 V. For supply voltages between

Vreset and 4.3 V, the output state of the device

responds to the magnetic field. For supply voltages

above 4.3 V, the device works according to the speci-

fied characteristics.

Fig. 2–1: HAL20y and HAL 21y block diagram

Fig. 2–2: HAL22y block diagram

Reverse

Voltage &

Overvoltage

Protection

Temperature

Dependent

Bias

Hysteresis

Control

Short Circuit

and

Overvoltage

Hall Plate

Switch

Comparator

Output

Clock

Protection

OUT

GND

VDD

Temperature

Dependent

Bias

Switch

Hysteresis

Control

Comparator

Output

VDD

OUT

Clock

Hall Plate

GND

Power-on &

Undervoltage

Reset

Short Circuit &

Overvoltage

Protection

Reverse

Voltage &

Overvoltage

Protection

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