HAL320 datasheet(6/22 Pages) MICRONAS

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HAL320

DATA SHEET

Micronas

2. Functional Description

This Hall effect sensor is a monolithic integrated circuit

with 2 Hall plates 2.25 mm apart that switches in re-

sponse to differential magnetic fields. If magnetic fields

with flux lines perpendicular to the sensitive areas are

applied to the sensor, the biased Hall plates force Hall

voltages proportional to these fields. The difference of

the Hall voltages 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 differential

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 the output without oscillation.

Magnetic offset caused by mechanical stress at the Hall

plates is compensated for by using the “switching offset

compensation technique”: An internal oscillator pro-

vides a two phase clock (see Fig. 2–2). The difference

of the Hall voltages is sampled at the end of the first

phase. At the end of the second phase, both sampled

differential Hall voltages are averaged and compared

with the actual switching point. Subsequently, the open

drain output switches to the appropriate state. The

amount of time that elapses from crossing the magnetic

switch level to the actual switching of the 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 re-

sistors. 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 values

ranging from 0 V to –15 V.

HAL 320

Temperature

Dependent

Bias

Switch

Hysteresis

Control

Comparator

Output

VDD

OUT

Clock

GND

Fig. 2–1: HAL 320 block diagram

Short Circuit &

Overvoltage

Protection

Reverse

Voltage &

Overvoltage

Protection

Hall Plate

VOL

VOUT

1/fosc = 16 μs

Fig. 2–2: Timing diagram

VOH

DBON

fosc

IDD

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