HAL320 datasheet(20/22 Pages) MICRONAS

20 / 22 page

HAL320

DATA SHEET

Micronas

4. Application Notes

Mechanical stress can change the sensitivity of the Hall

plates and an offset of the magnetic switching points

may result. External mechanical stress on the sensor

must be avoided if the sensor is used under back-biased

conditions. This piezo sensitivity of the sensor IC cannot

be completely compensated for by the switching offset

compensation technique.

In order to assure switching the sensor on and off in a

back-biased application, the minimum magnetic modu-

lation of the differential field should amount to more than

10% of the magnetic preinduction.

If the HAL 320 sensor IC is used in back-biased applica-

tions, please contact our Application Department. They

will provide assistance in avoiding applications which

may induce stress to the ICs. This stress may cause

drifts of the magnetic parameters indicated in this data

sheet.

4.1. Ambient Temperature

Due to the internal power dissipation, the temperature

on the silicon chip (junction temperature TJ) is higher

than the temperature outside the package (ambient tem-

perature TA).

TJ = TA + ΔT

Under static conditions and continuous operation, the

following equation applies:

ΔT = IDD * VDD * Rth

For typical values, use the typical parameters. For worst

case calculation, use the max. parameters for IDD and

Rth, and the max. value for VDD from the application.

For all sensors, the junction temperature range TJ is

specified. The maximum ambient temperature TAmax

can be calculated as:

TAmax = TJmax – ΔT

4.2. Extended Operating Conditions

All sensors fulfill the electrical and magnetic characteris-

tics when operated within the Recommended Operating

Conditions (see page 13).

Supply Voltage Below 4.5 V

Typically, the sensors operate with supply voltages

above 3 V, however, below 4.5 V some characteristics

may be outside the specification.

Note: The functionality of the sensor below 4.5 V is not

tested on a regular base. For special test condi-

tions, please contact Micronas.

4.3. Start-up Behavior

Due to the active offset compensation, the sensors have

an initialization time (enable time ten(O)) after applying

the supply voltage. The parameter ten(O) is specified in

the Electrical Characteristics (see page 13).

During the initialization time, the output state is not de-

fined and the output can toggle. After ten(O), the output

will be low if the applied magnetic field B is above BON.

The output will be high if B is below BOFF.

For magnetic fields between BOFF and BON, the output

state of the HAL sensor after applying VDD will be either

low or high. In order to achieve a well-defined output

state, the applied magnetic field must be above BONmax,

respectively, below BOFFmin.

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