HAL740 datasheet(20/22 Pages) MICRONAS

20 / 22 page

HAL700, HAL740

DATA SHEET

Nov. 30, 2009; DSH000029_002EN

Micronas

5. Application Notes

5.1. 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

temperature TA).

TJ = TA + ΔT

At static conditions and continuous operation, the fol-

lowing equation applies:

ΔT = I

DD * 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 appli-

cation.

For all sensors, the junction temperature range TJ is

specified. The maximum ambient temperature TAmax

can be calculated as:

TAmax = TJmax − ΔT

5.2. Extended Operating Conditions

All sensors fulfill the electrical and magnetic character-

istics when operated within the Recommended Oper-

ating Conditions (see Section 3.5. on page 11).

Supply Voltage Below 3.8 V

Typically, the sensors operate with supply voltages

above 3 V, however, below 3.8 V some characteristics

may be outside the specification.

Note: The functionality of the sensor below 3.8 V is not

tested. For special test conditions, please con-

tact Micronas.

5.3. 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 “Characteristics” (see Section 3.6. on

page 12).

During the initialization time, the output states are not

defined and the outputs can toggle. After ten(O), both

outputs will be either high or low for a stable magnetic

field (no toggling). The outputs will be low if the applied

magnetic flux density B exceeds BON and high if B

drops below BOFF.

For magnetic fields between BOFF and BON, the output

states of the Hall sensor after applying VDD will be

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

output state, the applied magnetic flux density must be

above BONmax, respectively, below BOFFmin.

5.4. EMC and ESD

For applications that cause disturbances on the supply

line or radiated disturbances, a series resistor and a

capacitor are recommended (see Fig. 5–1). The series

resistor and the capacitor should be placed as closely

as possible to the Hall sensor.

Please contact Micronas for detailed investigation

reports with EMC and ESD results.

Fig. 5–1: Test circuit for EMC investigations

1 VDD

4GND

3 S1-Output

2 S2-Output

220

VEMC

4.7 nF

2.4 k

20 pF

2.4 k

20 pF

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