HAL880 datasheet(8/34 Pages) MICRONAS

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HAL880

DATA SHEET

Feb. 23, 2009; DSH000152_001EN

Micronas

2.2. Digital Signal Processing and EEPROM

The DSP is the main part of this sensor and performs

the signal conditioning. The parameters for the DSP

are stored in the EEPROM registers. The details are

shown in Fig. 2–3 on page 7.

Terminology:

SENSITIVITY: name of the register or register value

Sensitivity:

name of the parameter

The EEPROM registers consist of four groups:

Group 1 contains the registers for the adaption of the

sensor to the magnetic system: MODE for selecting

the magnetic field range and filter frequency, TC,

TCSQ and TC-range for the temperature characteris-

tics of the magnetic sensitivity.

Group 2 contains the registers for defining the output

characteristics: SENSITIVITY, VOQ, CLAMP-LOW,

and CLAMP-HIGH. The output characteristic of the

sensor is defined by these 4 parameters.

– The parameter VOQ (Output Quiescent Voltage) cor-

responds to the output voltage at B = 0 mT.

– The parameter Sensitivity defines the magnetic sen-

sitivity:

– The output voltage can be calculated as:

The output voltage range can be clamped by setting

the registers CLAMP-LOW and CLAMP-HIGH in order

to enable failure detection (such as short-circuits to

VDD or GND and open connections).

Group 3 contains the general purpose register GP.

The GP register can be used to store customer infor-

mation, like a serial number after manufacturing.

Micronas will use this GP REGISTER to store informa-

tion such as lot number, wafer number, x and y posi-

tion of the die on the wafer, etc. This information can

be readout by the customer and stored in its own data

base or it can stay in the sensor as it is.

Group 4 contains the Micronas registers and LOCK

for the locking of all registers. The Micronas registers

are programmed and locked during production. These

registers are used for oscillator frequency trimming,

A/D converter offset compensation, and several other

special settings.

An external magnetic field generates a Hall voltage

on the Hall plate. The ADC converts the amplified

positive or negative Hall voltage (operates with mag-

netic north and south poles at the branded side of the

package) to a digital value. The digital signal is

filtered in the internal low-pass filter and manipulated

according to the settings stored in the EEPROM. The

digital value after signal processing is readable in the

D/A-READOUT register. Depending on the program-

mable magnetic range of the Hall IC, the operating

range of the A/D converter is from

−30 mT … +30 mT

up to

−100 mT … +100 mT.

During further processing, the digital signal is multi-

plied with the sensitivity factor, added to the quiescent

output voltage and limited according to the clamping

voltage. The result is converted to an analog signal

and stabilized by a push-pull output transistor stage.

The D/A-READOUT at any given magnetic field

depends on the programmed magnetic field range, the

low-pass

filter,

values,

CLAMP-LOW

and

CLAMP-HIGH. The D/A-READOUT range is min. 0

and max. 16383.

Note: During application design, it should be taken

into consideration that the maximum and mini-

mum D/A-READOUT should not saturate in the

operational range of the specific application.

Range

The RANGE bits are bit 2 and 3 of the MODE register;

they define the magnetic field range of the A/D

converter.

Sensitivity

OUT

-----------------

OUT

Sensitivity

∼

Magnetic Field Range

RANGE

−30mT...30 mT

−60 mT...60 mT

−80 mT...80 mT

−100 mT...100 mT

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