HAL815, Programmable Linear Hall Sensor

ADVANCE INFORMATION

HAL 815

Micronas

Programmable Linear Hall Effect Sensor

1. Introduction

The HAL 815 is a new member of the Micronas family

of programmable linear Hall sensors. As an extension

to the HAL 800, it offers open-circuit, as well as over-

voltage and undervoltage detection and individual pro-

gramming of different sensors which are in parallel to

the same supply voltage.

The HAL 815 is an universal magnetic field sensor with

a linear output based on the Hall effect. The IC is

designed and produced in sub-micron CMOS technol-

ogy and can be used for angle or distance measure-

ments if combined with a rotating or moving magnet.

The major characteristics like magnetic field range,

sensitivity, output quiescent voltage (output voltage at

B = 0 mT), and output voltage range are programma-

ble in a non-volatile memory. The sensor has a ratio-

metric output characteristic, which means that the out-

put voltage is proportional to the magnetic flux and the

supply voltage.

The HAL 815 features a temperature-compensated

Hall plate with choppered offset compensation, an A/D

converter, digital signal processing, a D/A converter

with output driver, an EEPROM memory with redun-

dancy and lock function for the calibration data, a

serial interface for programming the EEPROM, and

protection devices at all pins. The internal digital signal

processing is of great benefit because analog offsets,

temperature shifts, and mechanical stress do not

degrade the sensor accuracy.

The HAL 815 is programmable by modulating the sup-

ply voltage. No additional programming pin is needed.

The easy programmability allows a 2-point calibration

by adjusting the output voltage directly to the input sig-

nal (like mechanical angle, distance, or current). Indi-

vidual adjustment of each sensor during the cus-

tomer’s manufacturing process is possible. With this

calibration procedure, the tolerances of the sensor, the

magnet, and the mechanical positioning can be com-

pensated in the final assembly. This offers a low-cost

alternative for all applications that presently need

mechanical adjustment or laser trimming for calibrating

the system.

In addition, the temperature compensation of the Hall

IC can be fit to all common magnetic materials by pro-

gramming first and second order temperature coeffi-

cients of the Hall sensor sensitivity. This enables oper-

ation over the full temperature range with high

accuracy.

The calculation of the individual sensor characteristics

and the programming of the EEPROM memory can

easily be done with a PC and the application kit from

Micronas.

The sensor is designed for hostile industrial and auto-

motive applications and operates with typically 5 V

supply voltage in the ambient temperature range from

−

40 °C up to 150 °C. The HAL 815 is available in the

very small leaded package TO-92UT.

1.1. Major Applications

Due to the sensor’s versatile programming character-

istics, the HAL 815 is the optimal system solution for

applications such as:

– contactless potentiometers,

– angle sensors,

– distance measurements,

– magnetic field and current measurement.

1.2. Features

– high-precision linear Hall effect sensor with

ratiometric output and digital signal processing

– multiple programmable magnetic characteristics in a

non-volatile memory (EEPROM) with redundancy

and lock function

– open-circuit (ground and supply line break detec-

tion), overvoltage and undervoltage detection

– for programming an individual sensor within several

sensors in parallel to the same supply voltage, a

selection can be done via the output pin

– to enable programming of an individual sensor

amongst several sensors running parallel to the

same supply voltage, each sensor can be selected

via its output pin

– temperature characteristics are programmable for

matching all common magnetic materials

– programmable clamping function

– programming through a modulation of the supply

voltage

– operates from

−

40 °C up to 150 °C

ambient temperature

– operates from 4.5 V up to 5.5 V supply voltage in

specification and functions up to 8.5 V

– total error < 2.0% over operating voltage range and

temperature range

– operates with static magnetic fields and dynamic

magnetic fields up to 2 kHz

– overvoltage and reverse-voltage protection at all pins

– magnetic characteristics extremely robust against

mechanical stress

– short-circuit protected push-pull output

– EMC and ESD optimized design

HAL 815

ADVANCE INFORMATION

Micronas

1.3. Marking Code

The HAL 815 has a marking on the package surface

(branded side). This marking includes the name of the

sensor and the temperature range.

1.4. Operating Junction Temperature Range (T

)

The Hall sensors from Micronas are specified to the

chip temperature (junction temperature T

A: TJ =

−

40 °C to +170 °C

K: TJ =

−

40 °C to +140 °C

E: TJ =

−

40 °C to +100 °C

The relationship between ambient temperature (T

)

and junction temperature is explained in Section 4.5.

on page 18.

1.5. Hall Sensor Package Codes

Example: HAL815UT-K

→

Type:

815

→

Package:

TO-92UT

→

Temperature Range:

−

40°C to +140°C

Hall sensors are available in a wide variety of packag-

ing versions and quantities. For more detailed informa-

tion, please refer to the brochure: “Ordering Codes for

Hall Sensors”.

1.6. Solderability

Package TO-92UT: according to IEC68-2-58

During soldering reflow processing and manual

reworking, a component body temperature of 260 °C

should not be exceeded.

Components stored in the original packaging should

provide a shelf life of at least 12 months, starting from

the date code printed on the package labels, even in

environments as extreme as 40 °C and 90% relative

humidity.

1.7. Pin Connections and Short Descriptions

Fig. 1–1: Pin configuration

Type

Temperature Range

HAL 815

815A

815K

815E

HALXXXPA-T

Temperature Range: A, K, or E

Package: UT for TO-92UT

Type: 815

Pin

No.

Pin Name

Type

Short Description

Supply Voltage and

Programming Pin

GND

Ground

OUT

Push Pull Output

and Selection Pin

OUT

GND

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HAL 815

Micronas

2. Functional Description

2.1. General Function

The HAL 815 is a monolithic integrated circuit which

provides an output voltage proportional to the mag-

netic flux through the Hall plate and proportional to the

supply voltage (ratiometric behavior).

The external magnetic field component perpendicular

to the branded side of the package generates a Hall

voltage. The Hall IC is sensitive to magnetic north and

south polarity. This voltage is converted to a digital

value, processed in the Digital Signal Processing Unit

(DSP) according to the settings of the EEPROM regis-

ters, converted to an analog voltage with ratiometric

behavior, and stabilized by a push-pull output transis-

tor stage. The function and the parameters for the DSP

are explained in Section 2.2. on page 7.

The setting of the LOCK register disables the program-

ming of the EEPROM memory for all time. This regis-

ter cannot be reset.

As long as the LOCK register is not set, the output

characteristic can be adjusted by programming the

EEPROM registers. The IC is addressed by modulat-

ing the supply voltage (see Fig. 2–1). In the supply

voltage range from 4.5 V up to 5.5 V, the sensor gener-

ates an analog output voltage. After detecting a com-

mand, the sensor reads or writes the memory and

answers with a digital signal on the output pin. The

analog output is switched off during the communica-

tion.

Several sensors in parallel to the same supply and

ground line can be programmed individually. The

selection of each sensor is done via its output pin.

The open-circuit detection provides a defined output

voltage if the V

or GND line is broken. Internal tem-

perature compensation circuitry and the choppered off-

set compensation enables operation over the full tem-

perature range with minimal changes in accuracy and

high offset stability. The circuitry also rejects offset

shifts due to mechanical stress from the package. The

non-volatile memory consists of redundant EEPROM

cells. In addition, the sensor IC is equipped with

devices for overvoltage and reverse-voltage protection

at all pins.

Fig. 2–1: Programming with V

modulation

Fig. 2–2: HAL 815 block diagram

)

HAL

815

GND

OUT

analog

digital

Internally

Temperature

Oscillator

Switched

100

Ω

Digital

D/A

Analog

OUT

GND

Supply

EEPROM Memory

Lock Control

Digital

stabilized

Supply and

Protection

Devices

Dependent

Bias

Protection

Devices

Hall Plate

Signal

Processing

Converter

Output

Level

Detection

Output

A/D

Converter

10 k

Ω

Open-circuit,

Overvoltage,

Undervoltage

Detection

HAL 815

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Micronas

Fig. 2–3: Details of EEPROM and Digital Signal Processing

MODE Register

FILTER

6 bit

TCSQ

5 bit

SENSI-

14 bit

VOQ

11 bit

CLAMP-

10 bit

11 bit

LOCKR

1 bit

3 bit

RANGE

3 bit

EEPROM Memory

A/D

Converter

Digital

Filter

Multiplier

Adder

Limiter

D/A

Converter

Digital Signal Processing

ADC-READOUT Register

14 bit

Digital

Lock

Control

TIVITY

LOW

CLAMP-

HIGH

Output

Micronas

Registers

–40

–20

40 mT

OUT

Clamp-high = 4 V

Sensitivity = 0.116

= 2.5 V

Clamp-low = 1 V

Range = 30 mT

Filter = 500 Hz

Fig. 2–4: Example for output characteristics

–150 –100

–50

100

150 mT

OUT

Clamp-high = 4.5 V

Sensitivity = –1.36

= –0.5 V

Clamp-low = 0.5 V

Range = 100 mT

Filter = 2 kHz

Fig. 2–5: Example for output characteristics

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HAL 815

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.

Terminology:

SENSITIVITY: name of the register or register value

Sensitivity:

name of the parameter

The EEPROM registers consist of three 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 and

TCSQ for the temperature characteristics of the mag-

netic 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 (see Fig. 2–4

and Fig. 2–5 for examples).

– The parameter V

(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

or GND and open connections).

Group 3 contains the Micronas registers and LOCK for

the locking of all registers. The Micronas registers are

programmed and locked during production and are

read-only for the customer. 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 magnetic north

and south poles at the branded side of the package) to

a digital value. Positive values correspond to a mag-

netic north pole on the branded side of the package.

The digital signal is filtered in the internal low-pass fil-

ter and is readable in the ADC-READOUT register.

Depending on the programmable magnetic range of

the Hall IC, the operating range of the A/D converter is

from

−

30 mT...+30 mT up to

−

150 mT...+150 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 ADC-READOUT at any given magnetic field

depends on the programmed magnetic field range but

also on the filter frequency. Fig. 2–6 shows the typical

ADC-READOUT values for the different magnetic field

ranges with the filter frequency set to 2 kHz. The rela-

tionship between the minimum and maximum ADC-

READOUT values and the filter frequency setting is

listed in the following table.

∆

OUT

∆

Sensitivity =

OUT

∼

Sensitivity

B + V

Filter Frequency

ADC-READOUT RANGE

80 Hz

−

3968...3967

160 Hz

−

1985...1985

500 Hz

−

5292...5290

1 kHz

−

2646...2645

2 kHz

−

1512...1511

–2000

–1500

–1000

–500

500

1000

1500

2000

–200–150–100 –50

50 100 150 200 mT

ADC-

READOUT

Range 150 mT

Filter = 2 kHz

Range 90 mT

Range 60 mT

Range 30 mT

Fig. 2–6: Typical ADC-READOUT

versus magnetic field for filter = 2 kHz

HAL 815

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Micronas

Note: During application design, it should be taken

into consideration that the maximum and minimum

ADC-READOUT is not exceeded during calibration

and operation of the Hall IC. Consequently, the maxi-

mum and minimum magnetic fields that may occur in

the operational range of a specific application should

not saturate the A/D converter. Please note that the

A/D converter saturates at magnetic fields well above,

respectively below, the magnetic range limits. This

large safety band between specified magnetic range

and true operational range helps to avoid any satura-

tion.

Range

The RANGE bits are the three lowest bits of the MODE

A/D converter.

Filter

The FILTER bits are the three highest bits of the

MODE register; they define the

−

3 dB frequency of the

digital low pass filter.

TC and TCSQ

The temperature dependence of the magnetic sensitiv-

ity can be adapted to different magnetic materials in

order to compensate for the change of the magnetic

strength with temperature. The adaption is done by

programming the TC (Temperature Coefficient) and

the TCSQ registers (Quadratic Temperature Coeffi-

cient). Thereby, the slope and the curvature of the tem-

perature dependence of the magnetic sensitivity can

be matched to the magnet and the sensor assembly.

As a result, the output voltage characteristic can be

fixed over the full temperature range. The sensor can

compensate for linear temperature coefficients ranging

from about

−

3100 ppm/K up to 400 ppm/K and qua-

dratic coefficients from about

−

5 ppm/K² to 5 ppm/K².

Please refer to Section 4.3. on page 17 for the recom-

mended settings for different linear temperature coeffi-

cients.

Sensitivity

The SENSITIVITY register contains the parameter for

the multiplier in the DSP. The Sensitivity is program-

mable between

−

4 and 4. For V

= 5 V, the register

can be changed in steps of 0.00049. Sensitivity = 1

corresponds to an increase of the output voltage by

if the ADC-READOUT increases by 2048.

For all calculations, the digital value from the magnetic

field of the A/D converter is used. This digital informa-

tion is readable from the ADC-READOUT register.

VOQ

The VOQ register contains the parameter for the adder

in the DSP. V

is the output voltage without external

magnetic field (B = 0 mT, respectively ADC-READOUT

= 0) and programmable from

−

up to V

. For V

= 5 V, the register can be changed in steps of 4.9 mV.

Note: If V

is programmed to a negative voltage, the

maximum output voltage is limited to:

For calibration in the system environment, a 2-point

adjustment procedure (see Section 2.3.) is recom-

mended. The suitable Sensitivity and V

values for

each sensor can be calculated individually by this pro-

cedure.

Magnetic Field Range

RANGE

−

30 mT...30 mT

−

40 mT...40 mT

−

60 mT...60 mT

−

75 mT...75 mT

−

80 mT...80 mT

−

90 mT...90 mT

−

100 mT...100 mT

−

150 mT...150 mT

−

3 dB Frequency

FILTER

80 Hz

160 Hz

500 Hz

1 kHz

2 kHz

∆

OUT

* 2048

∆

ADC-READOUT * V

Sensitivity =

OUTmax

= V

+ V

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HAL 815

Micronas

Clamping Voltage

The output voltage range can be clamped in order to

detect failures like shorts to V

or GND or an open

circuit.

The CLAMP-LOW register contains the parameter for

the lower limit. The lower clamping voltage is program-

mable between 0 V and V

/2. For V

= 5 V, the reg-

ister can be changed in steps of 2.44 mV.

The CLAMP-HIGH register contains the parameter for

the upper limit. The upper clamping voltage is pro-

grammable between 0 V and V

. For V

= 5 V, in

steps of 2.44 mV.

LOCKR

By setting this 1-bit register, all registers will be locked,

and the sensor will no longer respond to any supply

voltage modulation.

Warning: This register cannot be reset!

ADC-READOUT

This 14-bit register delivers the actual digital value of

the applied magnetic field before the signal process-

ing. This register can be read out and is the basis for

the calibration procedure of the sensor in the system

environment.

2.3. Calibration Procedure

2.3.1. General Procedure

For calibration in the system environment, the applica-

tion kit from Micronas is recommended. It contains the

hardware for the generation of the serial telegram for

programming and the corresponding software for the

input of the register values.

In this section, programming of the sensor using this

programming tool is explained. Please refer to

Section 5. on page 19 for information about program-

ming without this tool.

For the individual calibration of each sensor in the cus-

tomer application, a two point adjustment is recom-

mended (see Fig. 2–7 for an example). When using

the application kit, the calibration can be done in three

steps:

Step 1: Input of the registers which need not be

adjusted individually

The magnetic circuit, the magnetic material with its

temperature characteristics, the filter frequency, and

low and high clamping voltage are given for this appli-

cation.

Therefore, the values of the following registers should

be identical for all sensors of the customer application.

– FILTER

(according to the maximum signal frequency)

– RANGE

(according to the maximum magnetic field at the

sensor position)

– TC and TCSQ

(depends on the material of the magnet and the

other temperature dependencies of the application)

– CLAMP-LOW and CLAMP-HIGH

(according to the application requirements)

Write the appropriate settings into the HAL 815 regis-

ters.

HAL 815

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Micronas

Step 2: Calculation of V

and Sensitivity

The calibration points 1 and 2 can be set inside the

specified range. The corresponding values for V

OUT1

and V

OUT2

result from the application requirements.

For highest accuracy of the sensor, calibration points

near the minimum and maximum input signal are rec-

ommended. The difference of the output voltage

between calibration point 1 and calibration point 2

should be more than 3.5 V.

Set the system to calibration point 1 and read the reg-

ister ADC-READOUT. The result is the value ADC-

READOUT1.

Now, set the system to calibration point 2, read the

ADC-READOUT2.

With these values and the target values V

OUT1

and

OUT2

, for the calibration points 1 and 2, respectively,

the values for Sensitivity and V

are calculated as:

This calculation has to be done individually for each

sensor.

Next, write the calculated values for Sensitivity and

into the IC for adjusting the sensor.

The sensor is now calibrated for the customer applica-

tion. However, the programming can be changed again

and again if necessary.

Step 3: Locking the Sensor

The last step is activating the LOCK function with the

“LOCK” command. The sensor is now locked and does

not respond to any programming or reading com-

mands.

Warning: This register cannot be reset!

2.3.2. Calibration of the Angle Sensor

The following description explains the calibration pro-

cedure using an angle sensor as an example. The

required output characteristic is shown in Fig. 2–7.

– the angle range is from

−

25° to 25°

– temperature coefficient of the magnet:

−

500 ppm/K

Step 1: Input of the registers which need not be

adjusted individually

The register values for the following registers are given

for all applications:

– FILTER

Select the filter frequency: 500 Hz

– RANGE

Select the magnetic field range: 30 mT

– TC

For this magnetic material: 6

– TCSQ

For this magnetic material: 14

– CLAMP-LOW

For our example: 0.5 V

– CLAMP-HIGH

For our example: 4.5 V

Enter these values in the software, and use the “write

and store” command for permanently writing the val-

ues in the registers.

Low clamping voltage

≤

OUT1,2

≤

High clamping voltage

OUT1

−

OUT2

ADC-READOUT1

−

ADC-READOUT2

Sensitivity =

2048

ADC-READOUT1 * Sensitivity * V

2048

= V

OUT1

−

–30

–20

–10

Angle

OUT

Clamp-high = 4.5 V

Clamp-low = 0.5 V

Calibration point 2

Calibration point 1

Fig. 2–7: Example for output characteristics