Diodes ZMT32 User Manual

ZMT32

()

()

α

α

α

2

2

2

1

2

Tan

Cos

Sin

V

V

O

O

==

-VO1(cos)

-V

O2

(sin)

V

CC2

(bridge 2)

V

CC1

(bridge 1)

+V

O1

(cos)

+V

O2

(sin)

GND2 (bridge 2)

GND (bridge 1)

2

3

4

5

6

7

8

1

Magnetic Field Angle Sensor

Description

The ZMT32 is a thin film permalloy magnetic
field sensor, which contains two galvanic
isolated Wheatstone Bridges for high
precision angle measurement applications
under low field conditions. This angle sensor
is based on the anisotropic magnetoresistive
effect (AMR). The two internal (V

CC1

, V

CC2

bridges enclose a relative sensitive angle of
45 degrees. The input field is a rotating
magnetic field in the chip plane (parallel to
the surface of package). This rotating field will
make available two independent sinusoidal
output signals with the following relationship

()

where α = angle between sensor axis and field

direction

The precise ZMT32 works with low field
applications (H
than similar devices. The ultimate output signal
quality depends on the external magnetic
material and on the mechanical realization.

)

The ZMT32 is a passive part and the Arc­Tangent interpolation needs external signal
processing. Typical areas of application are
angle and speed measurement.

= 8 to 25kA/m), much lower

rot

Features

• contactless angle measurement up to 180°

• flexible measuring solutions for moved
systems

• stable operation over long time

• high temperature range up to +160°C

Applications

• angle and angular velocity measuring systems

• absolute angle and angle change

• automotive electronic (steering, throttle
control, pedal positioning, etc

• contactless rotary switches and potentiometer

• automatic adjustment

Ordering Information

Device Reel size

(Inches)

ZMT32TA 7 12 1,000 ZETEX

Tape w idt h

(mm)

Quantity

per reel

Device

marking

ZMT32

Issue 1 - June 2008 1 www.zetex.com

© Zetex Semiconductors plc 2008

ZMT32

Absolute maximum ratings

Parameter Symbol Limit Unit

Supply Voltages V

Single Bridge Current I

Operating Temperature

T

cc1

cc1

A

and V

or I

cc2

cc2

10 V

4 mA

-40 to +160 °C

Range

Storage Temperature

T

-55 to +175 °C

stg

Range

Recommended operating conditions

Symbol Parameter Min Typ Max Unit

V

, V

cc1

cc2

H

rot

Supply Voltages 5 8.5 V

Applied Magnetic Field Strength 8 25 kA/m

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© Zetex Semiconductors plc 2008

Electrical characteristics

NOTES:

%100

)T(

V

V

)T(

V

V

)T(

V

V

TT

1

TCV

0

CC

O

1

CC

O

2

CC

O

12

O

×

Δ

Δ

−

Δ

×

−

=

)T(

V

V

n

CC

O

Δ

General test conditions (unless otherwise noted)

TA= +23±5oC, V

CC1=VCC2

= +5V, H

ROT

=25kA/m

SYMBOL PARAMETER CONDITIONS MIN

Sα1 or S

V

PO1

or V

Sensitivities (zero crossing)

α2

Peak Output Voltages

PO2

(sinusoidal signals)

k Amplitude bridge matching 99.77 100 100.23 %

Temperature coefficient of
amplitude bridge matching

Bridge resistances

B

TC of Bridge Resistances +0.28 +0.32 +0.36 %/K

B

A

Peak to peak output swing

A

TC of peak to peak output

B

O

swing

A

CC1

Output offset voltage

A

CC2

B

TC of output offset voltage -4 0 +4 µV/V/K

A

Angular Inaccuracy 0.05 0.2 deg

A

Angular hysteresis

Isolation Bridge Current

TCR

∆V

O1/VCC1

∆V

O2/VCC2

TCV

V

OFF1

V

OFF2

TCV

TCk

R

B1

or

R

B2

or

or

∆α

∆αH

I

iso1-2

/V

/V

OFF

(†)

, k=100•(V

α1=135°, α2=0°

TA = -40 to +160°C

no H

ROT

H

= 8 kA/m

ROT

H

= 8 kA/m

ROT

no H

ROT

H

ROT

no H

PO1/VPO2

TA = -40°C

TA = 23°C

TA = +160°C

TA = -40°C

TA = 23°C

TA = +160°C

(†)

T

TA = -40°C

TA = +160°C

(†)

T

= 8 kA/m

ROT

= 23°C

A

= 23°C

A

(†)

) with V

CC1=VCC2

TYP

(*)

0.35 mV/V/deg

40 50 60 mV

-0.008 +0.008 %/K

2017 3040

2500 3000 3600

3345 5114

19.2 30.4

16 20 24

6.7 13.4

16 20 24

-0.35 -0.32 -0.28 %/K

-1.25 +1.25

-1.55 +1.55

-1 0 +1

-2 0 +2

00.1µA

ZMT32

MAX UNIT

Ω

mV/V

mV/V

0.1 deg

0.5

(‡)

deg

(*) Typical values apply to an ambient temperature of 23oC

(†) See point “Magnetic Field Tests” below

(‡) The accurate control of this parameter (Lim

=0.1deg, H

max

=25kA/m) takes place by means of sample tests

ROT

A: Output characteristic definitions

∆VO1/V

V

OFF1/VCC1

∆αH = MAX | α
∆α = MAX | α

CC1

= (V

= ½(V

o

– V

OMAX1

OMAX1

LEFT TURN

OMIN1

+ V

OMIN1

– α

RIGHT TURN

)/V

or/ ∆VO2/V

CC1

)/V

or/ V

CC1

= (V

CC2

OFF2/VCC2

OMAX2

= ½(V

– V

OMAX2

OMIN2

+ V

)/V

CC2

OMIN2

)/V

| (max. angular difference between left and right turn)

CC2

– α | (max. angular difference between actual value αoand measured angle,

without offset error)

B: Temperature coefficient (TC) equations

T1 = -25°C, T0 = +25°C, T2 = +125°C

where

is the peak-peak output voltage at temperature T

n

Issue 1 - June 2008 3 www.zetex.com

© Zetex Semiconductors plc 2008

ZMT32

%100

)T(R

)T(R)T(R

TT

1

TCR

0B

1B2B

12

B

×

−

×

−

=

)TT(

VV

TCV

12

)1T(OFF)2T(OFF

OFF

−

−

=

⎟

⎟
⎠

⎞

⎜

⎜
⎝

⎛

=α=

1O

2O

V

V

arctan]anglemeasured[

where R

where V

) is the bridge resistance at temperature T

B(Tn

is the output offset voltage at temperature T

OFF(Tn)

n

n

Magnetic field tests

For these tests a rotating magnetic field is generated and the output signals of both bridges are measured at
four different field angles for right rotation as well as for left rotation. Using these measured output signals
the diameter and the center coordinates of the best circle are calculated. They correspond to the output
voltage range and the offset voltage. Furthermore the field angles for both rotation directions and angular
hysteresis are calculated

Method

The data pairs are transformed onto a unit circle starting from their position in the data collection
for determining direction information or angle information.

It must be evaluated with four pair values (cos, sin) on a right rotation (magnetic field rotation)
and four pair values (cos, sin) on a left rotation (magnetic field rotation).

The field rotation steps are:

Æ start in 180° position

§ right rotation to 22.5° with measurement of sensor outputs

§ right rotation to 67.5° with measurement of sensor outputs

§ right rotation to 112.5° with measurement of sensor outputs

§ right rotation to 157.5° with measurement of sensor outputs

§ right rotation to 0° (360°) , stop , reversal

§ left rotation to 157.5° with measurement of sensor outputs

§ left rotation to 112.5° with measurement of sensor outputs

§ left rotation to 67.5° with measurement of sensor outputs

§ left rotation to 22.5° with measurement of sensor outputs , end position

General description of tests with external magnetic field.

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Operating principle

e

e

-V

O1

-V

O2

V

cc1

V

cc2

GND1

GND2

+V

O1

+V

O2

1

-15

-10

-5

0

5

10

0 45 90 135 180 225 270 315 360

Output vol tage (mV /V )

Cos 2

α

Sin 2

α

Sensor bridge 2
Sensor bridge 1

ZMT32

GND1

H

O

rot

0

8

Bridg

1

␣

α = 0°

1

1

-

O1

V

GND2

7

2

-V

O2

+V

6

Bridg

2

3

V

CC2

O2

O1

+V

5

4

V

CC1

When a common-magnetic field is applied through the
ZMT32 the 2 internal magneto-resistive bridges are
affected slightly differently due to their 45° rotation to
one another. This 45° rotation enables the ZMT32 to
determine angular position, of a rotating magnetic
field.

When a rotating magnetic field is applied to the ZMT32
it will output 2 sinusoidal voltages that are:

• proportional to the field strength applied

• proportional to the supply voltage applied,

• rotating at twice the angular position

Characteristic output curves V

O1

, V

O2

Issue 1 - June 2008 5 www.zetex.com

© Zetex Semiconductors plc 2008

• 90° apart (as seen below).

By taking the arcTan of the ratio of V

to VO1 the

O2

angular position of the magnetic field can be
determined.

Typical characteristics

0.0%

0.2%

0.4%

0.6%

0.8%

1.0%

1.2%

1.4%

01020304050

H

ROT

- Field strength (kA/m)

Angle accuracy

0

5

10

15

20

25

01020304050

Accuracy variance with field strength

V

CC1=VCC2

=+5V

T

A

=23oC

k=100

Output variance with magnetic field strength

H

ROT

- Field strength (kA/m)

Output voltage (mV/V)

V

CC1=VCC2

=+5V

T

A

=23oC

k=100

ZMT32

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Typical characteristics

0

5

10

15

20

25

30

35

-50 -25 0 25 50 75 100 125 150 175

MAX

MIN

0

1000

2000

3000

4000

5000

6000

-50 -25 0 25 50 75 100 125 150 175

MAX

MIN

Output voltage versus temperature

Temperature (

o

C)

Output voltage (mV/V)

V

CC1=VCC2

=+5V

T

A

=23oC

k=100

V

CC1=VCC2

=+5V

T

A

=23oC

k=100

Temperature (oC)

Bridge resistance (Ω)

Bridge resistance versus temperature

ZMT32

Issue 1 - June 2008 7 www.zetex.com

© Zetex Semiconductors plc 2008

Typical application

CC

+V

result of angle

measurement

ZMT32

GND

OUT1

V

-

tan

D

A

␮p

D

A

OUT2

V

fixed 45 degree phase

difference between

outputs 1 and 2

-

+

+

R2

41

COS

R1

top view

ZMT32T8

R1

SIN

85

R3

R4

R3

R2

R4

Issue 1 - June 2008 8 www.zetex.com

© Zetex Semiconductors plc 2008

ZMT32

2.8

0.110

6.8

0.268

4.6

0.181

0.95

0.037

1.52

0.060

mm

inches

Package outline - SM-8 Soldering footprint

DIM Millimeters Inches DIM Millimeters Inches

Min. Max. Typ. Min. Max. Typ. Min. Max. Typ. Min. Max. Typ.

A - 1.7 - - 0.067 - e1 - - 4.59 - - 0.1807

A1 0.02 0.1 - 0.0008 0.004 - e2 - - 1.53 - - 0.0602

b - - 0.7 - - 0.0275 He 6.7 7.3 - 0.264 0.287 -

c 0.24 0.32 - 0.009 0.013 - Lp 0.9 - - 0.035 - -

D 6.3 6.7 - 0.248 0.264 - ␣ - 15° - - 15° -

E 3.3 3.7 - 0.130 0.145 - ␤ - - 10° - - 10°

Note: Controlling dimensions are in millimeters. Approximate dimensions are provided in inches

Issue 1 - June 2008 9 www.zetex.com

© Zetex Semiconductors plc 2008

ZMT32

Definitions
Product change

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service. Customers are solely responsible for obtaining the latest relevant information before placing orders.

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The circuits in this design/application note are offered as design ideas. It is the responsibility of the user to ensure that the circuit is fit for
the user’s application and meets with the user’s requirements. No representation or warranty is given and no liability whatsoever is
assumed by Zetex with respect to the accuracy or use of such information, or infringement of patents or other intellectual property rights
arising from such use or otherwise. Zetex does not assume any legal responsibility or will not be held legally liable (whether in contract,
tort (including negligence), breach of statutory duty, restriction or otherwise) for any damages, loss of profit, business, contract,
opportunity or consequential loss in the use of these circuit applications, under any circumstances.

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Zetex products are specifically not authorized for use as critical components in life support devices or systems without the express written
approval of the Chief Executive Officer of Zetex Semiconductors plc. As used herein:
A. Life support devices or systems are devices or systems which:

1. are intended to implant into the body

or

2. support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the
labelling can be reasonably expected to result in significant injury to the user.

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cause the failure of the life support device or to affect its safety or effectiveness.

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Semiconductor devices are susceptible to damage by ESD. Suitable precautions should be taken when handling and transporting devices.
The possible damage to devices depends on the circumstances of the handling and transporting, and the nature of the device. The extent
of damage can vary from immediate functional or parametric malfunction to degradation of function or performance in use over time.
Devices suspected of being affected should be replaced.

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Zetex Semiconductors is committed to environmental excellence in all aspects of its operations which includes meeting or exceeding
regulatory requirements with respect to the use of hazardous substances. Numerous successful programs have been implemented to
reduce the use of hazardous substances and/or emissions.
All Zetex components are compliant with the RoHS directive, and through this it is supporting its customers in their compliance with
WEEE and ELV directives.

Product status key:

“Preview” Future device intended for production at some point. Samples may be available
“Active” Product status recommended for new designs
“Last time buy (LTB)” Device will be discontinued and last time buy period and delivery is in effect
“Not recommended for new designs”
“Obsolete” Production has been discontinued

Datasheet status key:

“Draft version” This term denotes a very early datasheet version and contains highly provisional information, which

“Provisional version” This term denotes a pre-release datasheet. It provides a clear indication of anticipated performance.

“Issue” This term denotes an issued datasheet containing finalized specifications. However, changes to

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Telefon: [phone]
Fax: [phone]
[e-mail]

© 2008 Published by Zetex Semiconductors plc

Device is still in production to support existing designs and production

may change in any manner without notice.

However, changes to the test conditions and specifications may occur, at any time and without notice.

specifications may occur, at any time and without notice.

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