MAQ430 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & UVW OUTPUTS

MAQ430 Rev. 1.2

www.MonolithicPower.com

19

8/8/2022

MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.

© 2022 MPS. All Rights Reserved.

REGISTER SETTINGS

Zero Setting

The zero position of the MagAlpha (a0) can be

programmed with 16 bits of resolution. The

angle streamed out by the MagAlpha (aout) is

given by Equation (2):

0

a

a

a

raw

out





(2)

Where araw is the raw angle provided by the

MagAlpha front end.

The parameter Z(15:0), which is zero by

default, is the complementary angle of the zero

setting. In decimals, it can be written as shown

in Equation (3):

)

0

:

15

(

2

16

0

Z

a





(3)

Table 8 shows the zero setting parameter.

Table 8: Zero Setting Parameter

Z(15:0)

Zero pos.

a0 (16-bit dec)

Zero pos.

a0 (deg)

0

65536

360.000

1

65535

359.995

2

65534

359.989

…

…

…

65534

2

0.011

65535

1

0.005

Example

To set the zero position to 20 degrees, the

Z(15:0)

parameter

shall

be

equal

to the

complementary angle and can be calculated

with Equation (4):

61895

2

deg

360

deg

20

2

)

0

:

15

(

16

16







Z

(4)

In binary, it is written as 1111 0001 1100 0111.

Table 9 shows the content of registers 0 and 1.

Table 9: Register Content

Reg Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

0

1

1

0

0

0

1

1

1

1

1

1

1

1

0

0

0

1

Rotation Direction

By default, when looking at the top of the

package,

the

angle

increases

when

the

magnetic field rotates clockwise (CW) (see

Figure 15 and Table 10).

Figure 15: Positive Rotation Direction of the

Magnetic Field

Table 10: Rotation Direction Parameter

RD

Positive Direction

0

Clockwise (CW)

1

Counterclockwise (CCW)

BCT Settings (Bias Current Trimming)

Side-Shaft

When the MAQ430 is mounted on the side of

the magnet, the relation between the field angle

and the mechanical angle is no longer directly

linear. This effect is related to the fact that the

tangential magnetic field is usually smaller than

the radial field. Define the field ratio k with

Equation (5):

tan

/ B

B

k

rad



(5)

Where Brad is the maximum radial magnetic

field, and Btan is the maximum tangential

magnetic field (see Figure 16).

Figure 16: Side-Shaft Field

The ratio k depends on the magnet geometry

and distance to the sensor. Having a k ratio

different than 1 results in the sensor output

response not being linear with respect to the

mechanical angle. Note that the error curve has

the shape of a double sinewave (see Figure

18). E is the amplitude of this error.