MA302 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS

MA302 Rev. 1.1

www.MonolithicPower.com

11

2/7/2020

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Figure 4: End-of-Shaft Mounting

If the end-of-shaft position is not available, the

sensor can be positioned away from the rotation

axis of a cylinder or ring magnet (see Figure 5).

In this case, the magnetic field angle is no longer

directly proportional to the mechanical angle.

The MA302 can be adjusted to compensate for

this effect and recover the linear relation

between the mechanical angle and the sensor

output. With multiple pole pair magnets, the

MA302 indicates multiple rotations for each

mechanical turn.

Figure 5: Side-Shaft Mounting

Electrical Mounting and Power Supply

Decoupling

It is recommended to place a 1µF decoupling

capacitor close to the sensor with a low

impedance path to GND (see Figure 6).

Figure 6: Connection for Supply Decoupling

Generally, the MagAlpha works fine with or

without the exposed pad connected to anything.

For optimum conditions (electrically, thermally,

and mechanically), it is recommended that the

exposed pad be connected to ground.

Serial Interface

The sensor supports the SPI serial interface for

angle reading and register programming.

SPI

SPI

is

a

4-wire,

synchronous,

serial

communication

interface.

The

MagAlpha

supports SPI Mode 3 and Mode 0 (see Table 1

and Table 2). The SPI Mode (0 or 3) is detected

automatically by the sensor and therefore does

not require any action from the user. The

maximum clock rate supported on SPI is 25MHz.

There is no minimum clock rate. Note that real

life data rates depend on PCB layout quality and

signal trace length. See Figure 7, Figure 8, and

Table 3 for SPI timing.

All commands to the MagAlpha (whether for

writing or reading register content) must be

transferred through the SPI MOSI pin and must

be 16 bits long. See the SPI Communication

section on page 13 for details.

Table 1: SPI Specification

Mode 0

Mode 3

SCLK idle state

Low

High

Data capture

On SCLK rising edge

Data transmission

On SCLK falling edge

CS idle state

High

Data order

MSB first

Table 2: SPI Standard

Mode 0

Mode 3

CPOL

0

1

CPHA

0

1

Data order (DORD)

0 (MSB first)