AS5045 12-BIT PROGRAMMABLE MAGNETIC ROTARY ENCODER

Revision 1.5

www.austriamicrosystems.com

Page 9 of 24

5

Mode Input Pin

The mode input pin activates or deactivates an internal filter that is used to reduce the analog output noise.

Activating the filter (Mode pin = LOW) provides a reduced output noise of 0.03° rms. At the same time, the output delay is

increased to 384µs. This mode is recommended for high precision, low speed applications.

Deactivating the filter (Mode pin = HIGH) reduces the output delay to 96µs and provides an output noise of 0.06° rms. This

mode is recommended for higher speed applications.

The MODE pin should be set at power-up. A change of the mode during operation is not allowed.

Switching the Mode pin affects the following parameters:

Parameter

slow mode (Mode = low)

fast mode (Mode = high, VDD5V)

sampling rate

2.61 kHz (384 µs)

10.42 kHz (96µs)

transition noise (1 sigma)

≤ 0.03° rms

≤ 0.06° rms

output delay

384µs

96µs

max. speed @ 4096 samples/rev.

max. speed @ 1024 samples/rev.

max. speed @ 256 samples/rev.

max. speed @ 64 samples/rev.

38 rpm

153 rpm

610 rpm

2441 rpm

153 rpm

610 rpm

2441 rpm

9766 rpm

Table 2: Slow and fast mode parameters 12-bit Absolute Angular Position Output

5.1

Synchronous Serial Interface (SSI)

D11

1

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

OCF

COF

LIN

Mag

INC

Mag

DEC

Even

PAR

D11

1

18

8

t

CLK FE

t

CSn

t

DO Tristate

Status Bits

Angular Position Data

t

DO valid

t

DO active

T

CLK/2

t

CLK FE

CSn

DO

CLK

Figure 5: Synchronous serial interface with absolute angular position data

If CSn changes to logic low, Data Out (DO) will change from

high impedance (tri-state) to logic high and the read-out will

be initiated.

output shift register with the first falling edge of CLK.

Each subsequent rising CLK edge shifts out one bit of

data.

The serial word contains 18 bits, the first 12 bits are

the angular information D[11:0], the subsequent 6 bits

contain system information, about the validity of data

such as OCF, COF, LIN, Parity and Magnetic Field

status (increase/decrease).

A subsequent measurement is initiated by a “high”

5.1.1

Data Content

D11:D0 absolute angular position data (MSB is clocked

out first)

OCF (Offset Compensation Finished), logic high

indicates the finished Offset Compensation Algorithm

COF (Cordic Overflow), logic high indicates an out of

range error in the CORDIC part. When this bit is set, the

data at D9:D0 is invalid. The absolute output maintains

the last valid angular value.

This alarm may be resolved by bringing the magnet

within the X-Y-Z tolerance limits.

LIN (Linearity Alarm), logic high indicates that the input

field

generates

a

critical

output

linearity.

When this bit is set, the data at D9:D0 may still be used,

but can contain invalid data. This warning may be

resolved by bringing the magnet within the X-Y-Z

tolerance limits.

Even Parity bit for transmission error detection of bits

1…17 (D11…D0, OCF, COF, LIN, MagINC, MagDEC)