AS5046 Programmable 360° Magnetic Angle Encoder – Preliminary Data Sheet

Revision 1.1

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Page 15 of 33

9.6

AGC and Magnitude Registers

The AS5046 allows the readout of two additional registers related to magnetic field strength: magnitude and AGC registers.

Figure 9 shows a graphic example of the interrelations of these two registers in respect to the magnetic field strength of the

magnet (all register levels are in decimal format).

at a low magnetic field strength (below level B1 / B2) the magnitude will be <32 and the AGC will be at maximum: 255. the

LIN status bit will be set (red range). It is not recommended to operate in this range, although the AS5046 will still produce

usable results at very weak magnetic fields.

if the magnetic field strength is further increased above a magnitude value of 32, LIN will be cleared. The AGC will remain at

255 until the magnitude has reached a value of 63 (yellow range; level B3/B4). The angular data can still be used in the

yellow range, but the noise (=jitter) will be larger than normal.

Once the magnitude is strong enough to reach a value of 63, the AGC will regulate the internal loop gain to maintain this

value. Magnitude will remain at 63 and the AGC will regulate between 0 and 255 (green range; magnetic field strength

between level B3/B4 and B5/B6). This is the recommended operating range

If the magnetic field strength rises further than B5/B4, the AGC can no longer regulate the loop and will be at its minimum

value of 0. The magnitude value will increase (yellow range; up to B7/B8). In this range, the angular data will still be valid.

Due to the rather strong field, there is no issue with noise, but the magnetic field may be more distorted than in the normal

operating range which may lead to additional errors.

Above level B7/B8 the LIN alarm will be set once the magnitude has exceeded a level of 95 (red range). It is not

recommended to operate in this range. The main contributing part for errors will be a more distorted magnetic field.

If the magnitude exceeds a value of 127, the COF (cordic overflow) alarm will be set. This case can only occur with very

strong magnets and does usually not occur in practice. The angular data will be invalid when the COF bit is set.

Figure 9: Magnitude and AGC values vs. magnetic field strength