AS5045

Data Sheet

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Revision 1.7

18 – 33

11 Programming the AS5045

After power-on, programming the AS5045 is enabled with the rising edge of CSn and Prog = logic high. 16 bit

configuration data must be serially shifted into the OTP register via the Prog pin. The first “CCW” bit is followed by

the zero position data (MSB first) and the Mode setting bits. Data must be valid at the rising edge of CLK (see

Figure 10

).

After writing the data into the OTP register it can be permanently programmed by rising the Prog pin to the

programming mode, the chip must be reset by a power-on-reset. The programmed data is available after the next

power-up.

Note: During the programming process, the transitions in the programming current may cause high voltage spikes

generated by the inductance of the connection cable. To avoid these spikes and possible damage to the IC, the

connection wires, especially the signals Prog and VSS must be kept as short as possible. The maximum wire length

voltage spikes, a 10nF ceramic capacitor should be connected close to pins VPROG and VSS. This capacitor is only

rate to ensure that the signal Prog is stable at the rising edge of CLK (see Figure 10). Additionally, the programming

supply voltage should be buffered with a 10µF capacitor mounted close to the switching transistor. This capacitor

aids in providing peak currents during programming. The specified programming voltage at pin Prog is 7.3 ~ 7.5V

(see section 6.8).

set slightly higher (7.5 ~ 8.0V, see Figure 12).

OTP Register Contents:

CCW

Counter Clockwise Bit

ccw=0 – angular value increases in clockwise direction

ccw=1 – angular value increases in counter clockwise direction

Z [11:0]:

Programmable Zero Position

PWM dis:

Disable PWM output

MagCompEn:

When set, activates LIN alarm both when magnetic field is too high and too low (see Table 5)

PWMhalfEn:

When set, PWM frequency is 122Hz or 2µs / step (when PWMhalfEN = 0, PWM frequency is 244Hz,

1µs / step)

11.1 Zero Position Programming

Zero position programming is an OTP option that simplifies assembly of a system, as the magnet does not need to

be manually adjusted to the mechanical zero position. Once the assembly is completed, the mechanical and

electrical zero positions can be matched by software. Any position within a full turn can be defined as the permanent

new zero position.

For zero position programming, the magnet is turned to the mechanical zero position (e.g. the “off”-position of a

rotary switch) and the actual angular value is read.

This value is written into the OTP register bits Z11:Z0 (see Figure 10) and programmed (see Figure 11).

Note:

The zero position value may also be modified before programming, e.g. to program an electrical zero position

that is 180° (half turn) from the mechanical zero position, just add 2048 to the value read at the mechanical zero

position and program the new value into the OTP register.

11.2 Repeated OTP Programming

Although a single AS5045 OTP register bit can be programmed only once (from 0 to 1), it is possible to program

other, unprogrammed bits in subsequent programming cycles. However, a bit that has already been programmed

should not be programmed twice. Therefore it is recommended that bits that are already programmed are set to “0”

during a programming cycle.