AS5040 − Programming the AS5040
Programming the AS5040
After power-on, programming the AS5040 is enabled with the
rising edge of CSn with Prog = high and CLK = low. 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 incremental mode setting as
shown in Table 6. Data must be valid at the rising edge of CLK
(see Figure 33).
After writing data into the OTP register it can be permanently
programmed by rising the Prog pin to the programming voltage
VPROG. 16 CLK pulses (tPROG) must be applied to program the
fuses (Figure 34). To exit the programming mode, the chip must
be reset by a power-on-reset. The programmed data is available
after the next power-up.
Note(s): 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 between the VPROG
switching transistor and pin Prog (see Figure 35) should not
exceed 50mm (2 inches). To suppress eventual voltage spikes,
a 10nF ceramic capacitor should be connected close to pins
Prog and VSS. This capacitor is only required for programming,
it is not required for normal operation.
The clock timing tclk must be selected at a proper rate to ensure
that the signal Prog is stable at the rising edge of CLK (see
Figure 33). 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 0). To compensate for the voltage drop across the VPROG
switching transistor, the applied programming voltage may be
set slightly higher (7.5 - 8.0V, see Figure 35).
OTP Register Contents:
CCW
Counter Clockwise Bit
• ccw=0 – angular value increases in clockwise
direction
• ccw=1 – angular value increases in
counterclockwise direction
Z [9:0]
Programmable Zero / Index Position
Indx
Index Pulse Width Selection: 1LSB / 3LSB
Div1, Div0 Divider Setting of Incremental Output
Md1, Md0 Incremental Output Mode Selection
ams Datasheet
[v2-12] 2017-Jun-20
Page 29
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