User Manual

AND8399/D
http://onsemi.com
14
Figure 16. SLA Voltage at Maximum Speed in Not Transparent Mode
Notice in Figure 16 that the measured SLA
voltage is about 2.5 V. If the measured voltage
would be clamped to 5 V it’s possible that the
generated BEMF is too high. Set the SLA Gain
to 1/4 (Control Register 2).
When the NXT frequency is increased to 7 kHz
(875 FS/sec), the BEMF is sometimes sampled
too fast resulting in an incorrect SLA voltage
(see Figure 17). The jumps in the SLA voltage
is because the coil current zero crossing is left
too early and the transient part is sampled (see
also Figure 11).