AF6ZP0CA – COMBIAC0 & ACE0 2uC – User Manual Page – 25/155
U If an analog input is used as a speed feedback, a system safety strategy
must be defined.
U The application software takes care of analog input errors such as VACC
OUT OF RANGE or VACC NOT OK. See paragraph 10.3.
4.4.4 Special inputs
Special inputs normally configured as digital inputs active to -B are available on
pins A18 and A21. It is possible to configure them differently in order to get two
additional digital inputs active to +B or two additional analog inputs (electrically
compatible with standard digital or analog inputs).
A proper hardware configuration permits to transform A18 and A21 in an interface
for a sense-coil or for an absolute sin/cos sensor (PMSM) for special applications
that use brushless motor. For more details about sensor installation see also
paragraphs 5.2.5, 5.2.6.
Protection
Each special input has a 22 nF capacitor to -B for ESD protection.
Connector position
A18, A21.
4.4.5 Encoder inputs
Inputs for motor-speed feedback (encoder signals) have an internal 1 k pull-up
for open-collector sensor output. Threshold levels are listed below.
Supply voltage 5 V 12 V
Logic low
1.4 V 6.4 V
Logic high
3.5 V 4.3 V
Speed-sensor signals are acquired through the quadrature peripheral of the
microcontroller.
Protection
Encoder inputs are protected against short circuits to +B and -B and have ESD
suppressor to -B for ESD protection.
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