MCT8316Z datasheet(49/100 Pages) TI

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8.3.13 Hall Comparators (Analog Hall Inputs)

Three comparators are provided to process the raw signals from the Hall-effect sensors to commutate the motor.

The Hall comparators sense the zero crossings of the differential inputs and pass the information to digital logic.

The Hall comparators have hysteresis, and their detect threshold is centered at 0. The hysteresis is defined as

shown in Figure 8-39.

In addition to the hysteresis, the Hall inputs are deglitched with a circuit that ignores any extra Hall transitions

for a period of tHDEG after sensing a valid transition. Ignoring these transitions for the tHDEG time prevents PWM

noise from being coupled into the Hall inputs, which can result in erroneous commutation.

If excessive noise is still coupled into the Hall comparator inputs, adding capacitors between the positive and

negative inputs of the Hall comparators may be required. The ESD protection circuitry on the Hall inputs

implements a diode to the AVDD pin. Because of this diode, the voltage on the Hall inputs should not exceed the

AVDD voltage.

Because the AVDD pin is disabled in sleep mode (nSLEEP inactive), the Hall inputs should not be driven by

external voltages in sleep mode. If the Hall sensors are powered externally, the supply to the Hall sensors should

be disabled if the MCT8316Z-Q1 device is put into sleep mode. In addition, the Hall sensors' power supply

should be powered up after enabling the motor otherwise an invalid Hall state may cause a delay in motor

operation.

VHYS/2

Hall Differential

Voltage (VID/2)

Hall Comparator

Output

tHDEG (Hall

Deglitch Time)

Hall Comparator

Common Mode

Voltage (VCM)

Time

Figure 8-39. Hall Comparators Operation

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MCT8316Z-Q1

SLVSGO3 – DECEMBER 2021

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