STWBC2-HP datasheet(16/96 Pages) STMICROELECTRONICS

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Parameter

Value

Demodulation LPF

3rd order

F1 adjustable by SPI registers to 4k-Hz, 8k-Hz, 12k-Hz, 16k-Hz

Frequency tolerance +/-10%

Comparator hysteresis

Adjustable by SPI registers

0.6 mV,

1.2 mV,

2.4 mV

2.1.5.2

Current demodulator

The current demodulator detects Rx modulation from the variation of the bridge current.

Figure 21. Current demodulator

The bridge current monitor provides a voltage image Bridge_I. As the current is sensed on the bridge supply,

it is naturally rectified by the toggling of the driver. Hence, the image of the current can be directly filtered to

retrieve the modulation. This signal is filtered using a HPF and an LPF to select the band of the useful modulation.

This filtered signal is shipped to ADC mux for STM32 acquisition through ADC. The signal is also pushed to a

comparator in order to ship a direct digital 1bit form of the modulation to an STM32 GPIO. A configurable gain

allows adapting the signal level to the filtering chain.

Table 11. Current demodulator operating parameters

Topic

Value

Demodulation HPF

2nd order

F0 adjustable by SPI registers to 300 Hz, 450 Hz, 600 Hz, 750 Hz

Frequency tolerance +/-10%

Demodulation LPF

3rd order

F1 adjustable by SPI registers to 4k Hz, 8k Hz, 12k Hz, 16k Hz

Frequency tolerance +/-10%

Comparator hysteresis

Adjustable by SPI registers

0.6 mV,

1.2 mV,

2.4 mV

STWBC2-HP

Analog AFE functions

DS13825 - Rev 1.0

page 16/96

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