AS8579 datasheet(14/44 Pages) OSRAM

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AS8579

Functional Description

Datasheet

• PUBLIC

DS000707

• v4-01 • 2022-Jun-08

│ 13

Functional Description

The transceiver Analog Front-End (AFE) architecture performs the primary function of the AS8579,

which is to sense the impedance of the output load. This is done using transmitter and receiver blocks.

The transmitter block supplies the load a sine wave across. Then the receiver block captures the

current response of the load. Here the change of the current in phase and modulus will be sensed.

The current response is converted to a voltage via trance-impedance amplifier and then demodulated

into in-phase (I) and quadrature (Q) components. I and Q components are then filtered and converted

to 10-bit digital words via ADC. These I and Q words are accumulated awaiting 16-bit SPI

transmission.

Current response can be measured on any of the 10 SEN pins connected to the Sensor Driver

through analog multiplexers (MUX). The external processor controls the MUX. The processor retrieves

the I and Q components of each sensor from AS8579 and then determines the size of the impedance

load of the external sensor(s).

There are four selectable non-harmonic sensor frequencies for generating the sensor driver output

signal: 45.45 kHz, 71.43 kHz, 100 kHz and 125 kHz. This can be set in FREQ register (see 7.2.7)

AS8579 Datasheet(PDF) 14 Page - OSRAM GmbH