SBOS531E August 2010 – June 2019 AFE031
The AFE031 contains a two-wire transmitter block, ETx, and a two-wire receiver block, ERx. These blocks support communications that use amplitude shift keying (ASK) with on-off keying (OOK) modulation.
The ETx block is a gated driver that allows for transmission of a carrier input signal and modulating input signal. For typical applications, a 50-kHz square wave carrier signal is applied to E_Tx_Clk while the modulating signal is applied to E_Tx_In. The output (E_Tx_Out) is then in a high-impedance state when E_Tx_In is '1'. Figure 41 shows the relationship between E_Tx_Clk, E_Tx_In, and E_Tx_Out.
The ERx Block consists of a low-pass analog filter configured in an inverting gain of –4.5 db. This block, along with an external capacitor, can be used to create a passband filter response as shown in Figure 42.
The E_Rx_Out pin can be directly connected to either an available analog-to-digital converter (ADC) input or GPIO on the host microcontroller. Figure 43 illustrates a typical two-wire application for ETx and ERx.