Datasheet

0
20
40
-
-
Gain (dB)
10 100
1k 10k 100k 1M 10M 100M
Frequency (Hz)
High-pass cutoff determined by:
f =
HP
1
2 R Cp
· ·
IN EXT
where:
R = Input resistance of ERx = 78 k
C = External capacitance
W
IN
EXT
Time (s)
E_Tx_Out
E_Tx_In
E_Tx_Clk
3.3
3.3
3.3
0
0
0
AFE031
www.ti.com SBOS531D –AUGUST 2010–REVISED MAY 2012
ETx and ERx Blocks
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 42
shows the relationship between E_Tx_Clk, E_Tx_In, and E_Tx_Out.
Figure 42. ETx Block Transfer Function
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 43.
Figure 43. ERx Block Frequency Response
Copyright © 2010–2012, Texas Instruments Incorporated 33
Product Folder Link(s): AFE031