ST-PLC-AFE datasheet(9/58 Pages) STMICROELECTRONICS

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ST-PLC-AFE

General description

2.1

PA block

The PA block has a low-pass filter response when configured with a gain of 6.9 V/V. The PA

is specified to operate from 7 V to 14 V and can deliver up to 1.65 A of continuous output

current over the specified junction temperature range of -40 °C to 125 °C.

In differential mode, both PAs are turned on (see Figure 3).

In single-ended configuration, the N side of the PA is turned off and its output is placed into

high impedance. This is achieved by setting the PA2_EN bit in the Enable register to 0 (see

Figure 3).

Figure 3. PA equivalent circuit

2.1.1

Typical connections to the PA

Connecting the PA in a typical PLC application requires an input AC coupling capacitor,

C_IN_PA (see Figure 5 and Figure 7). This capacitor introduces a single-pole, high-pass

characteristic to the PA transfer function; combined with the inherent low-pass transfer

function, this characteristic results in a pass band response.

Figure 4 shows the impact of this coupling capacitor.

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