AD74115H datasheet(32/113 Pages) AD

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Data Sheet

AD74115H

THEORY OF OPERATION

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Figure 32. Detailed Functional Block Diagram

The AD74115H is a single-channel, software configurable input

and output that is designed to meet the requirements of isolated

process control and factory automation applications. The device

provides a fully integrated single chip solution for input and output

operation. The AD74115H features a 16-bit, Σ-Δ ADC and a 14-bit

DAC, and the device is packaged in a 7 mm × 7 mm, 48-lead

LFCSP. The AD74115H also includes an integrated HART modem.

The channel is configured by writing to the configuration registers.

Users can refine the default configurations of each operation mode

via the AD74115H register map. See Figure 32 for a detailed

functional block diagram of the AD74115H.

ROBUST ARCHITECTURE

The AD74115H system is robust in noisy environments and can

withstand overvoltage scenarios such as miswire and surge events.

On-chip line protectors ensure that the I/OP screw terminal does

not provide power to the IC when brought to a higher potential than

the AVDD pin.

The recommended external components shown in Figure 32 and

Table 36, including the TVS, are selected to withstand surges on

the input and output terminals.

With the recommended components, the I/OP and I/ON screw

terminals tolerate overvoltages up to dc ± 36 V (limited by the

external TVS).

A cyclic redundancy check (CRC) function is built into the SPI to

ensure error free communications in noisy environments.

POWER SUPPLIES AND REFERENCE

Four external voltage supply rails are required to power up the

AD74115H: VAVDD, which is the positive analog supply, VAVSS,

which is the negative analog supply, VAVCC, which is the low voltage

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