9.1.3 Included Functions and Filter Selection

As a highly integrated device, the DAC874xH not only includes the modulation and demodulation capabilities for the previously described industrial protocols, but also includes an internal reference, and integrated receive bandpass filter, with other aforementioned functions. In HART mode, an internal amplifier provides high output drive capability, and can drive a wide range of purely capacitive loads, ranging from 5 nF to 22 nF. Load conditions within this range maintain output stability. Two different filter configurations, external and internal, are achievable through the BPF_EN digital input -- logic high on this pin enables the internal bandpass filter. The external filter configuration is shown in Figure 32. The example provided displays the DAC874XH device configured with an external reference and external bandpass filter.

Figure 32. HART Mode: DAC874XH Passive Selection For External Bandpass Filter and External Reference

The second configuration, which can reduce costs associated with PCB development and BOM component counts, additionally aids in the optimization of board space. This optimization gives the user flexibility into achieving industrial applications with smaller form factor sizes. The internal filter configuration, with correct MOD_IN, MOD_INF, and MOD_OUT connections, is shown in Figure 33.

Figure 33. HART Mode: DAC874xH Passive Selection For Internal Filter