AD7617BSTZ datasheet(27/52 Pages) AD

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AD7617

Data Sheet

Rev. 0 | Page 26 of 51

APPLICATIONS INFORMATION

FUNCTIONALITY OVERVIEW

The AD7617 has two main modes of operation: hardware mode

and software mode. Additionally, the communications interface

for hardware or software mode can be serial or parallel. Depending

on the mode of operation and interface chosen, certain functional-

ity may not be available. Full functionality is available in both

software serial and software parallel mode with restricted

functionality in hardware serial mode and hardware parallel mode.

Table 11 shows the functionality available in the different modes of

operation.

POWER SUPPLIES

The AD7617 has two independent power supplies, VCC and VDRIVE,

that supply the analog circuitry and digital interface, respectively.

Decouple both the VCC supply and the VDRIVE supply with a 10 µF

capacitor in parallel with a 100 nF capacitor.

Additionally, these supplies are regulated by two internal LDO

regulators. The analog LDO (ALDO) typically supplies 1.87 V.

Decouple the ALDO with a 10 µF capacitor between the

REGCAP and REGGND pins. The digital LDO (DLDO)

typically supplies 1.89 V. Decouple the DLDO with a 10 µF

capacitor between the REGCAPD and REGGNDD pins.

The AD7617 is robust to power supply sequencing. The recom-

mended sequence is to power up VDRIVE first, followed by VCC.

Hold RESET low until both supplies are stabilized.

TYPICAL CONNECTIONS

Figure 50 shows the typical connections required for correct

operation of the AD7617. Decouple the VCC and VDRIVE supplies

as shown in Figure 50. Place the smaller, 0.1 µF capacitor as close to

the supply pin as possible, with the larger 10 µF bulk capacitor in

parallel. Decouple the reference and LDO regulators as shown

in Figure 50 and as described in Table 7.

The analog input pins require a matched resistance, R, on both

the VxA and VxAGND (similarly, VxB and VxBGND) inputs

to avoid a gain error on the analog input channels caused by an

impedance mismatch.

Table 11. Functionality Matrix

Functionality

Operation Mode1

Software Mode, HW_RNGSELx = 00

Hardware Mode, HW_RNGSELx ≠ 00

Serial, SER/PAR = 1

Parallel, SER/PAR = 0

Serial, SER/PAR = 1

Parallel, SER/PAR = 0

Internal/External Reference

Yes

Selectable Analog Input Ranges

Individual Channel Configuration

Yes

Common Channel Configuration

Yes

Sequential Sequencer

Yes

Fully Configurable Sequencer

Yes

Burst Mode

Yes

On-Chip Oversampling

Yes

CRC

Yes

Diagnostic Channel Conversion

Yes

Hardware Reset

Yes

Serial 1-Wire Mode

Yes

Serial 2-Wire Mode

Yes

Yes means available; no means not available.

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