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DS861PP1

CS5346

5.9

Reset

When RST is low, the CS5346 enters a low-power mode and all internal states are reset, including the con-

trol port and registers, the outputs are muted. When RST is high, the control port becomes operational, and

the desired settings should be loaded into the control registers. Writing a 0 to the PDN bit in the Power Con-

trol register will then cause the part to leave the low-power state and begin operation.

The delta-sigma modulators settle in a matter of microseconds after the analog section is powered, either

through the application of power or by setting the RST pin high. However, the voltage reference will take

much longer to reach a final value due to the presence of external capacitance on the FILT+ pin. During this

voltage reference ramp delay, SDOUT will be automatically muted.

It is recommended that RST be activated if the analog or digital supplies drop below the recommended op-

erating condition to prevent power-glitch-related issues.

5.10

Synchronization of Multiple Devices

In systems where multiple ADCs are required, care must be taken to achieve simultaneous sampling. To

ensure synchronous sampling, the master clocks and left/right clocks must be the same for all of the

CS5346s in the system. If only one master clock source is needed, one solution is to place one CS5346 in

Master Mode, and slave all of the other CS5346s to the one master. If multiple master clock sources are

needed, a possible solution would be to supply all clocks from the same external source and time the

CS5346 reset with the inactive edge of master clock. This will ensure that all converters begin sampling on

the same clock edge.

5.11

Grounding and Power Supply Decoupling

As with any high-resolution converter, the CS5346 requires careful attention to power supply and grounding

arrangements if its potential performance is to be realized. Figure 7 shows the recommended power ar-

rangements, with VA connected to a clean supply. VD, which powers the digital filter, may be run from the

system logic supplies (VLS or VLC). Power supply decoupling capacitors should be as near to the CS5346

as possible, with the low value ceramic capacitor being the nearest. All signals, especially clocks, should be

kept away from the FILT+ and VQ pins in order to avoid unwanted coupling into the modulators. The FILT+

and VQ decoupling capacitors, particularly the 0.1 µF, must be positioned to minimize the electrical path

from FILT+ and AGND. The CS5346 evaluation board demonstrates the optimum layout and power supply

arrangements. To minimize digital noise, connect the CS5346 digital outputs only to CMOS inputs.