Cirrus Logic CS5368 - Manual (Page 19)

DS624F5 19
CS5368
4. APPLICATIONS
4.1 Power
CS5368 features five independent power pins that power various functional blocks within the device and
allow for convenient interfacing to other devices.
Table 1 shows what portion of the device is powered from
each supply pin. Please refer to “Recommended Operating Conditions” on page 10 for the valid range of
each power supply pin. The power supplied to each power pin can be independent of the power supplied to
any other pin.
To meet full performance specifications, the CS5368 requires normal low-noise board layout. The “Typical
Connection Diagram” on page 9 shows the recommended power arrangements, with the VA pins connected
to a clean supply. VD, which powers the digital filter, may be run from the system logic supply, or it may be
powered from the analog supply via a single-pole decoupling filter.
Decoupling capacitors should be placed as near to the ADC as possible, with the lower value high-frequen-
cy capacitors placed nearest to the device leads. Clocks should be kept away from the FILT+ and VQ pins
in order to avoid unwanted coupling of these signals into the device. The FILT+ and VQ decoupling capac-
itors must be positioned to minimize the electrical path to ground.
The CDB5368 evaluation board demonstrates optimum layout for the device.
4.2 Control Port Mode and Stand-Alone Operation
4.2.1 Stand-Alone Mode
In Stand-Alone Mode, the CS5368 is programmed exclusively with multi-use configuration pins. This mode
provides a set of commonly used features, which comprise a subset of the complete set of device features
offered in Control Port Mode.
To use the CS5368 in Stand-Alone Mode, the configuration pins must be held in a stable state, at valid logic
levels, and RST must be asserted until the power supplies and clocks are stable and valid. More informa-
tion on the reset function is available in
Section 4.5 on page 22 .
4.2.2 Control Port Mode
In Control Port Mode, all features of the CS5368 are available. Four multi-use configuration pins become
software pins that support the I²C or SPI bus protocol. To initiate Control Port Mode, a controller that sup-
ports I²C or SPI must be used to enable the internal register functionality. This is done by setting the CP-
EN bit (Bit 7 of the Global Control Port Register). Once CP-EN is set, all of the device configuration pins
are ignored, and the internal register settings determine the operating modes of the part.
Figure 4.13 on
page 30 provides detailed information about the I²C and SPI bus protocols.
Power Supply Pin
Pin Name Pin Number Functional Block
VA 4, 9 Analog Core
VX 20 Crystal Oscillator
VD 33 Digital Core
VLS 28 Serial Audio Interface
VLC 35 Control Logic
Table 1. Power Supply Pin Definitions