Cirrus Logic AN259 - Manual

1
Copyright © Cirrus Logic, Inc. 2009
(All Rights Reserved)
http://www.cirrus.com
AN259
Transitioning from the CS4382 to the CS4382A or CS4385
1. Introduction
This application note describes how to transition easily to the CS4385 or CS4382A from an existing
design which uses the CS4382. The CS4382A was designed to give a simple upgrade path from the
CS4382 whereas the CS4385 adds some additional features. Please refer to the CS4382A and CS4385
data sheets for supplemental information and specifications concerning operation of the device. A brief
comparison between the product families is shown in Table 1.
1.1 What the CS4382A offers over the CS4382:
• Sixth order multi-bit delta-sigma modulator for lower out of band noise
• Increased full-scale output level for ease of board level noise management
• Improved lower latency PCM digital filter
• Non-decimating DSD processor with on chip 50 kHz filtering
• Uses identical register mapping
1.2 Changes from the CS4382 that the CS4382A requires:
• The VD supply must be changed to 2.5 V from either the 3.3 V or 5 V of the CS4382
• Depending on the desired output voltage requirements, attenuation may need to be added to the off-chip filter.
• Loss of simultaneous support for two synchronous sample rates mode which was available in the CS4382.
This mode provided for dual sample rates such as
192 kHz front channels with 96 kHz surrounds for
DVD audio and required the use of LRCK2 and SCLK2 . This mode is not offered in the CS4382A or
CS4385.
• Additional resistors on MUTEC pins
1.3 What the CS4385 offers over the CS4382A:
• Additional DSD functions of Volume control, Mute pattern detect, support for phase modulation mode, and
offers a direct to switched capacitor path.
• 1/2 dB volume control steps (vs. 1 dB in CS4382/82A)
• One-Line and TDM modes
• Auto-mute polarity detection
• Auto-speed mode detection
1.4 Changes from the CS4382 that the CS4385 requires:
• The VD supply must be changed to 2.5 V from the either 3.3 V or 5 V of the CS4382
• Depending on the desired output voltage requirements, attenuation may need to be added to the off-chip filter.
• Simultaneous support for two synchronous sample rates is no longer available
• Additional resistors on MUTEC pins
• 4 pins change location or function for hardware mode. The changes aren't necessary for software mode.
• Requires different register mapping from the CS4382
JAN ‘09
AN259REV2