Cirrus Logic AN260 User Manual

AN260

Transitioning from the CS4362 to the CS4362A or CS4365

1. Introduction

This application note describes how to transition easily to the CS4365 or CS4362A from an existing design that uses the CS4362. The CS4362A was designed to give a simple upgrade path from the CS4362, whereas the CS4365 adds some additional features. Please refer to the CS4362A and CS4365 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 CS4362A offers over the CS4362:

• 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 CS4362 that the CS4362A requires:

• The VD supply must be changed to 2.5 V from either the 3.3 V or 5 V of the CS4362.

•

Depending on the desired output voltage require ments, 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 CS43 62. 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 CS4362A or CS4365.

• Additional resistors on MUTEC pins.

1.3 What the CS4365 offers over the CS4362A:

• 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 CS4362/62A)

• One-Line and TDM modes

• Auto-mute polarity detection

• Auto-speed mode detection

1.4 Changes from the CS4362 that the CS4365 requires:

• The VD supply must be changed to 2.5 V from the either 3.3 V or 5 V of the CS4362.

•

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.

• Four pins change location or function for hardware mode. The chang es aren't necessary for so ftware mode.

• Requires different register mapping from the CS4362.

http://www.cirrus.com

AN260REV2

JAN ‘09

AN260

CS4365 CS4362A CS4362 Dynamic Range THD+N Resolution Sample Rate Pow er Suppl y

Volume Control 0.5 dB Auto F s De tect Yes Package 48-LQFP

Table 1. Product Comparison

dB dB

bits

kHz

VA VD

114

-100 24

192

2.5

For users of the CS4362, the CS4365 is a simple, yet affordable, upgrade to a richer feature set and lower out-of-band noise performance.

2. The Design Transition

2.1 Transitioning from the CS4362 to CS4362A

2.1.1 Hardware changes

The CS4362A pinout was primarily based on the CS4362 with only 2 pins changing function. Other pins have new recommended components but the circuit topologies remain the same and thus do not require modification to the PCB. The most significant change is that the VD core of the CS4362A requires 2.5 V for operation, whereas the CS4362 was able to run from 3.3 V to 5 V. The CS4362A will NOT operate off of a VD supply of 3.3 V or 5 V.

Figure 1 and Figure 2 show the CS4362 and CS4362A pinouts respectively. The changes to the two pinouts are highlighted. Figure 1 highlights the pins which have changed function and which may require a PCB change. Figure 2 highlights the pins which have new recommended components.

114 114

-100 -100 24 24

192 192

2.5 3.3 to 5

1 dB 1 dB

No No

48-LQFP 48-LQFP

2 AN260REV2

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