Cirrus Logic AN345 - Manual

Copyright  Cirrus Logic, Inc. 2010
(All Rights Reserved)
http://www.cirrus.com
Application Note
MIGRATING FROM THE CS3302 TO THE CS3302A
SEISMIC DIFFERENTIAL AMPLIFIER
1. SUMMARY
This document outlines the differences in operation of the CS3302A when compared to the CS3302
and explains how to use the CS3302A device in a system designed for the CS3302. In particular, the
need for external anti-alias filter resistors is addressed.
2. DESCRIPTION OF CHANGES BETWEEN CS3302 AND CS3302A
The CS3302A seismic differential amplifier is a pin-compatible upgrade for the original CS3302 device.
The main purpose of the CS3302A revision is to provide a fix for the two CS3302 errata listed in errata
ER596A3 (items 1 and 2 in Table 1). In addition to this fix, further upgrades were implemented in the
CS3302A. Table 1 outlines the differences between the CS3302 and CS3302A.
Although the CS3302 and CS3302A are pin-compatible devices, the CS3302A is not a drop-in replace-
ment for the CS3302. Due to the removal of internal anti-alias filters, the CS3302A requires external anti-
alias filter resistors to achieve optimum performance.
Table 1: Differences Between CS3302 and CS3302A
Item Description
1
To achieve tighter anti-alias filter resistor tolerance, CS3302A eliminates internal anti-alias filter resistors that exist in
CS3302 (specified in the CS3302 data sheet as 640 ohm ±10% depending on process parameters). This change
requires the CS3302A to use external anti-alias resistors.
2
Improved relative gain accuracy production test limits. CS3302A relative gain accuracy production test limits tight-
ened to ±0.2% maximum for all gain settings.
3 Removed unipolar power supply mode. CS3302A specified for bipolar power supply mode only.
4 Removed low power operating mode. CS3302A specified for normal power operating mode only.
5 CS3302A power supply specified operating limits tightened from ±5% to ±2%.
10
Improved typical THD performance by 1.0 dB, for gain ranges x2, x4, and x8.
Gain THD CS3302 THD CS3302A
1
-118
-118
2 -119
4 -119
8 -119
16 -118
32 -115
64 -112
AN345
SEP ‘10
AN345REV1