LM4550B National Semiconductor Corporation, LM4550B Datasheet - Page 30

• Manufacturer Part Number: LM4550B
• Description: Ac 97 Rev 2.1 Multi-channel Audio Codec With Stereo Headphone Amplifier, Sample Rate Conversion And National 3d Sound
• Manufacturer: National Semiconductor Corporation

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Multiple Codecs
Test Modes
AC ’97 Rev 2.1 defines two test modes: ATE test mode and
Vendor test mode. Cold Reset is the only way to exit either of
them. The ATE test mode is activated if SDATA_OUT is
sampled high by the trailing edge (zero-to-one transition) of
RESET#. In ATE test mode the codec AC Link outputs
SDATA_IN and BIT_CLK are configured to a high imped-
ance state to allow tester control of the AC Link interface for
(Continued)
FIGURE 10. Multiple Codecs in a Chain
30
controller testing. ATE test mode timing parameters are
given in the Electrical Characteristics table. The Vendor test
mode is entered if SYNC is sampled high by the zero-to-one
transition of RESET#. Neither of these entry conditions can
occur in normal AC Link operation but care must be taken to
avoid mistaken activation of the test modes when using non
standard controllers.
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