lm4549b National Semiconductor Corporation, lm4549b Datasheet - Page 27

• Manufacturer Part Number: lm4549b
• Description: Ac ?97 Rev 2.1 Multi-channel Audio Codec With Sample Rate Conversion And National 3d Sound
• Manufacturer: National Semiconductor Corporation

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 9. Multiple Codecs using Extended AC Link
27
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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