Datasheet

OBSOLETE
LM4550
www.ti.com SNAS032F –SEPTEMBER 2001–REVISED APRIL 2013
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 impedance state to allow tester control of the AC Link interface for 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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