92HD66B Datasheet, PDF (29/286 Pages) Integrated Device Technology – FOUR CHANNEL HD AUDIO CODECS

92HD66B
FOUR CHANNEL HD AUDIO CODECS WITH DUAL CAPLESS HEADPHONE AMPLIFIERS
Analog PC-Beep may also be supported during HD-Link Reset if analog PC_Beep is manually
enabled before entering reset. Analog PC_Beep is mixed at the port and only ports enabled as out-
puts will pass PC_Beep. Analog PC_Beep (or a digital equivalent) must not prevent passing WLP
when analog PC_Beep is enabled. Analog PC_Beep, when enabled, must not prevent other audio
sources from playing (we must mix not mux.) Beeps from ICH (from Beep.sys) can have a frequency
of about 37Hz to about 32KHz. Beep duration is programmable from 1mS to about 32 seconds. A
typical beep under Windows XP is 500Hz or 2KHz and lasts 75ms or 150mS. Due to external XOR
gates used as mixers, the idle state may be logic 0 or logic 1.
PC-Beep may be attenuated and distorted when the CODEC is in D3 depending on the load imped-
ance seen by the output amplifier since all ports are in a low power state while in D3. Load imped-
ances of 10K or larger can support full scale outputs but lower impedance loads will distort unless
the output amplitude is reduced.
Analog PC_Beep is not supported in D3 Cold, or the vendor specific states D4/D5.
Analog PC_Beep is typically used during POST to route error beep codes to internal speakers for
diagnostic purposes. When using a legacy OS such as DOS, analog PC_Beep routes “Bell” and
“Alarm” tones from the south bridge to internal speakers or headphones. Keyboard controller “Key-
click” sounds are also routed to internal speakers using the analog beep function in both Windows
and legacy operating systems.
2.20.1. PC_Beep Activity Monitor
An activity monitor will allow the cap-less headphone amplifiers to remain in shutdown when the
function group is in D3 until the beep pin is active and then quickly change to an active state (within
10mS) to pass the beep tone.
Beep activity monitoring is only required when the analog beep path is enabled and the CODEC or
amplifier is in a low power state (D3).
2.20.1.1. Input Characteristics:
• There is no correlation between frequency of the tone and duration of the tone.
• There will always be at least one complete cycle
• A minimum input level of -23dBV (200mVpp) is required for proper detection. (Inputs are typi-
cally driven by 3.3V CMOS logic followed by 12-20dB attenuation and filtering)
• Beeps from ICH (from Beep.sys) can have a frequency of about 37Hz to about 32KHz and are
1-bit (PFM)
• Beeps from the Keyboard or system management controller are typically PWM (rate unknown
but typically 48KHz or less.)
• Beep duration may be from 1mS to ~32 seconds if provided by ICH under OS control.
• A typical beep under Windows XP is 500Hz or 2KHz and lasts 75ms or 150mS
• Due to external XOR gates used as mixers, the idle state may be logic 0 or logic 1
2.20.1.2. Firmware/Software Requirements:
The reconfiguration outlined in this chapter must be enabled by default (without the help of firmware
or OS driver.)
This autonomous mode must not interfere with normal operation.
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