92HD87 Datasheet, PDF (27/204 Pages) Integrated Device Technology – SINGLE CHIP PC AUDIO SYSTEM

92HD87
SINGLE CHIP PC AUDIO SYSTEM, CODEC+STEREO SPEAKER AMPLIFIER+CAPLESS HP+LDO
The filter is implemented in digital before the Digital to Analog converter. There are 2 major conse-
quences to implementing the filter in the digital domain:
1. All ports connected to the DAC will be affected by the high-pass filer when it is enabled.
2. Analog paths (such as when the microphone input is routed through the mixer to the BTL ampli-
fier) are not affected.
Like the other analog inputs, PC_Beep is not affected by the digital high-pass filter. To ensure that
the speakers attached to the BTL amplifier are not harmed by low frequency audio entering the
PC_Beep input, an external filter must be implemented. Fortunately, it is common practice to imple-
ment an attenuation circuit and DC blocking capacitor at the PC_Beep input. This attenuator/filter is
easily adjusted to restrict low frequency audio. The easiest approach is to reduce the value of the
DC blocking capacitor but other approaches are equally effective.
2.19. GPIO
2.19.1. GPIO Pin mapping and shared functions
GPIO Pin
#
12
23
Supply GPI/O GPI GP VrefOut DMIC VOL Pull
O
Up
DVDD YES
CLK
DVDD YES
IN
Pull
Down
50K
50K
2.19.2. Digital Microphone/GPIO Selection
2 functions are available on the DMIC_CLK/GPIO1 (pin 2) and the DMIC_0/GPIO2 (pin 3) pins. To
determine which function is enabled, the order of precedence is followed:
1. If GPIOs are not enabled through the AFG, then at reset, pins 2 and 4 are pulled low by an inter-
nal pull-down resistor.
2. If the GPIO 1 is enabled, the 2 DMIC pins become mute (unless programmed for GPIO use) and
pin 2 becomes an internal pull-down.
3. If GPIO2 is enabled through the AFG, pin 3 becomes a GPIO and is pulled low by an internal
pull-down resistor.
4. If the port is enabled as an input, the digital microphones will be used.
5. If the port is not enabled as an input or if the pin is configured as a GPIO, the digital microphone
path will be mute.
2.20. HD Audio HDA015-B support
Although HDA015-B is not yet complete (not a DCN), the 92HD87 will implement complete support
for the specification building on the support already present in previous products. HDA015-B fea-
tures supported are:
• Persistence of many configuration options through bus and function group reset.
• The ability to support port presence detect in D3 even when the HD Audio bus is in a low power
state (no clock.)
• Fast resume times from low power states: 1ms D1 to D0, 2ms D2 to D0, 10mS D3 to D0.
• Notification if persistent register settings have been unexpectedly reset.
IDT CONFIDENTIAL
27
©2009 INTEGRATED DEVICE TECHNOLOGY, INC.
V 0.995 01/11
92HD87