92HD91 Datasheet, PDF (27/298 Pages) Integrated Device Technology – SINGLE CHIP PC AUDIO SYSTEM

92HD91
SINGLE CHIP PC AUDIO SYSTEM, CODEC+SPEAKER AMPLIFIER+CAPLESS HP+LDO
Figure 4. EAPD implementation
Internal
Headphone
Amp
SD/Mute
Internal BTL
Amp
SD/Mute
EAPD
VDD
EAPD PIN
Control
CODEC
SMU MUTE
OTHER
SD#
External
Power Amp
2.15. Digital Microphone Support
The digital microphone interface permits connection of a digital microphone(s) to the CODEC via the
DMIC0, DMIC1, and DMIC_CLK 3-pin interface. The DMIC0 and DMIC1 signals are inputs that carry
individual channels of digital microphone data to the ADC. In the event that a single microphone is
used, the data is ported to both ADC channels. This mode is selected using a vendor specific verb
and the left time slot is copied to the ADC left and right inputs.
The DMIC_CLK output is controllable from 4.704Mhz, 3.528Mhz, 2.352Mhz, 1.176Mhz and is syn-
chronous to the internal master clock. The default frequency is 2.352Mhz.
The two DMIC data inputs are reported as two stereo input pin widgets that incorporate a boost
amplifier. The pin widgets are shown connected to the ADCs through the same multiplexors as the
analog ports. Although the internal implementation is different between the analog ports and the dig-
ital microphones, the functionality is the same. In most cases, the default values for the DMIC clock
rate and data sample phase will be appropriate and an audio driver will be able to configure and use
the digital microphones exactly like an analog microphone.
To conserve power, the analog portion of the ADC will be turned off if the D-mic input is selected.
When switching from the digital microphone to an analog input to the ADC, the analog portion of the
ADC will be brought back to a full power state and allowed to stabilize before switching from the dig-
ital microphone to the analog input. This should take less than 10mS.
DMIC pin widgets support port presence detect directly using SENSE-B input.
IDT™ CONFIDENTIAL
27
©2009 INTEGRATED DEVICE TECHNOLOGY, INC.
V 1.2 1/12
92HD91