92hd83 Integrated Device Technology, 92hd83 Datasheet - Page 29

• Manufacturer Part Number: 92hd83
• Description: Single Chip Pc Audio System Codec+speaker Amplifier+capless Hp+ldo
• Manufacturer: Integrated Device Technology

SINGLE CHIP PC AUDIO SYSTEM, CODEC+SPEAKER AMPLIFIER+CAPLESS HP+LDO
92HD83
SINGLE CHIP PC AUDIO SYSTEM, CODEC+SPEAKER AMPLIFIER+CAPLESS HP+LDO
2.17. BTL Amplifier
2.18. EAPD
Headphone performance will degrade if more than one port is driving a 32 ohm load.
An integrated class-AB stereo BTL amplifier is provided to directly drive 4 ohm speakers (2W @
4.75V) or 8 ohm speakers (1W @ 4.75V). No external filter is needed for cable runs of 18” or less.
An internal DC blocking filter prevents distortion when the audio source has DC content, and pre-
vents unintentional power consumption when pausing audio playback. The amplifier may be con-
trolled using the EAPD pin (see EAPD section.)
Using a vendor specific verb, the BTL amplifier may be configured to support a mono speaker con-
nected to the L +/- pins. In this mode, the Left and Right audio is mixed and sent to the left output
only. The right channel is turned off to conserve power.
The BTL amplifier includes thermal management circuitry. When the CODEC reaches a temperature
of about 135 degrees, the output amplitude of the BTL amp is gradually lowered until the tempera-
ture falls below 135.
Maximum gain for the BTL amplifier is programmable. The following 4 gain settings relative to a
nominal line output are desired: +6.5dB, +9.5dB, +14.5dB and +16.5dB. Absolute gain may vary and
the suggested accuracy is +/-1.5dB. The gain is exposed in a vendor specific widget and is intended
to mimic the pin programmable gain implemented in discrete BTL amplifiers commonly used in note-
book computers.
The EAPD pin (pin 47) is a dedicated, bi-directional control pin. Although named External Amplifier
Power Down (EAPD) by the HD Audio specification, this pin operates as an external amplifier power
up signal. The EAPD value is reflected on the EAPD pin; a 1 causes the external amplifier to power
up (equivalent to D0), and a 0 causes it to power down (equivalent to D3.) When the EAPD value =
1, the EAPD pin must be placed in a state appropriate to the current power state of the associated
Pin Widget even though the EAPD value (in the register) may remain 1. The default state of this pin
is 0 (driving low.) The pin defaults to an open-drain configuration (an external pull-up is recom-
mended.)
Per the HD Audio specification and ECR15b, multiple ports may control EAPD. The EAPD pin
assumes the highest power state of all the EAPD bits in all of the pin complexes. The default value of
EAPD is 1 (powered on), but the FG power state will override and the pin will be low. A port will
request External Amp Power Up when its power state is active (FG and pin widget power state is D1
or D0) or (Analog PC_Beep is enabled and port is enabled as an output) and the port’s EAPD bit is
set to 1. The state of the EAPD pin (unless configured as an input or held low by an external circuit
when configured as an open drain output) will be the logical OR of the external amp power up
requests from all ports.
By default, the EAPD pin also functions as the Mute#/ShutDown# input for the internal BTL amplifier.
In this mode, a low value at the pin (either due to internal EAPD being 0, or to an external entity forc-
ing the pin low) will cause the internal BTL amplifier to mute or enter a low power state depending on
the amplifier configuration. (See below)
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92HD83
PC AUDIO
V 0.96 01/09