STA304 STMicroelectronics, STA304 Datasheet - Page 14

• Manufacturer Part Number: STA304
• Description: Audio DSPs Digital Audio Proc
• Manufacturer: STMicroelectronics

Specifications of STA304

• Mounting Style: SMD/SMT
• Package / Case: TQFP-44
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

STA304
Figure 7. Powerdown management
In order to avoid any possible pop-noise while switching between the various powerdown modes a particular
masking technique has been adopted to drive the actual controlling signals: as shown in the above figure the 3
powerdown requests will inform the DSP using the related bits in specific registers. After that the DSP performs
a software fade-out of the channels volume and, finally, activates the MUTE flags of the various channels.
The actual controlling lines are the result of a logical AND operation between the relative request signals and
the 4 channel MUTE bits (LR, LFE, SL and SR).
Moreover the external power chip will be turned off (via the EAPD pin) not only as a consequence of an EAPD request,
but also as a consequence of a PR5 or PWDN requests: this solution will prevent any possible noise or glitch.
14/31
EAPD (reg. 26h, bit 15)
PWDN pin (reg.7EFh, bit0)
(Active Low)
PR5 (reg.26h, bit 13)
Requests
DSP
LR
LFE
SL
SR
&
OR
&
&
&
LR
LFE
SR
SL
Chip powerdown
EAPD pin (ACTIVE Low)
Internal CK disable
reg. 02h bit 15
reg. 36h bit 15
reg. 38h bit 07
reg. 38h bit 15