AK4955 Datasheet, PDF (65/117 Pages) Asahi Kasei Microsystems – 24bit Stereo CODEC with MIC/SPK/Cap-less VIDEO-AMP/ LDO & DSP

[AK4955]
< Speaker-Amp Control Sequence >
The speaker amplifier is powered-up/down by PMSPK bit. When PMSPK bit is “0”, both SPP and SPN pins are in Hi-Z
state. When PMSPK bit is “1” and SPPSN bit is “0”, the speaker amplifier enters power-save mode. In this mode, the SPP
pin is placed in Hi-Z state and the SPN pin outputs SVDD/2 voltage.
When the PMSPK bit is “1” after the PDN pin is changed from “L” to “H”, the SPP and SPN pins rise up in power-save
mode. In this mode, the SPP pin is placed in a Hi-Z state and the SPN pin goes to SVDD/2 voltage. Because the SPP and
SPN pins rise up in power-save mode, pop noise can be reduced. When the AK4955 is powered-down (PMSPK bit =
“0”), pop noise can also be reduced by first entering power-save-mode.
PMSPK bit
0
1
SPPSN bit
Mode
SPP pin
SPN pin
x
Power-down
Hi-Z
Hi-Z
0
Power-save
Hi-Z
SVDD/2
1
Normal Operation Normal Operation Normal Operation
Table 62 Speaker-Amp Mode Setting (x: Don’t care)
(default)
PMSPK bit
SPPSN bit
>1ms
(Recommended Value)
>0
(Recommended Value)
SPP pin
Hi-Z
SPN pin Hi-Z ^SVDD/2
Hi-Z
SVDD/2
Hi-Z
Figure 51. Power-up/Power-down Timing for Speaker-Amp
■ Thermal Shutdown Function
When the internal temperature of the device rises up irregularly (e.g. when output pins are shortened), the thermal
shutdown is executed, all blocks except VCOM and LDO blocks are powered-down, and THDET bit becomes “1”. These
blocks will not return to normal operation until being reset by the PDN pin. The thermal shutdown status can be
monitored by reading THDET bit. THDET bit becomes “0” by this PDN pin reset.
MS1343-E-00
- 65 -
2011/12