AK4950 Datasheet, PDF (65/106 Pages) Asahi Kasei Microsystems – 24bit Stereo CODEC with MIC/SPK/Cap-less VIDEO-AMP & mini DSP

[AK4950]
< 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 AVDD/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 AVDD/2 voltage. Because the SPP and
SPN pins rise up in power-save mode, pop noise can be reduced. When the AK4950 is powered-down (PMSPK bit =
“0”), pop noise can also be reduced by first entering power-save-mode.
PMSPK
0
1
SPPSN
x
0
1
Mode
SPP
SPN
Power-down
Hi-Z
Hi-Z
Power-save
Hi-Z
AVDD/2
Normal Operation Normal Operation Normal Operation
Table 53 Speaker-Amp Mode Setting (x: Don’t care)
(default)
PMSPK bit
SPPSN bit
>1ms
SPP pin
Hi-Z
Hi-Z
SPN pin Hi-Z ^AVDD/2
AVDD/2
Hi-Z
Figure 48. 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 speaker
amplifier is automatically powered down and then THDET bit becomes “1”(thermal shutdown). When the thermal
shutdown is executed, the speaker amplifier, lineout amplifier, charge pump and video block are powered-down
(PMSPK=PMLO=PMCP=PMV bits = “1” → “0”). Writing “1” to these registers can put each circuit in normal operation,
but it may be powered down again (“1” → “0”) if the internal temperature of the device is still high. The device status can
be monitored on THDET bit.
MS1320-E-00
- 65 -
2011/10