CS43130 Datasheet, PDF (87/137 Pages) Cirrus Logic – 130-dB, 32-Bit High-Performance DAC with Integrated Headphone Driver

CS43130
5.11 Headphone Load Measurement
5.11.3 Measuring AC Impedance at 1 kHz
Fig. 5-4 shows and Ex. 5-22 describes the steps necessary to measure AC impedance at 1 kHz with the following
assumptions:
• Continuing from Step 11 of Ex. 5-21 since DC impedance measurement is required to be run before AC impedance
measurement.
Enable Impedance Measurement
Subsystem has already been run.
DC Impedance Measurement has
already been run at least once.
AC Impedance Measurement
DC Impedance Measurement
Set Frequency
NO
HPLOAD _DC_ ONCE
YES HPLOAD_MEAS _FREQ_LSB = 0x??
= 1?
HPLOAD _MEAS_FREQ_ MSB = 0 x??
A
Select Channel A
0x10010 = 0x99
0x10026 = 0x0A
0x10027 = 0x93
0x10028 = 0x0A
0x10010 = 0x00
HPLOAD_ CHN_SEL = 0 (Channel A )
HPLOAD _AC_START = 0 (Stop)
Channel ?
B
Select Channel B
0x10010 = 0x99
0x10026 = 0x8A
0x10027 = 0x15
0x10028 = 0x06
0x10010 = 0x00
HPLOAD_ CHN_SEL = 1 (Channel B )
HPLOAD _AC_START = 0 (Stop)
Enable DC impedance measurement
HPLOAD _AC_START = 1
Assumptions
DAC Response
User Commands
HPLOAD_ AC_DONE_INT
= 1?
NO
YES
NO
HPLOAD_UNPLUG_ INT
= 1?
YES
HPLOAD_ UNPLUG_INT NO
= 1?
Read AC impedance
HPLOAD_OOR _INT
= 1?
NO
value from
RL_AC_STAT_0 and
RL_AC_STAT_ 1
YES
Error Occurred
YES
New
Measurement?
NO
YES
Disable Impedance Measurement
Subsystem
Disable Impedance Measurement Subsystem
Figure 5-4. AC Impedance Measurement Flowchart
Example 5-22. AC Impedance Measurement at 1 kHz
STEP
TASK
REGISTER/BIT FIELDS
1 Enable impedance measurement subsystem. Refer to Ex. 5-20.
VALUE
DESCRIPTION
2 Check if DC impedance was already measured. Read HP Load Status (0xE001A) and verify HPLOAD_DC_ONCE (bit 8) is set.
3 Measure headphone AC impedance
4 Select Channel A
0x10010
0x99
0x10026
0x0A
0x10027
0x93
0x10028
0x0A
0x10010
0x00
HP Load 1. 0xE0000
0x80
HPLOAD_EN
Reserved
HPLOAD_CHN_SEL
Reserved
HPLOAD_AC_START
HPLOAD_DC_START
1
00
0
HPOUTA selected
00
0
0
DS1073F1
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