MAX13301 Datasheet, PDF (21/37 Pages) Maxim Integrated Products – 4-Channel, Automotive Class D Audio Amplifier Feedback After the Filter

4-Channel, Automotive Class D Audio Amplifier
Table 11. Control Register 3
CTRL3
BIT #
NAME
POR
7
6
5
4
3
2
1
0
TW
RDET
SDET
DIS
—
HCL
—
LDM
0
0
0
0
0
0
0
0
Table 12. Control Register 3 Bit Description
BIT
BIT DESCRIPTION
Tweeter-Detect Current Threshold Setting
0 = The current threshold at which OSTAT1.LOAD[3:0] (load indicator bit) asserts is set equal to the shorted-
load current threshold (see the Electrical Characteristics table). Use this setting when running shorted-load
TW
diagnostic.
1 = The current threshold at which OSTAT1.LOAD[3:0] asserts is set equal to the tweeter detect current
threshold. This threshold is approximately 25% of the default value to facilitate tweeter detection. Use this
setting when the running tweeter diagnostic or for detecting the presence of a speaker.
RDET
Open-Load Diagnostic Enable. Upon detecting an open load on any of the outputs, the corresponding
OSTAT1.LDOK[3:0] (load OK indicator bit) asserts. Always perform short-to-ground and short-to-battery
diagnosis before entering RDET mode. If a short-to-battery is detected, do not enter RDET mode. After
performing the short-to-battery test, discharge both outputs by setting CTRL3.DIS to 1 for 200µs, then reset
CTRL3.DIS back to 0. Failure to follow this procedure can result in a loud pop at the speaker.
Because the results are not latched, read LDOK[3:0] before clearing RDET. Wait a minimum of 200µs before
reading these status bits. RDET can only be set after three-stating all four outputs. When performing the
open-load diagnostic, set the CTRL3.SDET (short-to-ground/battery enable) bit to 0.
0 = Disable open-load diagnostic
1 = Enable open-load diagnostic
SDET
Short-to-Ground/Battery Diagnostic Enable. Upon detecting a short-to-ground or battery on any of the outputs,
the corresponding OSTAT2.SBAT[3:0] (short-to-battery) and OSTAT2.SGND[3:0] (short-to-ground) bits assert.
Because the results are not latched, read OSTAT2.SBAT[3:0] and OSTAT2.SGND[3:0] before clearing SDET.
Wait a minimum of 200µs before reading these status bits. Before setting SDET to 1, three-state all four out-
puts and set the CTRL3.DIS (discharge output enable) bit to 1 and then reset back to 0. Before performing
the short-to-ground/battery diagnostic, set the CTRL3.RDET (open-load diagnostic enable) bit to 0. To test for
short-to-ground, set CTRL2.STBY to 0, and to test for short-to-battery, set CTRL2.STBY to 1.
0 = Disable short-to-ground/battery diagnostic
1 = Enable short-to-ground/battery diagnostic
Discharge Output Enable. Set DIS to 1 to discharge all outputs with 15mA current sources. Use DIS to dis-
charge all outputs before performing the short-to-ground/battery diagnostic (SDET) to avoid a loud pop on
DIS
the speaker. DIS can only be set to 1 after three-stating all four outputs.
0 = Output discharge is disabled.
1 = Output discharge is enabled.
HCL
Current-Limit Level. HCL sets the current-limit threshold of the outputs during normal operation.
0 = 7A (typ) current limit
1 = 8.75A (typ) current limit
LDM
Line-Driver Mode. Use LDM to set the load resistance threshold required to assert the OSTAT1.LDOK[3:0]
(load-okay indicator bit). Any load with a resistance greater than the threshold is interpreted as an open
output.
0 = Line-driver mode, OSTAT1.LDOK[3:0] = 1 if RL > 300I
1 = Power amplifier mode, OSTAT1.LDOK[3:0] = 1 if RL > 100I
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