MAX9888EWY+T Maxim Integrated Products, MAX9888EWY+T Datasheet - Page 93

• Manufacturer Part Number: MAX9888EWY+T
• Description: IC CODEC AUDIO FLEXSOUND 63WLP
• Manufacturer: Maxim Integrated Products
• Series: DirectDrive®, FLEXSOUND™r
• Type: Class Dr

Specifications of MAX9888EWY+T

• Output Type: 3-Channel with Stereo Headphones
• Max Output Power X Channels @ Load: 1.37W x 2 @ 8 Ohm; 40mW x 2 @ 16 Ohm
• Voltage - Supply: 2.8 V ~ 5.5 V
• Features: Depop, Differential Inputs, I²S, Microphone, Mute, Shutdown
• Mounting Type: Surface Mount
• Package / Case: 63-WLP
• For Use With: MAX9888EVKIT+ - KIT EVALUATION FOR MAX9888
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The IC’s power limiter tracks the RMS power delivered to
the loudspeaker and briefly mutes the speaker amplifier
output if the speaker is at risk of sustaining permanent
damage.
Loudspeakers are typically damaged when the voice coil
overheats due to extended operation above the rated
power. During normal operation, heat generated in the
voice coil is transferred to the speaker’s magnet, which
transfers heat to the surrounding air. For the voice coil to
overheat, both the voice coil and the magnet must over-
heat. The result is that a loudspeaker can operate above
its rated power for a significant time before it heats suf-
ficiently to cause damage.
Table 26. Power Limiter Registers
REGISTER
REGISTER
0x42
BIT
BIT
7
6
5
4
2
1
0
PWRTH
NAME
NAME
PWRK
Power Limiter Threshold
If the RMS output power from the speaker amplifiers exceeds this threshold, the out-
put is briefly muted to protect the speaker. The threshold is measured in watts assum-
ing an 8I load. VBAT must correctly reflect the voltage of SPKLVDD/SPKRVDD to
achieve accurate thresholds.
Power Limiter Weighting Factor
Determines the balance between time constant 1 and 2 to match the dominance of
each time constant in the loudspeaker.
Power Limiter
with FLEXSOUND Technology
VALUE
VALUE
0x0
0x1
0x2
0x3
0x4
0x5
0x6
0x7
000
001
010
011
100
101
110
111
The IC’s power limiter includes user-programmable time
constants and power thresholds to match a wide range
of loudspeakers. Program the power limiter’s threshold to
match the loudspeaker’s rated power handling. This can
be determined through measurement or the loudspeak-
er’s specification. Program time constant 1 to match the
voice coil’s thermal time constant. Program time constant
2 to match the magnet’s thermal time constant. The time
constants can be determined by plotting the voice coil’s
resistance vs. time as power is applied to the speaker.
THRESHOLD
Stereo Audio CODEC
Power limiter
disabled
0.05
0.06
0.09
0.11
0.13
0.18
0.22
(W)
DESCRIPTION
DESCRIPTION
T1 (%)
62.5
87.5
12.5
37.5
100
50
75
25
VALUE
0xA
0xB
0xC
0xD
0x8
0x9
0xE
0xF
T2 (%)
37.5
12.5
87.5
62.5
THRESHOLD
50
25
75
0
0.27
0.35
0.48
0.72
1.00
1.43
1.57
1.80
(W)
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