MAXIM MAX13301 Technical data

19-5955; Rev 0; 6/11
EVALUATION KIT
AVAILABLE
4-Channel, Automotive Class D Audio Amplifier
General Description
The MAX13301 combines four high-efficiency Class D amplifiers with integrated diagnostic hardware for reli­able automotive audio systems, and delivers up to 80W at 10% THD+N per channel into 4I when operating from a 24V supply.
The internal diagnostics evaluate each channel’s output impedance to check for shorts across the outputs, to the battery, or to ground. The I2C interface allows the sys­tem to query critical device parameters such as device temperature and output clipping. The device is program­mable to four different I2C addresses.
The audio amplifiers feature single-ended analog inputs with a common negative input. The MAX13301 has a fixed gain of 26dB.
The Class D amplifier has 10 programmable switching frequencies between 300kHz and 750kHz.
The BTL outputs are protected against short circuits and thermal overload. The outputs can be configured as a 2-, 3-, or 4-channel amplifier. The device provides 50V load-dump protection, and is offered in the thermally enhanced, 48-pin TSSOP-EPR package operating over the -40NC to +125NC temperature range.
Applications
Car Stereo
Rear-Seat Entertainment Units
Discrete Amplifier Modules
Active Loudspeaker Systems
Radio Head Units
Mobile Surround Systems
Features
S High Output Power (10% THD+N)
2 x 160W into 2I at 24V4 x 80W into 4I at 24V
S 2 Channels Can Be Paralleled S Feedback After the Filter
Improves THD+NLow Output ImpedanceHigh-Frequency ResponseImproved Damping of Complex LoadsEnables Low-Cost Inductors
S 102dB SNR S Low 0.04% THD+N S 70dB PSRR S On-Board Diagnostics
Short-to-Battery/GNDOpen/Shorted LoadTweeter Detect
S Protection and Monitoring Functions:
Short-Circuit Protection50V Load-Dump ProtectionProgrammable Clip DetectionDC Offset DetectionOpen Battery/GND TolerantThermal-Overload ProtectionThermal Warning Indication
S Four-Address I2C Control Interface S Low-Power Shutdown Mode S Up to 90.5% Efficiency S -40°C to +125°C Ambient Operating Temperature S 48-Pin TSSOP-EPR (Top Side Exposed Pad) Package S AEC-Q100 Qualified
MAX13301
Ordering Information
PART PIN-PACKAGE
Typical Operating Circuit appears at end of data sheet.
MAX13301AUM/V+ 48 TSSOP-EPR* 6 to 25.5
Note: The device operates over the -40°C to +125°C operating temperature range. /V denotes an automotive qualified part.
+Denotes a lead(Pb)-free/RoHS-compliant package. *EPR = Top side exposed pad.
_______________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
SUPPLY VOLTAGE
RANGE (V)
4-Channel, Automotive Class D Audio Amplifier
ABSOLUTE MAXIMUM RATINGS
PVDD to PGND ......................................................-0.3V to +30V
PVDD to PGND (t < 200ms) ..................................-0.3V to +50V
V
, CM to PGND ................................................. -0.3V to +6V
DD5
CP to PGND ........................(V
CHOLD to PVDD .....................................................-0.3V to +6V
OUT_ to PGND, FB_ to PGND ..............-0.3V to (V
VDD to GND ............................................................-0.3V to +6V
REF to GND ............................................................. -0.3V to +6V
MAX13301
SCL, SDA, SYNC to GND ........................................-0.3V to +6V
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
- 0.3V) to (V
PVDD
CHOLD
PVDD
+ 0.3V)
+ 0.3V)
PACKAGE THERMAL CHARACTERISTICS (Notes 1 and 2)
TSSOP
Junction-to-Ambient Thermal Resistance (BJA) ..........60NC/W
Junction-to-Case Thermal Resistance (BJC) .................1NC/W
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-
layer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.
Note 2: The 48-pin TSSOP-EPR package has a top side exposed pad for enhanced thermal management. Connect this exposed
pad to an external heatsink to ensure the device is adequately cooled. The maximum power dissipation in the device is a function of this external heatsink and other system parameters. See the Thermal Information section for more information.
MUTE_CL1, CL0, FLT_OT, EN to GND ...................-0.3V to +6V
IN_ to GND ..............................................................-0.3V to +6V
GND to PGND ......................................................-0.3V to +0.3V
Continuous Power Dissipation (Notes 1 and 2)
TSSOP (derate 16.7mW/NC above 70NC) ...............1333.3mW
Operating Temperature Range ........................ -40NC to +125NC
ELECTRICAL CHARACTERISTICS
(V
= 14.4V, VDD = V
PVDD
TA = -40NC to +125NC; typical values are at TA = +25NC, unless otherwise noted.) (Note 3)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
AMPLIFIER DC CHARACTERISTICS
Supply Voltage Range
PVDD UVLO Threshold Falling 5.2 5.35 5.6 V
PVDD OVLO Threshold Rising 26 27 30 V
PVDD OVLO Response Timing Rising 4 14 55
OUT_ and FB_ Voltage OV active V
VDD UV Threshold
VDD UV Threshold Hysteresis 0.1 0.2 V
VDD UV Threshold Deglitch 1
Quiescent Supply Current
DD5
= 5V, V
GND
V
PVDD
V
DD5
V
I
PVDD
I
VDD5
I
VDD
= V
DD
= 0V, fSW = 500kHz, MAP.COMP[2:0] = (see Table 20 for applicable setting),
PGND
8 25.5
Operational 6
4.75 5 5.5
4.5 5 5.5
Falling 4.2 4.35
Rising 4.5 4.6
RL = J, play mode (CTRL2 = 0x0F)
/2 V
PVDD
70
60 72
50 75
V
Fs
V
Fs
FA
mA
2
4-Channel, Automotive Class D Audio Amplifier
ELECTRICAL CHARACTERISTICS (continued)
(V
= 14.4V, VDD = V
PVDD
TA = -40NC to +125NC; typical values are at TA = +25NC, unless otherwise noted.) (Note 3)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
PVDD Shutdown Supply Current
V
Shutdown Supply Current
DD5
VDD Shutdown Supply Current I
Standby Supply Current
Output Leakage
Output Discharge Current CTRL3.DIS = 1 8 mA
R
per Output Excluding wire bond resistance 70
DS(ON)
FB_ Resistance 310
Output Offset V
OUT_ Output Impedance 100
AMPLIFIER AC CHARACTERISTICS
Output Power P
Signal-Path Gain 26 dB
Channel-to-Channel Gain Tracking
Input Resistance
Mute Attenuation
Precharge Current CTRL1.PRE = 1
Power-Supply Rejection Ratio
REF Voltage C
REF Output Impedance DC 800
Input Voltage Range AC-coupled 1.2 V
DD5
= 5V, V
= V
GND
I
PVDD_ SHDN
I
VDD5_ SHDN
VDD_SHDN
I
VDD5
I
VDD
OS
OUT
= 0V, fSW = 500kHz, MAP.COMP[2:0] = (see Table 20 for applicable setting),
PGND
TA = +25NC, VEN = 0V
TA = T
to +85NC, VEN = 0V
MIN
TA = +25NC, VEN = 0V
TA = T
to +85NC, VEN = 0V
MIN
TA = +25NC, VEN = 0V
TA = T
to +85NC, VEN = 0V
MIN
CTRL2 = 0x20, VEN = 5V
V
= 14.4V 200
OUT_
V
= 0V 1
OUT_
TA = +25NC, mute mode (CTRL2 = 0x00), no input signal
TA = T
THD+N = 1%, RL = 4I, V
THD+N = 10%, RL = 4I, V
THD+N = 10%, RL = 2I, V
MIN
to T
MAX
PVDD
PVDD
PVDD
= 24V
= 24V
= 24V,
parallel mode
7
17
0.1
2
0.1
2
1
10
15
100
66
80
160
-1 +0.1 +1 dB
IN0+, IN1+, IN2+, IN3+ 20
IN- 5
Guaranteed by design, test is functional only
90 100 dB
IN- 5 10
IN_+ 1 2
VDD = 4.5V to 5.5V 70
V
= 1V
PVDD
V
= 8V to 25.5V 68
PVDD
REF(MIN)
ripple, 100Hz to 10kHz 60
P-P
= 1µF 2.224 V
FA
FA
FA
mA
FA
mI
kI
mV
mI
W
kI
mA
dB
I
RMS
MAX13301
3
4-Channel, Automotive Class D Audio Amplifier
ELECTRICAL CHARACTERISTICS (continued)
(V
= 14.4V, VDD = V
PVDD
TA = -40NC to +125NC; typical values are at TA = +25NC, unless otherwise noted.) (Note 3)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Total Harmonic Distortion Plus Noise
MAX13301
Noise N
Crosstalk P
Efficiency
Internal Switching Frequency Adjust Range
ONE-TIME DIAGNOSTICS
Short-to-Ground Detection CTRL2.STBY = 0, CTRL3.SDET = 1 75
Short-to-PVDD Detection Threshold
Open-Load Detection
Low-Current Threshold
High-Current Threshold
CONTINUOUS DIAGNOSTICS
Differential Output Offset Voltage Threshold
Clip-Detect Threshold
DD5
= 5V, V
= V
GND
THD+N
E
= 0V, fSW = 500kHz, MAP.COMP[2:0] = (see Table 20 for applicable setting),
PGND
P
= 10W, RL = 4I, BW = 22Hz to
OUT
20kHz AES17 filter, f = 1kHz
P
= 1W to 10W, RL = 4I, BW = 22Hz
OUT
to 20kHz AES17 filter, f = 1kHz
A-weighted, V
22Hz to 22kHz, V
A-weighted, CTRL5.SS[2:0] = 110, SSEN = 1, V
= 4W, f = 1kHz to 10kHz 60 dB
OUT_
RL = 4I, P VDD supplied from a switching power supply
6 to 15 clock-divider range 300 750 kHz
CTRL2.STBY = 1, CTRL3.SDET = 1 6 V
CTRL3.LDM = 1, power amplifier mode 70 100
CTRL3.LDM = 0, line-driver mode 200 300
15kHz < f < 25kHz, TA = +25NC, CTRL3.TW = 1
f < 20Hz, CTRL3.TW = 0
No audio in play mode 0.56 1.04 1.6 V
RL = 4I
OUT
= 24V 100
PVDD
= 24V 140
PVDD
= 24V
PVDD
= 20W/channel, V
CTRL3.HCL = 0 160 291 500
CTRL3.HCL = 1 200 364 625
CTRL3.HCL = 0 0.65 1.15 1.85
CTRL3.HCL = 1 0.9 1.65 2.15
CTRL1.CLVL[1:0] = 11
CTRL1.CLVL[1:0] = 01
CTRL1.CLVL[1:0] = 10
CTRL1.CLVL[1:0] = 00
DD5
,
0.04 0.14
0.1
100
88 %
1
3
5
10
%
FV
RMS
I
I
mA
A
%THDN
4
4-Channel, Automotive Class D Audio Amplifier
ELECTRICAL CHARACTERISTICS (continued)
(V
= 14.4V, VDD = V
PVDD
TA = -40NC to +125NC; typical values are at TA = +25NC, unless otherwise noted.) (Note 3)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Short-to-Ground/PVDD
Level 1 Output Current Limit I
Level 2 Output Current Limit I
THERMAL PROTECTION
Thermal Warning Range 1 Guaranteed monotonic 110
Thermal Warning Range 2 Guaranteed monotonic 120
Thermal Warning Range 3 Guaranteed monotonic 130
Thermal Warning Range 4 Guaranteed monotonic 140
Thermal Shutdown Level Guaranteed monotonic 150 165
Thermal Warning Hysteresis 5
Thermal Shutdown Hysteresis 15
CHARGE PUMP
Switching Frequency fCP = f
Soft-Start Time 100
Charge-Pump Output Impedance
Output Voltage V
INTERNAL OSCILLATOR
SYNC I/O Frequency Range 2x switching frequency 0.6 1.5 MHz
Frequency Spread-spectrum disabled 17.1 18 18.9 MHz
DIGITAL INTERFACE (SCL, SDA, ADDR, CL0, MUTE_CL1, EN, SYNC, FLT_OT)
SYNC High CTRL1.CM[1:0] = 01, I
SYNC Low CTRL1.CM[1:0] = 01, I
Input Voltage High V
Input Voltage Low V
Input Voltage Hysteresis 300 mV
Input Leakage Current
Output Low Voltage
Pulldown Current
DD5
= 5V, V
GND
LIM1
LIM2
INH
INL
= V
= 0V, fSW = 500kHz, MAP.COMP[2:0] = (see Table 20 for applicable setting),
PGND
OUT__ shorted to ground/PVDD, CTRL1.CL_TH = 1
OUT__ shorted to ground/PVDD, CTRL1.CL_TH = 0
CTRL3.HCL = 0 5.5 7 A
CTRL3.HCL = 1 7 8.75 A
SW
Guaranteed by FET R measurement
SDA, SCL, CL0, MUTE_CL1, FLT_OT SDA, CL0, MUTE_CL1, I
FLT_OT MUTE_CL1
EN 10 18
CTRL3.HCL = 0 1.03
CTRL3.HCL = 1 1.28
CTRL3.HCL = 0 3.09
CTRL3.HCL = 1 3.86
300 750 kHz
DS(ON)
SOURCE
SINK
= 3mA 4.5 V
= 3mA 0.4 V
2.0 V
= 3mA,
SINK
1.8
+ 5 V
PVDD
5 13
NC
NC
NC
NC
NC
NC
NC
Fs
I
0.8 V
Q10 FA
0.4 V
FA
MAX13301
A
5
4-Channel, Automotive Class D Audio Amplifier
ELECTRICAL CHARACTERISTICS (continued)
(V
= 14.4V, VDD = V
PVDD
TA = -40NC to +125NC; typical values are at TA = +25NC, unless otherwise noted.) (Note 3)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
I2C TIMING
Output Fall Time t
Pin Capacitance 10 pF
Clock Frequency f
MAX13301
SCL Low Time t
SCL High Time t
START Condition Hold Time t
START Condition Setup Time t
Data Hold Time t
Data Setup Time t
Input Rise Time t
Input Fall Time t
STOP Condition Setup Time t
Bus Free Time t
Maximum Bus Capacitance C
Note 3: All units are 100% production tested at TA = +25NC. All temperature limits are guaranteed by design.
DD5
= 5V, V
= V
GND
OF
SCL
LOW
HIGH
HD:STA
SU:STA
HD:DAT
SU:DAT
R
F
SU:STO
BUF
BUS
= 0V, fSW = 500kHz, MAP.COMP[2:0] = (see Table 20 for applicable setting),
PGND
C
= 10pF to 400pF 250 ns
BUS
400 kHz
1.3
0.6
Repeated START condition 0.6
Repeated START condition 0.6
0 900 ns
100 ns
SCL, SDA 300 ns
SCL, SDA 300 ns
0.6
Between START and STOP conditions 1.3
Per bus line 400 pF
Fs
Fs
Fs
Fs
Fs
Fs
6
4-Channel, Automotive Class D Audio Amplifier
Typical Operating Characteristics
(V
= 24V, VDD = V
PVDD
TA = +25NC, unless otherwise noted.)
THD+N vs. OUTPUT POWER
10
f = 1kHz BW = 22Hz TO 20kHz AES17 R
= 4I
L
1
THD+N (%)
0.1
0.01 0 80
OUTPUT POWER (W)
DD5
= 5V, V
604020
GND
= V
MAX13301 toc01
= 0V, fSW = 500kHz, MAP.COMP[2:0] = 011, see Table 32 for LC filter value,
PGND
EFFICIENCY vs. OUTPUT POWER
PER CHANNEL
RL = 4I
RL = 2I
OUTPUT POWER PER CHANNEL (W)
2-CHANNEL
PARALLEL MODE
R
= 1I
L
fIN = 1kHz 10% THD+N BW = 22Hz TO 20kHz AES17
10
1
THD+N (%)
0.1
0.01
THD+N vs. OUTPUT POWER
f = 1kHz BW = 22Hz TO 20kHz AES17 PARALLEL MODE
RL = 2I
RL = 4I
OUTPUT POWER (W)
140120100806040200 160
MAX13301 toc02
100
90
80
70
60
50
40
EFFICIENCY (%)
30
20
10
0
908010 20 30 50 6040 700 100
MAX13301
MAX13301 toc03
EFFICIENCY vs. OUTPUT POWER
PER CHANNEL
100
90
80
70
60
50
40
EFFICIENCY (%)
30
20
10
0
0 90
OUTPUT POWER PER CHANNEL (W)
fIN = 1kHz RL = 4I 10% THD+N BW = 22Hz TO 20kHz AES1
OUTPUT POWER vs. SUPPLY VOLTAGE
100
RL = 4I
90
fIN = 1kHz
80
70
60
50
40
30
20
OUTPUT POWER PER CHANNEL(W)
10
0
10% THD+N
1% THD+N
10 15 20 255 30
V
(V)
PVDD
POWER DISSIPATION vs. OUTPUT POWER
PER CHANNEL
40
35
MAX13301 toc04
30
25
20
15
POWER DISSIPATION (W)
10
5
807050 6020 30 4010
0
OUTPUT POWER PER CHANNEL (W)
RL = 2I f
= 1kHz
IN
10% THD+N BW = 22Hz TO 20kHz AES17
MAX13301 toc05
45405 10 15 25 3020 350 50
CROSSTALK
-40 P
= 4W
OUT
R
= 4I
L
-50
MAX13301 toc07
-60
-70
OUT0 TO OUT2
CROSSTALK (dB)
-80
-90
-100
0.01 100
OUT0 TO OUT3
OUT0 TO OUT1
FREQUENCY (kHz)
1010.1
MAX13301 toc08
POWER DISSIPATION vs. OUTPUT POWER
PER CHANNEL
50
45
40
35
30
25
20
15
POWER DISSIPATION (W)
10
5
0
0 90
OUTPUT POWER PER CHANNEL (W)
fIN = 1kHz RL = 4I 10% THD+N BW = 22Hz TO 20kHz AES17
OUTPUT FREQUENCY SPECTRUM
0
MUTE MODE R
= 4I
L
-20
-40
-60
AMPLITUDE (dBV)
-80
-100
-120 0 20
FREQUENCY (kHz)
MAX13301 toc06
807050 6020 30 4010
MAX13301 toc09
15105
7
4-Channel, Automotive Class D Audio Amplifier
Typical Operating Characteristics (continued)
(V
= 24V, VDD = V
PVDD
TA = +25NC, unless otherwise noted.)
DD5
= 5V, V
GND
= V
= 0V, fSW = 500kHz, MAP.COMP[2:0] = 011, see Table 32 for LC filter value,
PGND
3
2
MAX13301
1
0
RESPONSE (dB)
-1
-2
-3
SPREAD-SPECTRUM MODULATION WIDEBAND
0
-10
-20
-30
-40
-50
AMPLITUDE (dBV)
-60
-70
-80
-90
FREQUENCY RESPONSE
= 1W AND 10W
P
OUT
R
= 4I
L
P
= 30W
OUT
R
= 2I
L
C2 = 1µF
0.01 100 FREQUENCY (kHz)
1010.1
OUTPUT SPECTRUM
CTRL5 = 0x09
MEASURED AT
OUT__ WITH -20dB
ATTENUATION
0.1 100 FREQUENCY (MHz)
101
MAX13301 toc10
MAX13301 toc12
FIXED-FREQUENCY MODULATION WIDEBAND
OUTPUT SPECTRUM
0
-10
-20
-30
-40
-50
AMPLITUDE (dBV)
-60
-70
-80
-90
0.1 100
MEASURED AT OUT__
WITH -20dB ATTENUATION
101
FREQUENCY (MHz)
SPREAD-SPECTRUM MODULATION WIDEBAND
OUTPUT SPECTRUM
0
-10
-20
-30
-40
-50
AMPLITUDE (dBV)
-60
-70
-80
-90
0.1 100
WITH -20dB ATTENUATION
FREQUENCY (MHz)
CTRL5 = 0xB9
MEASURED AT OUT__
101
MAX13301 toc11
MAX13301 toc13
8
4-Channel, Automotive Class D Audio Amplifier
Pin Configuration
TOP VIEW
PVDD
FB2+
FB2-
FB3-
CL0
OUT3+
PGND
PGND
PGND
OUT2+
OUT2-
MUTE_CL1
IN-
GND
V
IN0+
IN1+
REF
PVDD
+
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
DD
19
20
21
22IN2+
23IN3+
24
MAX13301
EPR
48
PVDD
47
CP
46
CHOLD
45
CMFB3+
V
44
DD5
PGND
43
OUT1+
42
OUT1-OUT3-
41
PGND
40
PGNDPGND
39
PGND
38
PGND
37
OUT0+
36
OUT0-
35
FLT_OT
34
FB0+
33
FB0-
32
FB1+
31
FB1-
30
SDA
29
SCL
28
EN
27
SYNC
26
PVDD
25
MAX13301
TSSOP
Pin Description
PIN NAME FUNCTION
Audio Output Power-Supply Input. Bypass each PVDD to its PGND pair locally with 0.1FF and 4.7FF ceramic capacitors. Each PVDD/PGND pair consists of one PVDD and two PGNDs. The PVDD/
1, 24, 25, 48 PVDD
2 FB2+
3 FB2-
PGND pairs are 1 and 9-10, 48 and 39-40, 24 and 11-12, and 25 and 37-38. Bypassing PVDD locally minimizes the area of di/dt loops. An additional 1000FF, low-ESR electrolytic capacitor should be placed from 1 and 48 to PGND and 24 and 25 to PGND.
Output 2 Positive Feedback. Connect to the LC filter’s positive output through a 150I ±1% resistor.
Output 2 Negative Feedback. Connect to the LC filter’s negative output through a 150I ±1% resistor.
9
4-Channel, Automotive Class D Audio Amplifier
Pin Description (continued)
PIN NAME FUNCTION
4 FB3+
5 FB3-
6
MAX13301
7 OUT3+ Channel 3 Power Amplifier Positive Output 8 OUT3- Channel 3 Power Amplifier Negative Output
9–12,
37–40, 43
13 OUT2+ Channel 2 Power Amplifier Positive Output 14 OUT2- Channel 2 Power Amplifier Negative Output
15
16 IN-
17 GND Analog Ground
18 V
19 IN0+
20 IN1+
21 REF
22 IN2+
23 IN3+
26 SYNC
27 EN
28 SCL I2C Serial-Clock Input 29 SDA I2C Serial-Data Input and Output
30 FB1-
31 FB1+
32 FB0-
33 FB0+
CL0
PGND Audio Output Power Ground
MUTE_CL1
DD
Output 3 Positive Feedback. Connect to the LC filter’s positive output through a 150I ±1% resistor.
Output 3 Negative Feedback. Connect to the LC filter’s negative output through a 150I ±1% resistor.
Active-Low Open-Drain Clip 0 Output. CL0 is configurable to provide clipping indication for outputs 0 and 1 or for all four outputs.
Mute Input or Active-Low Open-Drain Clip 1 Output. MUTE_CL1 is configurable as a mute input or as an open-drain clip indicator output. When configured as an input, drive MUTE_CL1 low to mute all four outputs. As an output, MUTE_CL1 provides clipping indication for outputs 2 and 3. This pin also selects the low bit of the I2C address and is latched upon the rising edge of the EN pin. MUTE_CL1 has an internal 5FA pulldown.
Common Audio Negative Input. IN- has 5kI of input resistance. Bypass to analog ground with 2µF or 4 x C
5V Analog Power-Supply Input. Bypass with a 2.2FF or larger ceramic capacitor to GND. V provides power to the analog and digital circuitry.
Channel 0 Audio Input. IN0+ has 20kI of input resistance. Connect a series capacitor of at least
0.47FF to IN0+.
Channel 1 Audio Input. IN1+ has 20kI of input resistance. Connect a series capacitor of at least
0.47FF to IN1+.
2.2V Reference Output. Bypass REF to GND with a 1FF ceramic capacitor.
Channel 2 Audio Input. IN2+ has 20kI of input resistance. Connect a series capacitor of at least
0.47FF to IN2+.
Channel 3 Audio Input. IN3+ has 20kI of input resistance. Connect a series capacitor of at least
0.47FF to IN3+.
Sync I/O. In master mode, SYNC outputs a clock signal that is synchronized to that of the modulator. In slave mode, SYNC is a clock input and serves as the clock source for the modulator.
Enable Input. Connect EN to VDD for normal operation. Connect EN to GND to place the device in a low-power mode. There is an internal 10µA pulldown on EN.
Output 1 Negative Feedback. Connect to the LC filter’s negative output through a 150I ±1% resistor.
Output 1 Positive Feedback. Connect to the LC filter’s positive output through a 150I ±1% resistor.
Output 0 Negative Feedback. Connect to the LC filter’s negative output through a 150I ±1% resistor.
Output 0 Positive Feedback. Connect to the LC filter’s positive output through a 150I ±1% resistor.
IN_+
.
DD
10
4-Channel, Automotive Class D Audio Amplifier
Pin Description (continued)
PIN NAME FUNCTION
34
FLT_OT
35 OUT0- Channel 0 Power Amplifier Negative Output
36 OUT0+ Channel 0 Power Amplifier Positive Output 41 OUT1- Channel 1 Power Amplifier Negative Output 42 OUT1+ Channel 1 Power Amplifier Positive Output
44 V
DD5
45 CM Charge-Pump Capacitor Negative Terminal 46 CHOLD 47 CP Charge-Pump Capacitor Positive Terminal
EPR
Active-Low Open-Drain Fault and Overtemperature Output. FLT_OT provides indication of faults, overtemperature, and thermal shutdown status.
5V Power-Supply Input. Bypass with a 0.1FF capacitor to PGND. V
provides power to the gate
DD5
drivers and charge pump.
Charge-Pump Output. Connect a 1FF capacitor from CHOLD to PVDD.
Top Side Exposed Pad. Connect this exposed pad to an external heatsink to ensure the device is adequately cooled. The maximum power dissipation in the device is a function of this external heatsink and other system parameters. See the Thermal Information section for more information. The top side exposed pad is electrically isolated from the die.
MAX13301
Functional Diagram
V
DD5
PGND
IN_+
IN-
V
GND
REF
SCL
SDA
CLO
MUTE_CL1
FLT_OT
SYNC
OSC
DD
EN
ANALOG
AUDIO
INTERFACE
I2C CONTROL
INTERFACE
REGISTERS
AND
SYSTEM
CONTROL
ANALOG
MODULATOR
AND
DIAGNOSTICS
V
DD5
GATE
DRIVER 0
LPF
LPF
V
DD5
GATE
DRIVER 3
MAX13301
CLASS D
OUTPUT
STAGE 0
AND DIAGS
FEEDBACK DIFF. AMP
FEEDBACK DIFF. AMP
CLASS D
OUTPUT
STAGE 3
AND DIAGS
CHARGE
PUMP
PVDD
OUT0+
OUT0-
PGND
FB0+
FB0-
FB3+
FB3-
PVDD
OUT3+
OUT3-
PGND
CP
CM
CHOLD
11
4-Channel, Automotive Class D Audio Amplifier
2
C COMP
I
MAX13301
AUDIO IN
PWM LOGIC
TRIANGLE WAVE
REF
REF
PWM
COMPARATOR
REF
I2C COMP
ERROR
AMPLIFIER
REF
3-BIT ADC
FEED-
FORWARD
OSC
PVDD
REF
PREAMPLIFIER
Figure 1. Detailed Block Diagram of the MAX13301 Audio Path
Detailed Description
Description of Operation
The device emulates current-mode controllers with digital feed-forward (Figure 1). The internal oscillator creates an 18MHz square wave. The I2C controls a clock divider that divides down this high-frequency clock to a usable fre­quency. The resulting square wave is integrated to create
12
a triangle wave. A 3-bit ADC converts the PVDD voltage into a code that adjusts the resistors used in the triangle­wave integrator. The triangle-wave amplitude becomes progressively larger as PVDD increases. The triangle wave is fed into the PWM comparator.
The two differential amplifiers provide both analog and digital feedback. The feedback is summed with the out­put of the preamplifier at the error amplifier. The output of the error amplifier is an AC replica of the inductor cur­rent (emulated current mode) and the triangle wave is therefore the slope compensation. The PWM comparator controls the full-bridge operation, turning on and off each FET pair (double-edge modulation). To ensure that the devices switch at the desired frequency, it is important to ensure that the triangle wave is greater than the error-
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