TEXAS INSTRUMENTS TAS5112A Technical data

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments
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SLES094A - OCTOBER 2003 - REVISED MARCH 2004
   
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TM
FEATURES
D 50 W per Channel (BTL) Into 6 (Stereo) D 95-dB Dynamic Range With TAS5026 D Less Than 0.1% THD+N (1 W RMS Into 6 Ω) D Less Than 0.2% THD+N (50 W RMS into 6 Ω) D Power Efficiency Typically 90% Into 6- Load D Self-Protecting Design (Undervoltage,
Overtemperature and Short Conditions) With Error Reporting
D Internal Gate Drive Supply Voltage Regulator D EMI Compliant When Used With
Recommended System Design
1
THD + NOISE vs OUTPUT POWER
RL = 6 TC = 75°C
APPLICATIONS
D DVD Receiver D Home Theatre D Mini/Micro Component Systems D Internet Music Appliance
DESCRIPTION
The TAS5112A is a high-performance, integrated stereo digital amplifier power stage designed to drive 6- speakers at up to 50 W per channel. The device incorporates TI’s PurePath Digitalt technology and is used with a digital audio PWM processor (TAS50XX) and a simple passive demodulation filter to deliver high-quality, high-efficiency, true-digital audio amplification.
The efficiency of this digital amplifier is typically 90%, reducing the size of both the power supplies and heatsinks needed. Overcurrent protection, overtemperature protection, and undervoltage protection are built into the TAS5112A, safeguarding the device and speakers against fault conditions that could damage the system.
1
THD + NOISE vs FREQUENCY
RL = 6 TC = 75°C
PO = 50 W
0.1
0.1
0.01
THD+N - Total Harmonic Distortion + Noise - %
0.01 100m
semiconductor products and disclaimers thereto appears at the end of this data sheet.
PurePath Digital and PowerPAD are trademarks of Texas Instruments. Other trademarks are the property of their respective owners.
    !   "#$ %!& %   "! "! '! !  !( ! %% )*& % "!+ %!  !!$* $%! !+  $$ "!!&
1 10 100
PO - Output Power - W
THD+N - Total Harmonic Distortion + Noise - %
0.001
PO = 10 W
PO = 1 W
20 100 1k 10k
f - Frequency - Hz
Copyright 2004, Texas Instruments Incorporated
20k
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R
D
D D
C C
B B
A A
DFD PACKAGE
SLES094A - OCTOBER 2003 - REVISED MARCH 2004
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates.
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GENERAL INFORMATION
Terminal Assignment
The TAS5112A is offered in a thermally enhanced 56-pin TSSOP DFD (thermal pad is on the top), shown as follows.
(TOP VIEW)
GND GVDD BST_D PVDD_ PVDD_ OUT_D OUT_D GND GND OUT_C OUT_C PVDD_ PVDD_ BST_C BST_B PVDD_ PVDD_ OUT_B OUT_B GND GND OUT_A OUT_A PVDD_ PVDD_ BST_A GVDD GND
GND GND
GREG
OTW
SD_CD
SD_AB
PWM_DP
PWM_DM
ESET_CD
PWM_CM
PWM_CP
REG_RTN
M3 M2 M1
DREG
PWM_BP
PWM_BM
RESET_AB
PWM_AM
PWM_AP
GND
DGND
GND
DVDD
GREG
GND GND
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29
Absolute Maximum Ratings
over operating free-air temperature range unless otherwise noted
TAS5112A UNITS
DVDD TO DGND –0.3 V to 4.2 V GVDD TO GND 33.5 V PVDD_X TO GND (dc voltage) 33.5 V PVDD_X TO GND (spike voltage OUT_X TO GND (dc voltage) 33.5 V OUT_X TO GND (spike voltage BST_X TO GND (dc voltage) 48 V BST_X TO GND (spike voltage GREG TO GND PWM_XP, RESET, M1, M2, M3, SD,
OTW Maximum operating junction
temperature, T Storage temperature –40°C to 125°C
(1)
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 under “recommended operating conditions” is not implied. Exposure to absolute­maximum-rated conditions for extended periods may affect device reliability.
(2)
The duration of voltage spike should be less than 100 ns; see application note SLEA025.
(3)
GREG is treated as an input when the GREG pin is overdriven by GVDD of 12 V .
(3)
J
(2)
) 48 V
(2)
) 48 V
(2)
) 53 V
–0.3 V to DVDD + 0.3 V
–40°C to 150°C
14.2 V
(1)
Package Dissipation Ratings
R
PACKAGE
56-pin DFD TSSOP 1.14 See Note 4
(4)
The TAS5112A package is thermally enhanced for conductive cooling using an exposed metal pad area. It is impractical to use the device with the pad exposed to ambient air as the only heat sinking of the device. For this reason, R thermal treatment, is provided in the Application Information section of the data sheet. An example and discussion of typical system R
values are provided in the Thermal Information section. This
θJA
example provides additional information regarding the power dissipation ratings. This example should be used as a reference to calculate the heat dissipation ratings for a specific application. TI application engineering provides technical support to design heatsinks if needed.
a system parameter that characterizes the
θJA,
θJC
(°C/W)
R
θJA
(°C/W)
Ordering Information
T
A
0°C to 70°C TAS5112ADFD 56-pin small TSSOP
PACKAGE DESCRIPTION
For the most current specification and package information, refer to our W eb site at www.ti.com.
2
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FUNCTION
(1)
DESCRIPTION
SLES094A - OCTOBER 2003 - REVISED MARCH 2004
Terminal Functions
TERMINAL
NAME NO.
BST_A 31 P High-side bootstrap supply (BST), external capacitor to OUT_A required BST_B 42 P High-side bootstrap supply (BST), external capacitor to OUT_B required BST_C 43 P HS bootstrap supply (BST), external capacitor to OUT_C required BST_D 54 P HS bootstrap supply (BST), external capacitor to OUT_D required DGND 23 P Digital I/O reference ground DREG 16 P Digital supply voltage regulator decoupling pin, capacitor connected to GND DREG_RTN 12 P Digital supply voltage regulator decoupling return pin DVDD 25 P I/O reference supply input (3.3 V) GND 1, 2, 22, 24,
27, 28, 29, 36,
37, 48, 49, 56 GREG 3, 26 P Gate drive voltage regulator decoupling pin, capacitor to REG_GND GVDD 30, 55 P Voltage supply to on-chip gate drive and digital supply voltage regulators M1 (TST0) 15 I Mode selection pin M2 14 I Mode selection pin M3 13 I Mode selection pin OTW 4 O Overtemperature warning output, open drain with internal pullup resistor OUT_A 34, 35 O Output, half-bridge A OUT_B 38, 39 O Output, half-bridge B OUT_C 46, 47 O Output, half-bridge C OUT_D 50, 51 O Output, half-bridge D PVDD_A 32, 33 P Power supply input for half-bridge A PVDD_B 40, 41 P Power supply input for half-bridge B PVDD_C 44, 45 P Power supply input for half-bridge C PVDD_D 52, 53 P Power supply input for half-bridge D PWM_AM 20 I Input signal (negative), half-bridge A PWM_AP 21 I Input signal (positive), half-bridge A PWM_BM 18 I Input signal (negative), half-bridge B PWM_BP 17 I Input signal (positive), half-bridge B PWM_CM 10 I Input signal (negative), half-bridge C PWM_CP 11 I Input signal (positive), half-bridge C PWM_DM 8 I Input signal (negative), half-bridge D PWM_DP 7 I Input signal (positive), half-bridge D RESET_AB 19 I Reset signal, active low RESET_CD 9 I Reset signal, active low SD_AB 6 O Shutdown signal for half-bridges A and B, active-low SD_CD 5 O Shutdown signal for half-bridges C and D, active-low
(1)
I = input, O = Output, P = Power
P Power ground
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3
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SLES094A - OCTOBER 2003 - REVISED MARCH 2004
FUNCTIONAL BLOCK DIAGRAM
PWM_AP
RESET
PWM
Receiver
Protection A
Protection B
GREG
Timing
Control
GREG
Gate
Drive
Gate
Drive
Gate
Drive
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BST_A
PVDD_A
OUT_A
GND
BST_B
PVDD_B
PWM_BP
OTW
SD
PWM
Receiver
To Protection
Blocks
OT
Protection
UVP
This diagram shows one channel.
Control
GREG
Timing
DREG
DREG
Gate
Drive
GREG
DREG_RTN
OUT_B
GND
DREG
GVDD
GREG
GREG
DREG_RTN
4
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Po
Output power
+ noise
SLES094A - OCTOBER 2003 - REVISED MARCH 2004

RECOMMENDED OPERATING CONDITIONS
MIN TYP MAX UNIT
DVDD Digital supply GVDD PVDD_x Half-bridge supply Relative to GND, RL= 6 to 8 0 29.5 30.5 V
T
J
(1)
It is recommended for DVDD to be connected to DREG via a 100- resistor.
Supply for internal gate drive and logic regulators
Junction temperature 0 125 _C
(1)
Relative to DGND 3 3.3 3.6 V Relative to GND 16 29.5 30.5 V
ELECTRICAL CHARACTERISTICS
PVDD_X = 29.5 V, GVDD = 29.5 V, DVDD connected to DREG via a 100- resistor, RL = 6 , 8X fs = 384 kHz, unless otherwise noted
TYPICAL OVER TEMPERATURE
SYMBOL PARAMETER TEST CONDITIONS
AC PERFORMANCE, BTL Mode, 1 kHz
RL = 8 , THD = 0.2%, AES17 filter, 1 kHz
RL = 8 , THD = 10%, AES17 filter, 1 kHz
RL = 6 , THD = 0.2%, AES17 filter, 1 kHz
RL = 6 , THD = 10%, AES17 filter, 1 kHz
Po = 1 W/ channel, RL = 6 Ω, AES17 filter
THD+N
V
n
SNR Signal-to-noise ratio A-weighted, AES17 filter 96 dB Typ DR Dynamic range
INTERNAL VOLTAGE REGULATOR
DREG Voltage regulator
GREG Voltage regulator
IVGDD
IDVDD
OUTPUT STAGE MOSFETs
R
DSon,LS
R
DSon ,HS
Total harmonic distortion + noise
Output integrated voltage noise
GVDD supply current, operating
DVDD supply current, operating
Forward on-resistance, low side
Forward on-resistance, high side
Po = 10 W/channel, RL = 6 Ω, AES17 filter
Po = 50 W/channel, RL = 6 Ω, AES17 filter
A-weighted, mute, RL = 6 Ω,, 20 Hz to 20 kHz, AES17 filter
f = 1 kHz, A-weighted, AES17 filter
Io = 1 mA, PVDD = 18 V-30.5 V
Io = 1.2 mA, PVDD = 18 V-30.5 V
fS = 384 kHz, no load, 50% duty cycle
fS = 384 kHz, no load 1 5 mA Max
TJ = 25°C 155 mΩ Typ
TJ = 25°C 155 mΩ Typ
TA=25°C TA=25°C
3.1 V Typ
13.4 V Typ
24 mA Max
T
=
Case
75°C
0.03% Typ
0.04% Typ
0.2% Typ
260 µV Max
TA=40°C
TO 85°C
40 W Typ
50 W Typ
50 W Typ
62 W Typ
96 dB Typ
UNITS
MIN/TYP/
MAX
5

Undervoltage protection
V
Undervoltage protection GVDD up and down. Monitor
7.4
VIHHigh-level input voltage
Leakage
Input leakage current
SLES094A - OCTOBER 2003 - REVISED MARCH 2004
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ELECTRICAL CHARACTERISTICS
PVDD_x = 29.5 V, GVDD = 29.5 V, DVDD connected to DREG via a 100- resistor, RL = 6 , 8X fs = 384 kHz, unless otherwise noted
TYPICAL OVER TEMPERATURE
SYMBOL PARAMETER TEST CONDITIONS
INPUT/OUTPUT PROTECTION
Set the DUT in normal operation mode with all the protections enabled. Sweep
uvp,G
OTW
OTE OC Overcurrent protection See Note 1. 6.7 A Typ
STATIC DIGITAL SPECIFICATION
V
IL
OTW/SHUTDOWN (SD)
V
OL
(1)
To optimize device performance and prevent overcurrent (OC) protection tripping, the demodulation filter must be designed with special care. See Demodulation Filter Design in the Application Information section of the data sheet and consider the recommended inductors and capacitors for optimal performance. It is also important to consider PCB design and layout for optimum performance of the TAS5112A. It is recommended to follow the TAS5112F2EVM (S/N 112) design and layout guidelines for best performance.
limit, GVDD
Overtemperature warning, junction temperature
Overtemperature error, junction temperature
PWM_AP, PWM_BP, M1, M2, M3, SD, OTW
Low-level input voltage 0.8 V Max
Internally pull up R from OTW/SD to DVDD
Low-level output voltage IO = 4 mA 0.4 V Max
SD output. Record the GREG reading when SD is triggered.
TA=25°C TA=25°C
6.9 V Min
7.9 V Max
125 °C Typ
150 °C Typ
DVDD V Max
-10 µA Min 10 µA Max
30 22.5 k Min
T
=
Case
75°C
2 V Min
TA=40°C
TO 85°C
UNITS
MIN/TYP/
MAX
6
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Gate-Drive
PCB
SYSTEM CONFIGURATION USED FOR CHARACTERIZATION
Power Supply
External Power Supply
H-Bridge
Power Supply
TAS5112ADFD
ERR_RCVY PWM_AP_1
PWM_AM_1
VALID_1
PWM PROCESSOR
TAS5026
PWM_AP_2
PWM_AM_2
VALID_2
1 µF
100 nF
100
100 nF
1 µF
1
GND
2
GND
3
GREG
4
OTW
5
SD_CD
6
SD_AB
7
PWM_DP
8
PWM_DM
9
RESET_CD
10
PWM_CM
11
PWM_CP
12
DREG_RTN
13
M3
14
M2
15
M1
16
DREG
17
PWM_BP
18
PWM_BM
19
RESET_AB
20
PWM_AM
21
PWM_AP
22
GND
23
DGND
24
GND
25
DVDD
26
GREG
27
GND
28
GND
BST_D PVDD_D PVDD_D
OUT_D OUT_D
OUT_C
OUT_C PVDD_C PVDD_C
BST_C
BST_B PVDD_B PVDD_B
OUT_B OUT_B
OUT_A
OUT_A PVDD_A PVDD_A
BST_A
GND
GVDD
GND GND
GND GND
GVDD
GND
56 55
1.5
54 53 52 51 50 49 48 47 46 45 44 43
1.5
42 41 40 39 38 37 36 35 34 33 32 31
1.5
30 29
33 nF
100 nF
1.5
1.5
33 nF
33 nF
100 nF
1.5
1.5
33 nF

SLES094A - OCTOBER 2003 - REVISED MARCH 2004
100 nF
L
PCB
10 µH
10 µH
100 nF
L
PCB
L
PCB
10 µH
10 µH
100 nF
L
PCB
470 nF
470 nF
100 nF
100 nF
100 nF
100 nF
100 nF
4.7 k
4.7 k
4.7 k
4.7 k
1000 µF
1000 µF
Voltage suppressor diodes: 1SMA33CAT
L
: Track in the PCB (1,0 mm wide and 50 mm long)
7
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THD+N - Total Harmonic Distortion + Noise - %
THD+N - Total Harmonic Distortion + Noise - %
SLES094A - OCTOBER 2003 - REVISED MARCH 2004
TYPICAL CHARACTERISTICS AND SYSTEM PERFORMANCE
OF TAS5112A EVM WITH TAS5026 PWM PROCESSOR
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TOTAL HARMONIC DISTORTION + NOISE
vs
FREQUENCY
1
RL = 6 TC = 75°C
PO = 50 W
0.1
PO = 10 W
PO = 1 W
0.01
0.001 20 100 1k 10k
f - Frequency - Hz
Figure 1
20k
NOISE AMPLITUDE
vs
FREQUENCY
0
RL = 6 FFT = -60 dB
−20 TC = 75°C
TAS5026 Front End Device
−40
−60
−80
−100
Noise Amplitude - dBr
−120
−140
−160 0 2 4 6 8 10121416182022
f - Frequency - kHz
Figure 2
TOTAL HARMONIC DISTORTION + NOISE
10
RL = 6 TC = 75°C
1
0.1
0.01 100m
8
vs
OUTPUT POWER
1 10 100
PO - Output Power - W
Figure 3
OUTPUT POWER
vs
H-BRIDGE VOLTAGE
60
TA = 75°C
50
40
RL = 6
30
- Output Power - W
20
O
P
10
0
0 4 8 12 16 20 24 28 32
VDD - Supply Voltage - V
Figure 4
RL = 8
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- System Output Stage Efficiency - %
P
- Output Power - W
k
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SLES094A - OCTOBER 2003 - REVISED MARCH 2004
SYSTEM OUTPUT STAGE EFFICIENCY
vs
OUTPUT POWER
100
90
80 70
60 50
40 30
20
η
10
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65
PO - Output Power - W
Figure 5
f = 1 kHz RL = 6 TC = 75°C
POWER LOSS
vs
OUTPUT POWER
11
f = 1 kHz
10
RL = 6
9
TC = 75°C 8 7 6 5
- Power Loss - W
4
tot
P
3 2 1 0
0 5 10 15 20 25 30 35 40 45 50 55 60 65
PO - Output Power - W
Figure 6
OUTPUT POWER
vs
CASE TEMPERATURE
60
PVDD = 29.5 V
58
RL = 6
56 54
52 50
48
O
46
44 42 40
0 20 40 60 80 100 120 140
TC - Case Temperature - °C
Channel 2
Figure 7
Channel 1
AMPLITUDE
vs
FREQUENCY
3.0
2.5
2.0
1.5
1.0
0.5
0.0
−0.5
Amplitude - dBr
−1.0
−1.5
−2.0
−2.5
−3.0 10 100 1k 50
f - Frequency - Hz
RL = 8
Figure 8
RL = 6
10k
9
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SLES094A - OCTOBER 2003 - REVISED MARCH 2004
200
190
180
170
160
150
- On-State Resistance - m
140
on
r
130
120
0 102030405060708090100
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ON-STATE RESISTANCE
vs
JUNCTION TEMPERATURE
TJ - Junction Temperature - °C
Figure 9
10
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SLES094A - OCTOBER 2003 - REVISED MARCH 2004
THEORY OF OPERATION
POWER SUPPLIES
The power device only requires two supply voltages, GVDD and PVDD_X.
GVDD is the gate drive supply for the device, regulated internally down to approximately 12 V, and decoupled with regards to board GND on the GREG pins through an external capacitor. GREG powers both the low side and high side via a bootstrap step-up conversion. The bootstrap supply is charged after the first low-side turn-on pulse. Internal digital core voltage DREG is also derived from GVDD and regulated down by internal circuitry to
3.3 V. The gate-driver regulator can be bypassed for reducing
idle loss in the device by shorting GREG to GVDD and directly feeding in 12.0 V. This can be useful in an application where thermal conduction of heat from the device is difficult.
PVDD_X is the H-bridge power supply pin. T wo power pins exists for each half-bridge to handle the current density . It is important that the circuitry recommendations around the PVDD_X pins are followed carefully both topology- and layout-wise. For topology recommendations, see the System Configuration Used for Characterization section. Following these recommendations is important for parameters like EMI, reliability, and performance.
POWERING UP
4.7-kpulldown resistor on each PWM output node to ground. This precharges the bootstrap supply capacitors and discharges the output filter capacitor.
After GVDD has been applied, it takes approximately 800 µs to fully charge the BST capacitor. Within this time, RESET must be kept low. After approximately 1 ms, the back-end bootstrap capacitor is charged.
RESET can now be released if the modulator is powered up and streaming valid PWM signals to the back-end PWM_xP. Valid means a switching PWM signal which complies with the frequency and duty cycle ranges stated in the Recommended Operating Conditions.
A constant HIGH dc level on the PWM_xP is not permitted, because it would force the high-side MOSFET ON until it eventually ran out of BST capacitor energy and might damage the device.
An unknown state of the PWM output signals from the modulator is illegal and should be avoided, which in practice means that the PWM processor must be powered up and initialized before RESET is de-asserted HIGH to the back end.
POWERING DOWN
For power down of the back end, an opposite approach is necessary. The RESET must be asserted LOW before the valid PWM signal is removed.
When PWM processors are used with TI PurePath Digital amplifiers, the correct timing control of RESET and PWM_xP is performed by the modulator.
> 1 ms
> 1 ms
RESET
GVDD
PVDD_X
PWM_xP
NOTE:
PVDD should not be powered up before GVDD.
During power up when RESET is asserted LOW, all MOSFETs are turned off and the two internal half-bridges are in the high-impedance state (Hi-Z). The bootstrap capacitors supplying high-side gate drive are not charged at this point. T o comply with the click and pop scheme and use of non-TI modulators, it is recommended to use a
PRECAUTION
The TAS5112A must always start up in the high-impedance (Hi-Z) state. In this state, the bootstrap (BST) capacitor is precharged by a resistor on each PWM output node to ground. See the system configuration. This ensures that the back end is ready for receiving PWM pulses, indicating either HIGH- or LOW-side turnon after RESET is de-asserted to the back end.
With the following pulldown resistor and BST capacitor size, the charge time is:
C = 33 nF, R = 4.7 k R × C × 5 = 775.5 µs
After GVDD has been applied, it takes approximately 800 µs to fully charge the BST capacitor. During this time, RESET must be kept low. After approximately 1 ms the back end BST is charged and ready. RESET can now be released if the PWM modulator is ready and is streaming valid PWM signals to the back end. Valid PWM signals are switching PWM signals with a frequency between 350-400 kHz. A constant HIGH level on the PWM+ would force the high-side MOSFET ON until it eventually ran out of BST capacitor energy. Putting the device in this condition should be avoided.
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SLES094A - OCTOBER 2003 - REVISED MARCH 2004
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In practice this means that the DVDD-to-PWM processor (front-end) should be stable and initialization should be completed before RESET is de-asserted to the back end.
CONTROL I/O
Shutdown Pin: SD
The SD pin functions as an output pin and is intended for protection-mode signaling to, for example, a controller or other front-end device. The pin is open-drain with an internal pullup resistor to DVDD.
The logic output is, as shown in the following table, a combination of the device state and RESET input:
SD RESET DESCRIPTION
0 0 Reserved 0 1 Device in protection mode, i.e., UVP and/or OC
and/or OT error
(2)
1
1 1 Normal operation
Temperature Warning Pin: OTW
The OTW pin gives a temperature warning signal when temperature exceeds the set limit. The pin is of the open-drain type with an internal pullup resistor to DVDD.
Overall Reporting
The SD pin, together with the OTW pin, gives chip state information as described in Table 1.
0 Device set high-impedance (Hi-Z), SD forced high
(2)
SD is pulled high when RESET is asserted low independent of chip state (i.e., protection mode). This is desirable to maintain compatibility with some TI PWM front ends.
OTW DESCRIPTION
0 Junction temperature higher than 125°C 1 Junction temperature lower than 125°C
The device can be recovered by toggling RESET low and then high, after all errors are cleared.
Overcurrent (OC) Protection
The device has individual forward current protection on both high-side and low-side power stage FETs. The OC protection works only with the demodulation filter present at the output. See Demodulation Filter Design in the Application Information section of the data sheet for design constraints.
Overtemperature (OT) Protection
A dual temperature protection system asserts a warning signal when the device junction temperature exceeds 125°C. The OT protection circuit is shared by all half-bridges.
Undervoltage (UV) Protection
Undervoltage lockout occurs when GVDD is insufficient for proper device operation. The UV protection system protects the device under power-up and power-down situations. The UV protection circuits are shared by all half-bridges.
Reset Function
The reset has two functions:
D Reset is used for re-enabling operation after a
latching error event.
D Reset is used for disabling output stage
switching (mute function).
The error latch is cleared on the falling edge of reset and normal operation is resumed when reset goes high.
Table 1. Error Signal Decoding
OTW SD DESCRIPTION
0 0 Overtemperature error (OTE) 0 1 Overtemperature warning (OTW) 1 0 Overcurrent (OC) or undervoltage (UVP) error 1 1 Normal operation, no errors/warnings
Chip Protection
The TAS5112A protection function is implemented in a closed loop with, for example, a system controller and TI PWM processor. The TAS5112A contains three individual systems protecting the device against error conditions. All of the error events covered result in the output stage being set in a high-impedance state (Hi-Z) for maximum protection of the device and connected equipment.
12
PROTECTION MODE
Autorecovery (AR) After Errors (PMODE0)
In autorecovery mode (PMODE0) the TAS5112A is self-supported i n handling of error situations. All protection systems are active, setting the output stage in the high-impedance state to protect the output stage and connected equipment. However, after a short time period the device autorecovers, i.e., operation is automatically resumed provided that the system is fully operational.
The autorecovery timing is set by counting PWM input cycles, i.e., the timing is relative to the switching frequency.
The AR system is common to both half-bridges.
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Timing and Function
The function of the autorecovery circuit is as follows:
1. An error event occurs and sets the protection latch (output stage goes Hi-Z).
2. The counter is started.
3. After n/2 cycles, the protection latch is cleared but the output stage remains Hi-Z (identical to pulling RESET
low).
4. After n cycles, operation is resumed (identical to pulling RESET high) (n = 512).
Error
Protection
Latch
Shutdown
SD
Autorecovery
PWM
Counter
R-RESET
Figure 10. Autorecovery Function
Latching Shutdown on All Errors (PMODE1)
Table 3. Output Mode Selection
M3 OUTPUT MODE
0 Bridge-tied load output stage (BTL) 1 Reserved
APPLICATION INFORMATION
DEMODULATION FILTER DESIGN AND SPIKE CONSIDERATIONS
The output square wave is susceptible to overshoots (voltage spikes). The spike characteristics depend on many elements, including silicon design and application design and layout. The device should be able to handle narrow spike pulses, less than 65 ns, up to 65 volts peak. For more detailed information, see TI application note SLEA025.
The PurePath Digital amplifier outputs are driven by heavy-duty DMOS transistors in an H-bridge configuration. These transistors are either off or fully on, which reduces the DMOS transistor on-state resistance, R
, and the power dissipated in the device, thereby
DSon
increasing efficiency. The result is a square-wave output signal with a duty cycle
that is proportional to the amplitude of the audio signal. It is recommended that a second-order LC filter be used to recover the audio signal. For this application, EMI is considered important; therefore, the selected filter is the full-output type shown in Figure 11.
TAS51xx
In latching shutdown mode, all error situations result in a power down (output stage Hi-Z). Re-enabling can be done by toggling the RESET pin.
All Protection Systems Disabled (PMODE2)
In PMODE2, all protection systems are disabled. This mode is purely intended for testing and characterization purposes and thus not recommended for normal device operation.
MODE Pins Selection
The protection mode is selected by shorting M1/M2 to DREG or DGND according to Table 2.
Table 2. Protection Mode Selection
M1 M2 PROTECTION MODE
0 0 Autorecovery after errors (PMODE 0) 0 1 Latching shutdown on all errors (PMODE 1) 1 0 All protection systems disabled (PMODE 2) 1 1 Reserved
The output configuration mode is selected by shorting the M3 pin to DREG or DGND according to Table 3.
Output A
Output B
L
L
C1A
C1B
C2
R
(Load)
Figure 11. Demodulation Filter
The main purpose of the output filter is to attenuate the high-frequency switching component of the PurePath Digital amplifier while preserving the signals in the audio band.
Design of the demodulation filter affects the performance of the power amplifier significantly. As a result, to ensure proper operation of the overcurrent (OC) protection circuit and meet the device THD+N specifications, the selection of the inductors used in the output filter must be considered according to the following. The rule is that the inductance
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L - Inductance -
H
SLES094A - OCTOBER 2003 - REVISED MARCH 2004
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should remain stable within the range of peak current seen at maximum output power and deliver at least 5 µH of inductance at 15 A.
If this rule is observed, the TAS5112A does not have distortion issues due to the output inductors, and overcurrent conditions do not occur due to inductor saturation in the output filter.
Another par a meter to be considered is the idle current loss in the inductor. This can be measured or specified as inductor dissipation (D). The target specification for dissipation is less than 0.05.
In general, 10-µH inductors suffice for most applications. The frequency response of the amplifier is slightly altered by the change in output load resistance; however, unless tight control of frequency response is necessary (better than 0.5 dB), it is not necessary to deviate from 10 µH.
The graphs in Figure 12 display the inductance vs current characteristics of two inductors that are recommended for use with the TAS5112A.
INDUCTANCE
vs
CURRENT
11
In order to minimize the EMI effect of unbalanced ripple loss in the inductors, 0.1-µF 50-V SMD capacitors (X7R or better) (C1A and C1B in Figure 11) should be added from the output of each inductor to ground.
THERMAL INFORMATION
The thermally augmented package provided with the TAS5112A is designed to be interfaced directly to heatsinks using a thermal interface compound (for example, Wakefield Engineering type 126 thermal grease.) The heatsink then absorbs heat from the ICs and couples it to the local air. If the heatsink is carefully designed, this process can reach equilibrium and heat can be continually removed from the ICs. Because of the efficiency o f the TAS5112A, heatsinks can be smaller than those required for linear amplifiers of equivalent performance.
R
is a system thermal resistance from junction to
θ
JA
ambient ai r. As such, it is a system parameter with roughly the following components:
D R
(the thermal resistance from junction to
θ
JC
case, or in this case the metal pad)
D Thermal grease thermal resistance D Heatsink thermal resistance
µ
The selection of the capacitor that is placed across the output of each inductor (C2 in Figure 11) is simple. To complete the output filter, use a 0.47-µF capacitor with a voltage rating at least twice the voltage applied to the output stage (PVDD).
This capacitor should be a good quality polyester dielectric such as a Wima MKS2-047ufd/100/10 or equivalent.
10
DFB1310A
9
DASL983XX-1023
8
7
6
5
4
0 5 10 15
I - Current - A
Figure 12. Inductance Saturation
R
has been provided in the General Information
θ
JC
section. The thermal grease thermal resistance can be calculated
from the exposed pad area and the thermal grease manufacturer’s area thermal resistance (expressed in °C-in2/W). The area thermal resistance of the example thermal grease with a 0.002-inch thick layer is about 0.1 °C-in2/W. The approximate exposed pad area is as follows:
56-pin HTSSOP 0.045 in
2
Dividing the example thermal grease area resistance by the surface area gives the actual resistance through the thermal grease for both ICs inside the package:
56-pin HTSSOP 2.27 °C/W
The thermal resistance of thermal pads is generally considerably higher than a thin thermal grease layer. Thermal tape has an even higher thermal resistance. Neither pads nor tape should be used with either of these two packages. A thin layer of thermal grease with careful clamping of the heatsink is recommended. It may be difficult to achieve a layer 0.001-inch thick or less, so the modeling below is done with a 0.002-inch thick layer, which may be more representative of production thermal grease thickness.
14
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Heatsink thermal resistance is generally predicted by the heatsink vendor, modeled using a continuous flow dynamics (CFD) model, or measured.
Thus, for a single monaural IC, the system R
= R
θ
JA
+
θ
JC
thermal grease resistance + heatsink resistance.
Table 4, Table 5, and Table 6 indicate modeled parameters for one or two TAS5112A ICs on a single heatsink. The final junction temperature is set at 110°C in all cases. It is assumed that the thermal grease is 0.002 inch thick and that it is similar in performance to Wakefield Type 126 thermal grease. It is important that the thermal grease layer is 0.002 inches thick and that thermal pads or tape are not used in the pad-to-heatsink interface due to the high power density that results in these extreme power cases.
Table 4. Case 1 (2 × 50 W Unclipped Into 6 Ω,
Both Channels in Same IC)
Ambient temperature 25°C Power to load (per channel) 50 W (unclipped) Power dissipation 4.5 W
Delta T inside package
Delta T through thermal grease Required heatsink thermal resistance 4.2°C/W
Junction temperature 110°C System R R Junction temperature 85°C + 25°C = 110°C
(1)
θJA
* power dissipation 85°C
θJA
This case represents a stereo system with only one package. See Case 2 and Case 2A if doing a full-power, 2-channel test in a multichannel system.
(1)
56-Pin HTSSOP
10.2°C, note 2 × channel dissipation
37.1°C, note 2 × channel dissipation
19°C/W
Table 5. Case 2 (2 × 50 W Unclipped Into 6 Ω,
Channels in Separate Packages)
Ambient temperature 25°C Power to load (per channel) 50 W (unclipped) Power dissipation 4.5 W Delta T inside package 5.1°C Delta T through thermal grease 18.6°C Required heatsink thermal resistance 6.9°C/W Junction temperature 110°C System R R Junction temperature 85°C + 25°C = 110°C
(1)
θJA
* power dissipation 85°C
θJA
In this case, the power is separated into two packages. Note that this allows a considerably smaller heatsink because twice as much area is available for heat transfer through the thermal grease. For this reason, separating the stereo channels into two ICs is recommended in full-power stereo tests made on multichannel systems.
19°C/W
(1)
56-Pin HTSSOP
Table 6. Case 2A (2 × 60 W Into 6 Ω, Channels in
Separate IC Packages)
Ambient temperature 25°C Power to load (per channel) 60 W (10% THD) Power dissipation per channel 5.4 W
Delta T inside package
Delta T through thermal grease Required heatsink thermal resistance 5.3°C/W
Junction temperature 110°C System R R Junction temperature 85°C + 25°C = 110°C
(1)
θJA
* power dissipation 85°C
θJA
In this case, the power is also separated into two packages, but overdriving causes clipping to 10% THD. In this case, the high power requires extreme care in attachment of the heatsink to ensure that the thermal grease layer is 0.002 inches thick. Note that this power level should not be attempted with both channels in a single IC because of the high power density through the thermal grease layer.
(1)
56-Pin HTSSOP
6.1°C, note 2 × channel dissipation
22.3°C, note 2 × channel dissipation
15.9°C/W
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SLES094A - OCTOBER 2003 - REVISED MARCH 2004
Thermal
Pad
8,20 mm 7,20 mm
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Other things that can affect the audible click level:
D The spectrum of the click seems to follow the
speaker impedance vs. frequency curve—the higher the impedance, the higher the click energy.
D Crossover filters used between woofer and
tweeter in a speaker can have high impedance in the audio band, which should be avoided if possible.
Another way to look at it is that the speaker impulse response is a major contributor to how the click energy is shaped in the audio band and how audible the click will be.
The following mode transitions feature click and pop reduction.
3,90 mm 2,98 mm
CLICK AND POP REDUCTION
TI modulators feature a pop and click reduction system that controls the timing when switching starts and stops.
Going from nonswitching to switching operation causes a spectral energy burst to occur within the audio bandwidth, which is heard in the speaker as an audible click, for instance, after having asserted RESET LH during a system start-up.
To make this system work properly, the following design rules must be followed when using the TAS5112A back end:
D The relative timing between the PWM_AP/M_x
signals and their corresponding VALID_x signal should not be skewed by inserting delays, because this increases the audible amplitude level of the click.
D The output stage must start switching from a
fully discharged output filter capacitor. Because the output stage prior to operation is in the high-impedance state, this is done by having a passive pulldown resistor on each speaker output to GND (see System Configuration Used for Characterization).
STATE
(1)
Normal Mute Normal
(1)
Normal Error recovery → Normal
(1)
Normal Hard Reset → Normal
(1)
Normal = switching
Mute Yes
Error recovery
(ERRCVY)
Hard Reset No
(1)
(1)
(1)
CLICK AND
POP REDUCED
Yes Yes Yes
Yes
REFERENCES
1. TAS5000 Digital Audio PWM Processor data manual—TI (SLAS270)
2. True Digital Audio Amplifier TAS5001 Digital Audio PWM Processor data sheet—TI (SLES009)
3. True Digital Audio Amplifier TAS5010 Digital Audio PWM Processor data sheet—TI (SLAS328)
4. True Digital Audio Amplifier TAS5012 Digital Audio PWM Processor data sheet—TI (SLES006)
5. TAS5026 Six-Channel Digital Audio PWM Processor data manual—TI (SLES041)
6. TAS5036A Six-Channel Digital Audio PWM Processor data manual—TI (SLES061)
7. TAS3103 Digital Audio Processor With 3D Effects data manual—TI (SLES038)
8. Digital Audio Measurements application report—TI (SLAA114)
9. PowerPAD Thermally Enhanced Package technical brief—TI (SLMA002)
10. System Design Considerations for True Digital Audio Power Amplifiers application report—TI (SLAA117)
16
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MECHANICAL DATA
17
PACKAGE OPTION ADDENDUM
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16-May-2005
PACKAGING INFORMATION
Orderable Device Status
(1)
Package
Type
Package Drawing
Pins Package
Qty
Eco Plan
TAS5112ADCA ACTIVE HTSSOP DCA 56 35 Green(RoHS &
no Sb/Br)
TAS5112ADCAG4 ACTIVE HTSSOP DCA 56 35 Green (RoHS &
no Sb/Br)
TAS5112ADCAR ACTIVE HTSSOP DCA 56 2000 Green (RoHS &
no Sb/Br)
TAS5112ADCARG4 ACTIVE HTSSOP DCA 56 2000 Green (RoHS &
no Sb/Br)
TAS5112ADFD ACTIVE HTSSOP DFD 56 35 Green (RoHS &
no Sb/Br)
TAS5112ADFDR ACTIVE HTSSOP DFD 56 2000 Green (RoHS &
no Sb/Br)
TAS5112ADFDRG4 ACTIVE HTSSOP DFD 56 2000 Green (RoHS &
no Sb/Br)
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in
a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device.
(2)
Lead/Ball Finish MSL Peak Temp
CU NIPDAU Level-3-260C-168 HR
CU NIPDAU Level-3-260C-168 HR
CU NIPDAU Level-3-260C-168 HR
CU NIPDAU Level-3-260C-168 HR
CU NIPDAU Level-3-260C-168 HR
CU NIPDAU Level-3-260C-168 HR
CU NIPDAU Level-3-260C-168 HR
(3)
(2)
Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS) or Green (RoHS & no Sb/Br) - please check
http://www.ti.com/productcontent for the latest availability information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements
for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material)
(3)
MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder
temperature.
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Addendum-Page 1
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