TI TAS5112

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SLES048C − JULY 2003 − REVISED MARCH 2004
TM
FEATURES
D 50 W per Channel (BTL) Into 6 Ω (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-Ω Load
D Self-Protecting Design (Undervoltage,
D
D
Overtemperature and Short Conditions) With
Error Reporting
Internal Gate Drive Supply Voltage Regulator
EMI Compliant When Used With
Recommended System Design
APPLICATIONS
D DVD Receiver
D Home Theatre
D Mini/Micro Component Systems
D Internet Music Appliance
DESCRIPTION
The TAS5112 is a high-performance, integrated stereo
digital amplifier power stage designed to drive 6-Ω
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
TAS5112, safeguarding the device and speakers against
fault conditions that could damage the system.
THD + NOISE vs OUTPUT POWER
THD + NOISE vs FREQUENCY
1
THD+N − Total Harmonic Distortion + Noise − %
THD+N − Total Harmonic Distortion + Noise − %
1
RL = 6 Ω
TC = 75°C
0.1
0.01
100m
1
10
100
PO − Output Power − W
RL = 6 Ω
TC = 75°C
PO = 50 W
0.1
PO = 10 W
PO = 1 W
0.01
0.001
20
100
1k
10k 20k
f − Frequency − Hz
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments
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.
! "#$ %!& %
"! "! '! ! !( ! %% )*&
% "!+ %! !!$* $%! !+ $$ "!!&
Copyright  2004, Texas Instruments Incorporated
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SLES048C − JULY 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.
GENERAL INFORMATION
ABSOLUTE MAXIMUM RATINGS
over operating free-air temperature range unless otherwise noted(1)
Terminal Assignment
DFD PACKAGE
(TOP VIEW)
GND
GND
GREG
OTW
SD_CD
SD_AB
PWM_DP
PWM_DM
RESET_CD
PWM_CM
PWM_CP
DREG_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
UNITS
TAS5112
The TAS5112 is offered in a thermally enhanced 56-pin
TSSOP DFD (thermal pad is on the top), shown as follows.
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(2))
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
GND
GVDD
BST_D
PVDD_D
PVDD_D
OUT_D
OUT_D
GND
GND
OUT_C
OUT_C
PVDD_C
PVDD_C
BST_C
BST_B
PVDD_B
PVDD_B
OUT_B
OUT_B
GND
GND
OUT_A
OUT_A
PVDD_A
PVDD_A
BST_A
GVDD
GND
48 V
OUT_X TO GND (dc voltage)
33.5 V
OUT_X TO GND (spike voltage(2))
48 V
BST_X TO GND (dc voltage)
48 V
BST_X TO GND (spike voltage(2))
GREG TO GND (3)
53 V
14.2 V
PWM_XP, RESET, M1, M2, M3, SD,
OTW
–0.3 V to DVDD + 0.3 V
Maximum operating junction
temperature, TJ
–40°C to 150°C
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.
(3) GREG is treated as an input when the GREG pin is overdriven by
GVDD of 12 V.
ORDERING INFORMATION
TA
PACKAGE
DESCRIPTION
0°C to 70°C
TAS5112DFD
56-pin small TSSOP
(1) For the most current specification and package information, refer to
our Web site at www.ti.com.
PACKAGE DISSIPATION RATINGS
PACKAGE
RθJC
(°C/W)
RθJA
(°C/W)
56-pin DAD TSSOP
1.14
See Note 1
(1) The TAS5112 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, RθJA, a system parameter that characterizes the
thermal treatment, is provided in the Application Information section
of the data sheet. An example and discussion of typical system
RθJA values are provided in the Thermal Information section. This
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.
2
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SLES048C − JULY 2003 − REVISED MARCH 2004
Terminal Functions
TERMINAL
NAME
NO.
FUNCTION(1)
DESCRIPTION
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)
1, 2, 22, 24,
27, 28, 29, 36,
37, 48, 49, 56
P
Power ground
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
GND
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
O
Shutdown signal for half-bridges C and D, active-low
SD_CD
5
(1) I = input, O = Output, P = Power
3
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SLES048C − JULY 2003 − REVISED MARCH 2004
FUNCTIONAL BLOCK DIAGRAM
BST_A
GREG
PVDD_A
Gate
Drive
PWM_AP
PWM
Receiver
OUT_A
Timing
Control
Gate
Drive
GND
Protection A
BST_B
RESET
GREG
PVDD_B
Protection B
Gate
Drive
PWM_BP
PWM
Receiver
OUT_B
Timing
Control
Gate
Drive
To Protection
Blocks
GND
DREG
DREG
GVDD
OTW
GREG
OT
Protection
SD
GREG
GREG
DREG
UVP
DREG_RTN
This diagram shows one channel.
4
GREG
DREG_RTN
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SLES048C − JULY 2003 − REVISED MARCH 2004
RECOMMENDED OPERATING CONDITIONS
DVDD
Digital supply (1)
GVDD
Supply for internal gate drive and logic
regulators
PVDD_x
Half-bridge supply
MIN
TYP
MAX
UNIT
Relative to DGND
3
3.3
3.6
V
Relative to GND
16
29.5
30.5
V
Relative to GND, RL= 6 Ω to 8 Ω
0
29.5
30.5
V
125
_C
TJ
Junction temperature
(1) It is recommended for DVDD to be connected to DREG via a 100-Ω resistor.
0
ELECTRICAL CHARACTERISTICS
PVDD_X = 29.5 V, GVDD = 29.5 V, DVDD connected to DREG via a 100-Ω resistor, RL = 6 Ω, 8X fs = 384 kHz, unless otherwise noted
TYPICAL
SYMBOL
PARAMETER
TEST CONDITIONS
TA=25°C
OVER TEMPERATURE
TA=25°C
TCase=
75°C
TA=40°C
TO 85°C
UNITS
MIN/TYP/
MAX
AC PERFORMANCE, BTL Mode, 1 kHz
Po
THD+N
Output power
Total harmonic distortion
+ noise
RL = 8 Ω, THD = 0.2%,
AES17 filter, 1 kHz
40
W
Typ
RL = 8 Ω, THD = 10%, AES17
filter, 1 kHz
50
W
Typ
RL = 6 Ω, THD = 0.2%,
AES17 filter, 1 kHz
50
W
Typ
RL = 6 Ω, THD = 10%, AES17
filter, 1 kHz
62
W
Typ
Po = 1 W/ channel, RL = 6 Ω,
AES17 filter
0.03%
Typ
Po = 10 W/channel, RL = 6 Ω,
AES17 filter
0.04%
Typ
Po = 50 W/channel, RL = 6 Ω,
AES17 filter
0.2%
Typ
Vn
Output integrated voltage
noise
A-weighted, mute, RL = 6 Ω,,
20 Hz to 20 kHz, AES17 filter
260
µV
Max
SNR
Signal-to-noise ratio
A-weighted, AES17 filter
96
dB
Typ
DR
Dynamic range
f = 1 kHz, A-weighted,
AES17 filter
96
dB
Typ
INTERNAL VOLTAGE REGULATOR
DREG
Voltage regulator
Io = 1 mA,
PVDD = 18 V−30.5 V
3.1
V
Typ
GREG
Voltage regulator
Io = 1.2 mA,
PVDD = 18 V−30.5 V
13.4
V
Typ
IVGDD
GVDD supply current,
operating
fS = 384 kHz, no load, 50%
duty cycle
24
mA
Max
IDVDD
DVDD supply current,
operating
fS = 384 kHz, no load
5
mA
Max
1
OUTPUT STAGE MOSFETs
Ron,LS
Forward on-resistance,
low side
TJ = 25°C
155
mΩ
Typ
Ron,HS
Forward on-resistance,
high side
TJ = 25°C
155
mΩ
Typ
5
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SLES048C − JULY 2003 − REVISED MARCH 2004
ELECTRICAL CHARACTERISTICS
PVDD_x = 29.5 V, GVDD = 29.5 V, DVDD connected to DREG via a 100-Ω resistor, RL = 6 Ω, 8X fs = 384 kHz, unless otherwise noted
TYPICAL
SYMBOL
PARAMETER
TEST CONDITIONS
TA=25°C
OVER TEMPERATURE
TCase=
75°C
TA=40°C
TO 85°C
UNITS
MIN/TYP/
MAX
6.9
V
Min
7.9
V
Max
TA=25°C
INPUT/OUTPUT PROTECTION
Vuvp,G
Undervoltage protection
limit, GVDD
Set the DUT in normal
operation mode with all the
protections enabled. Sweep
GVDD up and down. Monitor
SD output. Record the
GREG reading when SD is
triggered.
7.4
OTW
Overtemperature warning,
junction temperature
125
°C
Typ
OTE
Overtemperature error,
junction temperature
150
°C
Typ
OC
Overcurrent protection
5.8
A
Typ
2
V
Min
DVDD
V
Max
0.8
V
Max
−10
µA
Min
10
µA
Max
22.5
kΩ
Min
See Note 1.
STATIC DIGITAL SPECIFICATION
PWM_AP, PWM_BP, M1,
M2, M3, SD, OTW
VIH
High-level input voltage
VIL
Low-level input voltage
Leakage
Input leakage current
OTW/SHUTDOWN (SD)
Internally pull up R from
OTW/SD to DVDD
30
VOL
Low-level output voltage
IO = 4 mA
0.4
V
Max
(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 TAS5112. It is recommended to follow
the TAS5112F2EVM (S/N 112) design and layout guidelines for best performance.
6
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SLES048C − JULY 2003 − REVISED MARCH 2004
SYSTEM CONFIGURATION USED FOR CHARACTERIZATION
Gate-Drive
Power Supply
External Power Supply
H-Bridge
Power Supply
TAS5112DFD
1
1 µF
2
3
4
5
6
ERR_RCVY
7
PWM_AP_1
8
PWM_AM_1
9
VALID_1
10
11
12
100 nF
PWM PROCESSOR
TAS5026
13
14
15
16
17
PWM_AP_2
18
PWM_AM_2
19
VALID_2
20
21
100 Ω
22
23
100 nF
24
25
26
1 µF
27
28
GND
GND
GREG
GND
GVDD
BST_D
OTW
PVDD_D
SD_CD
PVDD_D
SD_AB
OUT_D
PWM_DP
OUT_D
PWM_DM
GND
RESET_CD
GND
PWM_CM
PWM_CP
OUT_C
OUT_C
DREG_RTN
PVDD_C
M3
PVDD_C
M2
BST_C
M1
DREG
BST_B
PVDD_B
PWM_BP
PVDD_B
PWM_BM
OUT_B
RESET_AB
OUT_B
PWM_AM
GND
PWM_AP
GND
GND
DGND
GND
OUT_A
OUT_A
PVDD_A
DVDD
PVDD_A
GREG
BST_A
GND
GVDD
GND
GND
56
55
54 1.5 Ω
53
100 nF
LPCB
33 nF
52
100 nF
51
50
49
10 µH
1.5 Ω
{
4.7 kΩ
470 nF 100 nF
48
47
1.5 Ω
46
{
45
10 µH
100 nF 4.7 kΩ
100 nF
44
LPCB
33 nF
43
1000 µF
42 1.5 Ω
41
LPCB
33 nF
40
100 nF
39
38
37
10 µH
1.5 Ω
{
4.7 kΩ
470 nF 100 nF
36
35
1.5 Ω
34
{
33
10 µH
100 nF 4.7 kΩ
100 nF
32
31
33 nF
LPCB
1000 µF
30 1.5 Ω
29
100 nF
LPCB : TRACK IN THE PCB (1,0 mm wide and 50 mm long)
{Voltage Suppressor Diode: 1SMA33CAT
7
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SLES048C − JULY 2003 − REVISED MARCH 2004
TYPICAL CHARACTERISTICS AND SYSTEM PERFORMANCE
OF TAS5112 EVM WITH TAS5026 PWM PROCESSOR
TOTAL HARMONIC DISTORTION + NOISE
vs
FREQUENCY
NOISE AMPLITUDE
vs
FREQUENCY
0
RL = 6 Ω
TC = 75°C
RL = 6 Ω
FFT = −60 dB
TC = 75°C
TAS5026 Front End Device
−20
PO = 50 W
−40
Noise Amplitude − dBr
THD+N − Total Harmonic Distortion + Noise − %
1
0.1
PO = 10 W
PO = 1 W
0.01
−60
−80
−100
−120
−140
0.001
20
−160
100
1k
0
10k 20k
2
4
6
f − Frequency − Hz
Figure 1
12
14
16
18
20
22
OUTPUT POWER
vs
H-BRIDGE VOLTAGE
10
60
RL = 6 Ω
TC = 75°C
TA = 75°C
50
PO − Output Power − W
THD+N − Total Harmonic Distortion + Noise − %
10
Figure 2
TOTAL HARMONIC DISTORTION + NOISE
vs
OUTPUT POWER
1
0.1
40
RL = 6 Ω
30
RL = 8 Ω
20
10
0.01
100m
0
1
10
PO − Output Power − W
Figure 3
8
8
f − Frequency − kHz
100
0
4
8
12
16
20
24
VDD − Supply Voltage − V
Figure 4
28
32
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SLES048C − JULY 2003 − REVISED MARCH 2004
POWER LOSS
vs
OUTPUT POWER
100
11
90
10
80
9
Ptot − Power Loss − W
η − System Output Stage Efficiency − %
SYSTEM OUTPUT STAGE EFFICIENCY
vs
OUTPUT POWER
70
60
50
40
30
20
8
7
6
5
4
3
2
f = 1 kHz
RL = 6 Ω
TC = 75°C
10
f = 1 kHz
RL = 6 Ω
TC = 75°C
1
0
0
0
5
10 15 20 25 30 35 40 45 50 55 60 65
0
PO − Output Power − W
5
10 15 20 25 30 35 40 45 50 55 60 65
PO − Output Power − W
Figure 5
Figure 6
OUTPUT POWER
vs
CASE TEMPERATURE
AMPLITUDE
vs
FREQUENCY
60
3.0
PVDD = 29.5 V
RL = 6 Ω
58
2.5
2.0
1.5
54
Amplitude − dBr
PO − Output Power − W
56
52
50
Channel 1
48
Channel 2
46
1.0
RL = 6 Ω
0.5
0.0
−0.5
−1.0
RL = 8 Ω
−1.5
44
−2.0
42
−2.5
40
0
20
40
60
80
100
TC − Case Temperature − °C
Figure 7
120
140
−3.0
10
100
1k
10k
50k
f − Frequency − Hz
Figure 8
9
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SLES048C − JULY 2003 − REVISED MARCH 2004
ON-STATE RESISTANCE
vs
JUNCTION TEMPERATURE
200
ron − On-State Resistance − mΩ
190
180
170
160
150
140
130
120
0
10
20
30
40
50
60
70
80
TJ − Junction Temperature − °C
Figure 9
10
90 100
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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. Two 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 topologyand layout-wise. For topology recommendations, see the
Typical System Configuration section. Following these
recommendations is important for parameters like EMI,
reliability, and performance.
POWERING UP
> 1 ms
> 1 ms
RESET
GVDD
This precharges the bootstrap supply capacitors and
discharges the output filter capacitor (see the Typical
TAS5112 Application Configuration section).
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.
PRECAUTION
The TAS5112 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:
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. To comply with the click and pop scheme and
use of non-TI modulators it is recommended to use a 4-kΩ
pulldown resistor on each PWM output node to ground.
C = 33 nF, R = 4.7 kΩ
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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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.
The device can be recovered by toggling RESET low and
then high, after all errors are cleared.
Overcurrent (OC) Protection
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:
DESCRIPTION
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.
SD
RESET
0
0
Not used
0
1
Device in protection mode, i.e., UVP and/or OC
and/or OT error
Undervoltage (UV) Protection
1(1)
0
Device set high-impedance (Hi-Z), SD forced high
1
1
Normal operation
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.
(1) 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.
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.
OTW
DESCRIPTION
0
Junction temperature higher than 125°C
1
Junction temperature lower than 125°C
Reset Function
The function of the reset input is twofold:
D
Reset is used for re-enabling operation after a
latching error event.
D
Reset is used for disabling output stage
switching (mute function).
Overall Reporting
The SD pin, together with the OTW pin, gives chip state
information as described in Table 1.
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 TAS5112 protection function is implemented in a
closed loop with, for example, a system controller and TI
PWM processor. The TAS5112 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 TAS5112 is
self-supported in 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 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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SLES048C − JULY 2003 − REVISED MARCH 2004
Timing and Function
Table 3. Output Mode Selection
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
M3
OUTPUT MODE
0
Bridge-tied load output stage (BTL)
1
Reserved
APPLICATION INFORMATION
DEMODULATION FILTER DESIGN
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(DMOSon), and the power dissipated in the device,
thereby 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.
Shutdown
SD
Autorecovery
PWM
TAS51xx
Counter
Output A
L
AR-RESET
R(Load)
C1A
Figure 10. Autorecovery Function
C2
Latching Shutdown on All Errors (PMODE1)
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
0
0
Autorecovery after errors (PMODE 0)
PROTECTION MODE
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.
C1B
Output B
L
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
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 TAS5112 does not have
distortion issues due to the output inductors and
overcurrent conditions do not occur due to inductor
saturation in the output filter.
13
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SLES048C − JULY 2003 − REVISED MARCH 2004
Another parameter 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 TAS5112.
INDUCTANCE
vs
CURRENT
11
DFB1310A
RθJA is a system thermal resistance from junction to
ambient air. As such, it is a system parameter with roughly
the following components:
D
RθJC (the thermal resistance from junction to
case, or in this case the metal pad)
D
D
Thermal grease thermal resistance
Heatsink thermal resistance
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:
9
L − Inductance − µH
The thermally augmented package provided with the
TAS5112 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 of the
TAS5112, heatsinks can be smaller than those required for
linear amplifiers of equivalent performance.
RθJC has been provided in the General Information
section.
10
DASL983XX−1023
8
7
56-pin HTSSOP
6
0.045 in2
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:
5
56-pin HTSSOP
4
0
5
10
15
I − Current − A
Figure 12. Inductance Saturation
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.
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.
14
THERMAL INFORMATION
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.
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 RθJA = RθJC +
thermal-grease resistance + heatsink resistance.
Table 4, Table 5, and Table 6 indicate modeled
parameters for one or two TAS5112 ICs on a single
heatsink. The final junction temperature is set at 110°C in
www.ti.com
SLES048C − JULY 2003 − REVISED MARCH 2004
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) (1)
56-Pin HTSSOP
Table 6. Case 2A (2 × 60 W Unclipped Into 6 Ω,
Channels in Separate IC Packages) (1)
56-Pin HTSSOP
Ambient temperature
25°C
Power to load (per channel)
60 W (10% THD)
Power dissipation per channel
5.4 W
Delta T inside package
6.1°C, note 2 ×
channel dissipation
Delta T through thermal grease
22.3°C, note 2 ×
channel dissipation
Required heatsink thermal resistance
5.3°C/W
Junction temperature
110°C
Ambient temperature
25°C
System RθJA
15.9°C/W
Power to load (per channel)
50 W (unclipped)
4.5 W
RθJA * power dissipation
Junction temperature
85°C
Power dissipation
Delta T inside package
10.2°C, note 2 ×
channel dissipation
Delta T through thermal grease
37.1°C, note 2 ×
channel dissipation
Required heatsink thermal resistance
4.2°C/W
Junction temperature
110°C
System RθJA
19°C/W
RθJA * power dissipation
Junction temperature
85°C
85°C + 25°C = 110°C
(1) 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.
85°C + 25°C = 110°C
(1) 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.
Table 5. Case 2 (2 × 50 W Unclipped Into 6 Ω,
Channels in Separate Packages) (1)
56-Pin HTSSOP
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 RθJA
19°C/W
RθJA * power dissipation
Junction temperature
85°C
Thermal
Pad
8,20 mm
7,20 mm
85°C + 25°C = 110°C
(1) 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.
3,90 mm
2,98 mm
15
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SLES048C − JULY 2003 − REVISED MARCH 2004
CLICK AND POP REDUCTION
REFERENCES
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 TAS5112 back end:
D
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.
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 Typical System
Configuration).
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.
STATE
Normal(1)
→ Mute
Yes
Mute
→ Normal(1)
Yes
Normal(1)
→
Error recovery
Normal(1)
Error recovery
(ERRCVY)
→ Normal(1)
→ Hard Reset
→ Normal(1)
Hard Reset
(1) Normal = switching
16
CLICK AND
POP REDUCED
Yes
Yes
No
Yes
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
Processor data manual—TI (SLES041)
PWM
6.
TAS5036A Six-Channel Digital Audio
Processor data manual—TI (SLES061)
PWM
7.
TAS3103 Digital Audio Processor With 3D Effects
data manual—TI (SLES038)
8.
Digital Audio Measurements application report—TI
(SLAA114)
9.
PowerPAD Thermally Enhanced
technical brief—TI (SLMA002)
Package
10. System Design Considerations for True Digital
Audio Power Amplifiers application report—TI
(SLAA117)
www.ti.com
SLES048C − JULY 2003 − REVISED MARCH 2004
MECHANICAL DATA
17
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