ETC TK2070

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TK2070
STEREO 70W (4Ω) CLASS-T™ DIGITAL AUDIO AMPLIFIER
DRIVER USING DIGITAL POWER PROCESSING (DPP™)
TECHNOLOGY
Preliminary Information
Revision 2.1 – October 2003
GENERAL DESCRIPTION
The TK2070 (TC2001/TPS1035 chipset) is a bridged stereo 70W continuous average power per
channel, Class-T Digital Audio Power Amplifier using Tripath’s proprietary Digital Power ProcessingTM
technology. The TK2070 chipset consists of 1 TC2001 and 4 TPS1035’s to obtain a bridged stereo
configuration. Class-T amplifiers offer both the audio fidelity of Class-AB and the power efficiency of
Class-D amplifiers.
APPLICATIONS
5.1-Channel DVD
Mini/Micro Component Systems
Home Theater
Stereo applications (4Ω / 8Ω)
Powered Subwoofer
BENEFITS
Single Supply Operation
Very High Efficiency
Wide Dynamic Range
Compact layout
1
FEATURES
Class-T Architecture
High Output power
70W @ 4Ω, 10% THD+N Bridged
40W @ 8Ω, 10% THD+N Bridged
Audiophile Quality Sound
0.03% THD+N @ 35W 4Ω Bridged
0.03% THD+N @ 25W 8Ω Bridged
High Efficiency
86% @ 70W 4Ω Bridged
92% @ 40W 8Ω Bridged
Dynamic Range >100 dB
TK2070 – MC/2.1/10-03
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A B S O L U T E M A X I M U M R A T I N G S – T C 2 0 0 1 (Note 1)
SYMBOL
V5
PARAMETER
Value
UNITS
6
V
5V Power Supply
Vlogic
Input Logic Level
V5+0.3V
V
TA
Operating Free-air Temperature Range
-40 to 85
°C
TSTORE
Storage Temperature Range
-55 to 150
°C
TJMAX
Maximum Junction Temperature
150
°C
ESDHB
ESD Susceptibility – Human Body Model (Note 2), all pins
2000
V
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur.
See the table below for Operating Conditions.
Note 2: Human body model, 100pF discharged through a 1.5KΩ resistor.
A B S O L U T E M A X I M U M R A T I N G S – T P S 1 0 3 5 (Note 1)
SYMBOL
PARAMETER
Value
UNITS
VDD
Power Supply
26
V
Vlogic
Input Logic Level
5.5
V
TA
Operating Free-air Temperature Range
-40 to 85
°C
TSTORE
Storage Temperature Range
-40 to 150
°C
TJMAX
Maximum Junction Temperature
150
°C
ESDHB
ESD Susceptibility – Human Body Model (Note 2), all pins except 1, 8
Pins 1, 8
2000
400
V
ESDMM
ESD Susceptibility – Machine Model (Note 3), all pins
200
V
Note 3: Machine model, 220pF – 240pF discharged through all pins.
OPERATING CONDITIONS – TC2001
MIN.
TYP.
MAX.
UNITS
V5
SYMBOL
Supply Voltage
PARAMETER
4.5
5
5.5
V
VHI
Logic Input High
V5-1.0
VLO
Logic Input Low
TA
Operating Temperature Range
-40
V
25
1
V
85
°C
OPERATING CONDITIONS – TPS1035
SYMBOL
PARAMETER
VDD
Power Supply
VHI
Logic Input High
MIN.
TYP.
MAX.
UNITS
25
V
8
TBD
VLO
Logic Input Low
TA
Operating Temperature Range
-40
V
TBD
V
85
°C
25
THERMAL CHARACTERISTICS
TC2001
SYMBOL
PARAMETER
Junction-to-ambient Thermal Resistance (still air)
θJA
2
Value
UNITS
80
°C/W
TK2070 – MC/2.1/10-03
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TPS1035
SYMBOL
Value
UNITS
θJA
Junction-to-Ambient Thermal Resistance
PARAMETER
50
°C/W
θJC
Junction-to-case Thermal Resistance
8
°C/W
ELECTRICAL CHARACTERISTICS – TC2001
SYMBOL
PARAMETER
MIN.
TYP.
I5
Supply Current
60
mA
fsw
Switching Frequency (adjustable via CFB)
600
650
kHz
VIN
Input Sensitivity
VOUTHI
High Output Voltage
VOUTLO
Low Output Voltage
RIN
0
MAX.
1.5
V
100
mV
V5-0.5
Input Impedance
Input DC Bias
UNITS
V
2
kΩ
2.5
V
ELECTRICAL CHARACTERISTICS – TK2070
TA = 25 °C. See Application/Test Circuit. Unless otherwise noted, the supply voltage is VCC = 24V.
SYMBOL
VIH
PARAMETER
Quiescent Current
(No load, Mute = 0V)
Mute Supply Current
(No load, TC2001 Mute = 5V,
TPS1035 Sleep = 5V)
High-level input voltage (MUTE)
IIH = See Mute Control Section
VIL
Low-level input voltage (MUTE)
IIL = See Mute Control Section
ISC
IVPPSENSE
Short circuit current limit
VPPSENSE Threshold Currents
VDD = 24V
Over-voltage turn on (muted)
Over-voltage turn off (mute off)
Under-voltage turn off (mute off)
Under-voltage turn on (muted)
Iq
IMUTE
VVPPSENSE
Threshold Voltages with
RVPPSENSE = 187KΩ
(Note 4, Note 5)
VDD = 24V
V5 = 5V
CONDITIONS
TYP.
20
27
VDD = 24V
V5 = 5V
4
7
Over-voltage turn on (muted)
Over-voltage turn off (mute off)
Under-voltage turn off (mute off)
Under-voltage turn on (muted)
MIN.
MAX.
60
µA
mA
3.5
V
1.0
138
62
25.8
11.6
UNITS
mA
mA
7.5
162
154
79
72
30.3
28.8
14.8
13.5
178
87
33.3
16.3
V
A
µA
µA
µA
µA
V
V
V
V
Note 4: These supply voltages are calculated using the IVPPSENSE values shown in the Electrical Characteristics
table. The typical voltage values shown are calculated using a RVPPSENSE value of 187kohm without any
tolerance variation. The minimum and maximum voltage limits shown include either a +1% or –1% (+1% for
Over-voltage turn on and Under-voltage turn off, -1% for Over-voltage turn off and Under-voltage turn on)
variation of RVPPSENSE off the nominal value. These voltage specifications are examples to show both
typical and worst case voltage ranges for a given RVPPSENSE resistor values of 187kohm. Please refer to
the Application Information section for a more detailed description of how to calculate the over and under
voltage trip voltages for a given resistor value.
Note 5: The fact that the over-voltage turn on specifications exceed the absolute maximum of +26V for the TK2070
does not imply that the part will work at these elevated supply voltages. It also does not imply that the
TK2070 is tested or guaranteed at these supply voltages. The supply voltages are simply a calculation based
on the process spread of the IVPPSENSE currents (see note 7). The supply voltage must be maintained
below the absolute maximum of +26V or permanent damage to the TK2070 may occur.
3
TK2070 – MC/2.1/10-03
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PERFORMANCE CHARACTERISTICS – TK2070
TA = 25 °C. Unless otherwise noted, VCC = 24V, f=1kHz, and the measurement bandwidth is 20kHz.
SYMBOL
POUT
PARAMETER
Output Power
(Continuous Average/Channel)
(Note 13)
THD + N
Total Harmonic Distortion Plus
Noise
IHF-IM
IHF Intermodulation Distortion
SNR
Signal-to-Noise Ratio
CS
Channel Separation
AV
Amplifier Gain
AVERROR
Channel to Channel Gain Error
η
Power Efficiency
eN
Output Noise Voltage
4
CONDITIONS
VCC = 24V, RL = 8Ω
THD+N = 0.02%
THD+N = 1.0%
THD+N = 10.0%
VCC = 24V, RL = 4Ω
THD+N = 0.05%
THD+N = 5.0%
THD+N = 10.0%
POUT = 24W/Channel, RL = 8Ω
VCC = 24V
POUT = 40W/Channel, RL = 4Ω
VCC = 24V
19kHz, 20kHz, 1:1 (IHF), RL = 4Ω
POUT = 10W/Channel
A-Weighted
0dB = 70W/Channel, RL = 4Ω
0dB = 9W, RL = 4Ω, f=1kHz
POUT = 10W/Channel, RL = 8Ω,
See Application / Test Circuit
POUT = 10W/Channel, RL = 8Ω
See Application / Test Circuit
POUT = 35W/Channel, RL = 8Ω
POUT = 70W/Channel, RL = 4Ω
A-Weighted, input AC grounded,
RFBC = 11kΩ , RFBB = 1kΩ
MIN.
TYP.
MAX.
UNITS
22
33
40
W
W
W
45
55
70
0.03
W
W
W
%
0.04
%
95
dB
105
dB
100
dB
12
V/V
0.5
92
86
85
dB
%
%
µV
TK2070 – MC/2.1/10-03
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TC2001 AUDIO SIGNAL PROCESSOR PIN DESCRIPTIONS
Pin
1
Function
BIASCAP
2, 6
FBKGND2,
FBKGND1
DCMP
3
4, 7
Description
Bandgap reference times two (typically 2.5VDC). Used to set the
common mode voltage for the input op amps. This pin is not capable of
driving external circuitry.
Ground Kelvin feedback (Channels 1 & 2)
Internal mode selection. This pin must be grounded for proper device
operation.
Switching feedback (Channels 1 & 2)
5
8
FBKOUT2,
FBKOUT1
VPWR
HMUTE
9, 12
10, 11
13
14, 16
Y1, Y2
Y1B, Y2B
NC
OCD2, OCD1
15
17
REF
VNNSENSE
18
19
OVRLDB
VPPSENSE
20
21
22, 27
23, 28
AGND
V5
OAOUT1, OAOUT2
INV1, INV2
24
MUTE
25, 26
BBM1, BBM0
Test pin. Must be left floating.
Logic output. A logic high indicates both amplifiers are muted, due to the
mute pin state, or a “fault”.
Non-inverted switching modulator outputs.
Inverted switching modulator outputs.
No connect
Over Current Detect pins. Not used on the TK2070, these pins should
be tied to ground.
Internal bandgap reference voltage; approximately 1.2 VDC.
Negative supply voltage sense input. This pin is used for both over and
under voltage sensing for the VNN supply. Not used on the TK2070, this
pin should be tied to ground through a 10kΩ resistor.
A logic low output indicates the input signal has overloaded the amplifier.
Positive supply voltage sense input. This pin is used for both over and
under voltage sensing for the VPP supply.
Analog Ground.
5 Volt power supply input.
Input stage output pins.
Single-ended inputs. Inputs are a “virtual” ground of an inverting op-amp
with approximately 2.4VDC bias.
When set to logic high, both amplifiers are muted and in idle mode.
When low (grounded), both amplifiers are fully operational. If left floating,
the device stays in the mute mode. Ground if not used.
Break-before-make timing control to prevent shoot-through in the output
MOSFETs. When using with the TPS1035, these pins should both be
set to 5V.
TC2001 AUDIO SIGNAL PROCESSOR PINOUT
28-pin SOIC
(Top View)
BIASCAP
1
28
INV2
FBKGND2
2
27
OAOUT2
DCMP
3
26
BBM0
FBKOUT2
4
25
BBM1
VPW R
5
24
MUTE
FBKGND1
6
23
INV1
FBKOUT1
7
22
OAOUT1
HMUTE
8
21
V5
AGND
9
20
Y1B
10
19
VPPSENSE
Y2B
11
18
OVRLDB
Y1
5
Y2
12
17
VNNSENSE
NC
13
16
OCD1
OCD2
14
15
REF
TK2070 – MC/2.1/10-03
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TPS1035 POWER STAGE PIN DESCRIPTIONS
Pin
1
2
3
4
5
6
Function
INPUT
VDD
OUTPUT
PGND
VBOOT
SLEEP
7
BYPASS
8
FAULT
Description
Input pin for power stage.
Positive supply pin.
Output pin.
Power Ground pin.
Bootstrapped voltage to supply drive to gate of high-side output MOSFET.
Sleep Input pin. When set to logic level high, sleep mode is enabled. When set
to logic level low (grounded), sleep mode is disabled.
Bypass pin for the gate drive power supply. The gate drive for the output mosfets
are internally generated from VDD. This pin should be connected to ground
through a 1.0uF or larger capacitor. This pin must be connected to the Fault pin
(pin 8) through a 27kΩ resistor.
Fault Output pin. During normal operation this pin is high. If an overcurrent or
over temperature condition is detected the fault pin will become low. This pin
must be connected to the Bypass pin (pin 7) through a 27kΩ resistor.
TPS1035 POWER STAGE PINOUT
(Top view with heat slug down)
8-pin SOIC with Heatslug
(Top View)
6
INPUT
1
8
FAULT
VDD
2
7
BYPASS
OUTPUT
3
6
SLEEP
PGND
4
5
VBOOT
TK2070 – MC/2.1/10-03
7
RI
20K Ω
RI
20K Ω
*R V P P 1 187K Ω , 1%
*R V P P 2 187K Ω , 1%
V5
V PP
*R V N N 10KΩ
V 5 (Pin 27)
R OFA
50K Ω
Of f set Trim
Circuit
RF
20K Ω
20
C OF
0.1uF
R OFB
1M Ω
27
V P2
25
3
BBM1
DCOMP
V5
-
+
A GND
V5
200K Ω
2.5V
A GND
+
-
V5
A GND
V5
0Ω
9
13
NC
C FB
560pF
FBKGND2
FBKOUT2
A GND
(Pin 28)
OCD2
14
4
2
Y 2B
Y2
HMUTE
C FB
390pF
FBKGND1
FBKOUT1
A GND
(Pin 28)
OCD1
Y 1B
Y1
11
12
8
7
6
16
10
A nalog
Ground
Pow er Ground
Proces s in g
&
Mo du la tio n
Proces s in g
&
Mo du la tio n
TC2001
* The va lu es o fth es e com po n en ts m u s t
b e a dju s ted b as ed o n s up plyvo lta g e
ran g e.See Ap p lica tio n In fo rm a tio n .
19 V PPSENSE
17 V NNSENSE
26
BBM0
C OF
0.1uF
R OFB
1M Ω
INV 2 28
15
24
REF
MUTE
1
INV 1 23
V P1 22
BIA SCA P
RR E F
8.25K Ω , 1%
5V
A GND
RF
20KΩ
CS
0.1uF
CA
0.1uF
V 5 (Pin 27)
CI
2.2uF
+
Of f set Trim
Circuit
R OFA
50KΩ
V 5 (Pin 27)
CI
2.2uF
+
5V
21
*R FB B
1.0K Ω
C FB
560pF
*R FB B
1.0K Ω
C FB
390pF
*R F B C
*R FB B 11.0K Ω
1.0K Ω
*R F B C
11.0K Ω
*R F B C
Ω
*R FB11.0K
B
1.0K Ω
*R F B C
11.0K Ω
CB
1.0uF
CB
1.0uF
CB
1.0uF
CB
1.0uF
RB
27K Ω
RB
27KΩ
RB
27K Ω
RB
27KΩ
FA ULT
6
1
INPUT
8
7
1
6
8
7
1
6
8
SLEEP
FA ULT
BY PA SS
INPUT
SLEEP
FA ULT
BY PA SS
INPUT
SLEEP
7
1
INPUT
BY PA SS
6
8
7
SLEEP
FA ULT
BY PA SS
DB OOT
MURS105T3
D B OOT
MURS105T3
D B OOT
MURS105T3
Input
Logic/
Level
Shift
Internal Regulator
TPS1035
Input
Logic/
Level
Shift
Internal Regulator
TPS1035
Input
Logic/
Level
Shift
Internal Regulator
TPS1035
Input
Logic/
Level
Shift
Internal Regulator
TPS1035
D B OOT
MURS105T3
V DD
V BOOT
V DD
V BOOT
V DD
V BOOT
V DD
V BOOT
4 PGND
3 OUTPUT
2
5
4 PGND
3 OUTPUT
2
5
4 PGND
3 OUTPUT
2
5
4 PGND
3 OUTPUT
2
5
DS
MU R S 1 0 5 T3
DS
MU R S 1 0 5 T3
24V
CB OOT
0.22uF
DS
MU R S 1 0 5 T3
DS
MU R S 1 0 5 T3
24V
CB OOT
0.22uF
DS
MU R S 1 0 5 T3
DS
MU R S 1 0 5 T3
24V
C B OOT
0.22uF
DS
MU R S 1 0 5 T3
DS
MU R S 1 0 5 T3
24V
CB OOT
0.22uF
CH B R
0.1uF
CH B R
0.1uF
CH B R
0.1uF
CH B R
0.1uF
LO
10uH
LO
10uH
LO
10uH
LO
10uH
CO
0.22uF
CZ
0.47uF
RZ
10 Ω , 2 W
CO
0.22uF
CO
0.22uF
CZ
0.47uF
RZ
10Ω , 2 W
CO
0.22uF
OUT2N
CD M
0.1uF
OUT2P
OUT1N
CD M
0.1uF
OUT1P
RL
4 Ω or 8 Ω
RL
4Ω or 8Ω
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APPLICATION / TEST DIAGRAM
TK2070 – MC/2.1/10-03
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E X T E R N A L C O M P O N E N T S D E S C R I P T I O N (Refer to the Application/Test Circuit)
Components
RI
RF
CI
RFBB
RFBC
CFB
ROFA
ROFB
RREF
CS
CZ
RZ
LO
CO
CHBR
CBOOT
DBOOT
CDM
8
Description
Inverting input resistance to provide AC gain in conjunction with RF. This input is
biased at the BIASCAP voltage (approximately 2.5VDC).
Feedback resistor to set AC gain in conjunction with RI. Please refer to the Amplifier
Gain paragraph, in the Application Information section.
AC input coupling capacitor, which, in conjunction with RI, forms a high pass filter at
fC = 1 (2πRICI ) .
Feedback divider resistor connected to AGND. The value of this resistor depends
on the supply voltage setting and helps set the TK2070 gain in conjunction with RI,
RF, RFBA, and RFBC. Please see the Modulator Feedback Design paragraphs in the
Application Information Section.
Feedback resistor connected from either the OUT1A/OUT2A to
FBKOUT1/FBKOUT2 or OUT1B/OUT2B to FBKGND1/FBKGND2. The value of this
resistor depends on the supply voltage setting and helps set the TK2070 gain in
conjunction with RI, RF, RFBA, and RFBB. It should be noted that the resistor from
OUT1/OUT2 to FBKOUT1/FBKOUT2 must have a power rating of greater than
PDISS = VPP2 (2RFBC) . Please see the Modulator Feedback Design paragraphs in the
Application Information Section.
Feedback delay capacitor that both lowers the idle switching frequency and filters
high frequency noise from the feedback signal, which improves amplifier
performance. The value of CFB should be offset between channel 1 and channel 2
so that the idle switching difference is greater than 40kHz. Please refer to the
Application / Test Circuit.
Potentiometer used to manually trim the DC offset on the output of the TK2070.
Resistor that limits the manual DC offset trim range and allows for more precise
adjustment.
Bias resistor. Locate close to pin 15 and ground at pin 20.
Supply decoupling for the power supply pins. For optimum performance, these
components should be located close to the TC2001/TPS1035 and returned to their
respective ground as shown in the Application/Test Circuit.
Zobel capacitor, which in conjunction with RZ, terminates the output filter at high
frequencies. Use a high quality film capacitor capable of sustaining the ripple current
caused by the switching outputs.
Zobel resistor, which in conjunction with CZ, terminates the output filter at high
frequencies. The combination of RZ and CZ minimizes peaking of the output filter
under both no load conditions or with real world loads, including loudspeakers which
usually exhibit a rising impedance with increasing frequency. The recommended
power rating is 1 Watt.
Output inductor, which in conjunction with CO, demodulates (filters) the switching
waveform into an audio signal. Forms a second order filter with a cutoff frequency
of f C = 1 ( 2 π L O C O ) and a quality factor of Q = R L C O L O C O .
Output capacitor, which, in conjunction with LO, demodulates (filters) the switching
waveform into an audio signal. Forms a second order low-pass filter with a cutoff
frequency of f C = 1 ( 2 π L O C O ) and a quality factor of Q = R L C O L O C O . Use
a high quality film capacitor capable of sustaining the ripple current caused by the
switching outputs. Electrolytic capacitors should not be used.
High-frequency bypass capacitor for VCC – GND on each supply pin. A 50V rating is
required for this component.
Boot strap capacitor that enables the charge pump for the high side gate drive for
the internal H-bridge.
Bootstrap diode. This diode charges up the bootstrap capacitor when the output is
at ground to drive the high side gate circuitry. A fast or ultra fast recovery diode is
recommended for the bootstrap circuitry. In addition, the bootstrap diode must be
able to sustain the entire VCC voltage. Thus a 50V (or greater) diode should be
used.
Differential mode capacitor that reduces residual switching noise.
TK2070 – MC/2.1/10-03
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CB
DS
RVPP1
RVPP2
RVNN
CA
RB
9
Bypass capacitor for the internal regulator that powers the gate drive circuitry.
MOSFET protection diode. This diode absorbs any high frequency overshoots or
undershoots caused by the output inductor LO during high output current conditions.
In order for this diode to be effective it must be connected directly to the drain of the
topside MOSFET (pin 2) and the output (pin 3) and source of bottom side MOSFET
(pin 4) and the output (pin 3). An ultra fast recovery diode that can sustain the entire
VCC voltage should be used here. Thus, a 50V or greater diode must be used.
Overvoltage and undervoltage sense resistor for the positive supply (VDD). Please
refer to the Electrical Characteristics Section for the trip points as well as the
hysteresis band. Also, please refer to the Over / Under-voltage Protection section in
the Application Information for a detailed discussion of the internal circuit operation
and external component selection.
Secondary overvoltage and undervoltage sense resistor for the positive supply
(VDD). This resistor accounts for the internal VPPSENSE bias of 2.5V. Nominal
resistor value should be equal to that of RVPP1. Please refer to the Over / Undervoltage Protection section in the Application Information for a detailed discussion of
the internal circuit operation and external component selection.
Not used on TK2070. Connect this pin to AGND through a 10kΩ resistor.
BIASCAP decoupling capacitor. Should be located close to pin 1 of the TC2001 and
grounded at pin 20 of the TC2001.
For proper operation for the TPS1035, the Fault pin (pin 8) must tied to the Bypass
pin (pin 7) through a 27kohm resistor.
TK2070 – MC/2.1/10-03
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TYPICAL PERFORMANCE CHARACTERISTICS
THD+N vs Output Power
5
2
5
f = 1kHz
RL = 4 Ω
VCC = 24V
BW = 22Hz-20kHz
AES 17 Filter
1
THD + N (%)
THD + N (%)
0.5
0.2
0.5
0.2
0.1
0.1
0.05
0.05
0.02
0.02
0.01
1
2
5
20
50
0.01
1
100
2
3
2
1
0.5
0.5
0.2
0.1
0.05
40
50
0.1
0.02
0.01
0.005
20
50
100
200
500
1k
2k
5k
10k
20k
0.005
20
50
100
200
Frequency (Hz)
Intermodulation Distortion
-10
-30
1k
5k
2k
10k
Intermodulation Distortion
+0
-10
VCC = 24V
POUT = 10W/Channel
RL = 4Ω
19kHz, 20kHz 1:1
0dB = 6.3Vrms
BW = 22Hz-20kHz
-20
500
Frequency (Hz)
+0
VCC = 24V
POUT = 10W/Channel
RL = 8Ω
19kHz, 20kHz 1:1
0dB = 9Vrms
BW = 22Hz-20kHz
-20
-30
-40
Amplitude (dBr)
Amplitude (dBr)
30
0.05
0.02
-50
-60
-70
-40
-50
-60
-70
-80
-80
-90
-90
-100
-100
-110
-110
10
20
0.2
0.01
-120
5 6 7 8 9 10
Output Power (W)
VCC = 24V
POUT = 10W/Channel
RL = 8 Ω
BW = 22Hz-20kHz
AES 17 Filter
5
1
4
THD+N vs Frequency
10
VCC = 24V
POUT = 10W/Channel
RL = 4Ω
BW = 22Hz-20kHz
AES 17 Filter
THD + N (%)
THD + N (%)
10
Output Power (W)
THD+N vs Frequency
10
2
f = 1kHz
RL = 8 Ω
VCC = 24V
BW = 22Hz-20kHz
AES 17 Filter
2
1
5
THD+N vs Output Power
10
10
60
100
200
500
1k
2k
Frequency (Hz)
5k
10k
20k 30k
-120
60
100
200
500
1k
2k
Frequency (Hz)
5k
10k
TK2070 – MC/2.1/10-03
20k 30k
20k
Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on
T Y P I C A L P E R F O R M A N C E C H A R A C T E R I S T I C S (cont’d)
Efficiency vs Output Power
Efficiency vs Output Power
100
100
90
90
80
80
70
70
60
Efficiency (%)
Efficiency (%)
60
50
40
30
50
40
30
VCC = 24V
RL = 4Ω
THD+N <10%
20
VCC = 24V
RL = 8Ω
THD+N <10%
20
10
10
0
0
0
10
20
30
40
50
60
70
0
80
5
10
15
Output Power (W)
-10
-20
-30
VCC = 24V
POUT = 9W/Channel
RL = 4Ω
0dB = 8.8Vrms
BW = 22Hz-20kHz
-10
-30
Amplitude (dB)
Amplitude (dB)
-70
10k
20k
5k
10k
-70
-80
-90
-100
-100
-110
-110
50
100
200
500
1k
Frequency (Hz)
2k
5k
10k
-120
20
20k
Noise Floor
+0
50
100
500
1k
Frequency (Hz)
2k
VCC = 24V
RL = 4Ω
0dB = 200mVp-p
Vripple = 200mVp-p
BW = 22Hz-22kHz
-10
VCC = 24V
POUT = 0W/Channel
RL = 4Ω
AV = 12V/V
BW = 22Hz-22kHz
200
Power Supply Rejection Ratio
+0
-20
-30
Amplitude (dB)
-36
Amplitude (dBV)
5k
-50
-90
-48
-60
-72
-40
-50
-60
-70
-84
-80
-96
-90
-108
11
45
-60
-80
-120
20
40
-40
-60
-24
35
VCC = 24V
POUT = 4.5W/Channel
RL = 8Ω
0dB = 6Vrms
BW = 22Hz-20kHz
-20
-50
-12
30
+0
-40
-120
20
25
Channel Seperation vs Frequency
Channel Seperation vs Frequency
+0
20
Output Power (W)
-100
50
100
200
500
1k
Frequency (Hz)
2k
5k
10k
20k
20
50
100
200
500
1k
Frequency (Hz)
2k
TK2070 – MC/2.1/10-03
20k
Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on
APPLICATION INFORMATION
TK2070 Basic Amplifier Operation
The TC2001 is a 5V CMOS signal processor that amplifies the audio input signal and converts the
audio signal to a switching pattern. This switching pattern is spread spectrum with a typical idle
switching frequency of about 650kHz. The switching patterns for the two channels are not
synchronized and the idle switching frequencies should differ by at least 40kHz to avoid increasing
the audio band noise floor. The idle frequency difference can be accomplished by offsetting the value
of CFB for each channel. Typical values of CFB are 390pF for channel 1 and 560pF for channel 2.
The TPS1035 is a MOSFET output stage that level-shifts the signal processor’s 5V switching patterns
to the power supply voltages and drives the power MOSFETs. The power MOSFETs are N-channel
devices configured in half-bridges and are used to supply power to the output load. The outputs of
the power MOSFETs must be low pass filtered to remove the high frequency switching pattern. A
residual voltage from the switching pattern will remain on the speaker outputs when the
recommended output LC filter is used, but this signal is outside of the audio band and will not affect
audio performance.
Circuit Board Layout
The TK2070 is a power (high current) amplifier that operates at relatively high switching frequencies.
The output of the amplifier switches between VDD and GND at high speeds while driving large
currents. This high-frequency digital signal is passed through an LC low-pass filter to recover the
amplified audio signal. Since the amplifier must drive the inductive LC output filter and speaker loads,
the amplifier outputs can be pulled above the supply voltage and below ground by the energy in the
output inductanor. To avoid subjecting the TK2070 to potentially damaging voltage stress, it is critical
to have a good printed circuit board layout. It is recommended that Tripath’s layout and application
circuit be used for all applications and only be deviated from after careful analysis of the effects of any
changes.
The following components are important to place near their associated TC2001/TPS1035 pins and
are ranked in order of layout importance, either for proper device operation or performance
considerations.
-
The capacitors CHBR provide high frequency bypassing of the amplifier power supplies and
will serve to reduce spikes across the supply rails. CHBR should be kept within 1/8” (3mm)
of the VDD pins. Please note that the four VDD pins must be decoupled separately. In
addition, the voltage rating for CHBR should be 50V as this capacitor is exposed to the full
supply range.
-
CFB removes very high frequency components from the amplifier feedback signals and
lowers the output switching frequency by delaying the feedback signals. In addition, the
value of CFB is different for channel 1 and channel 2 to keep the average switching
frequency difference greater than 40kHz. This minimizes in-band audio noise.
-
To minimize noise pickup and minimize THD+N, RFBC should be located as close to the
TC2001 as possible. Make sure that the routing of the high voltage feedback lines is kept
far away from the input op amps or significant noise coupling may occur. It is best to shield
the high voltage feedback lines by using a ground plane around these traces as well as the
input section.
In general, to enable placement as close to the TC2001/TPS1035, and minimize PCB parasitics, the
capacitors listed above (with the exception of the bulk capacitors) should be surface mount types.
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Some components are not sensitive to location but are very sensitive to layout and trace routing.
-
To maximize the damping factor and reduce distortion and noise, the modulator feedback
connections should be routed directly to the pins of the output inductors, LO.
-
The modulator feedback resistors should all be grounded together. These connections will
serve to minimize common mode noise via the differential feedback.
TK2070 Grounding
Proper grounding techniques are required to maximize TK2070 functionality and performance.
Parametric parameters such as THD+N, noise floor and cross talk can be adversely affected if proper
grounding techniques are not implemented on the PCB layout. The following discussion highlights
some recommendations about grounding both with respect to the TK2070 as well as general “audio
system” design rules.
The TK2070 is divided into two sections: the input section, and the output (high power) section. On
the TK2070 evaluation board, the ground is also divided into distinct sections, one for the input and
one for the output. To minimize ground loops and keep the audio noise floor as low as possible, the
input and output ground must be only connected at a single point. Depending on the system design,
the single point connection may be in the form of a ferrite bead or a PCB trace.
Modulator Feedback Design
The modulator converts the signal from the input stage to the high-voltage output signal. The
optimum gain of the modulator is determined from the maximum allowable feedback level for the
modulator and maximum supply voltage for the power stage. Depending on the maximum supply
voltage, the feedback ratio will need to be adjusted to maximize performance. The values of RFBB
and RFBC (see explanation below) define the gain of the modulator. Once these values are chosen,
based on the maximum supply voltage, the gain of the modulator will be fixed even with as the supply
voltage fluctuates due to current draw.
For the best signal-to-noise ratio and lowest distortion, the maximum differential modulator feedback
voltage should be approximately 4Vpp. This will keep the gain of the modulator as low as possible
and still allow headroom so that the feedback signal does not clip the modulator feedback stage.
The modulator feedback resistors are:
RFBB = User specified; typically 1kΩ
 V CC ∗ R FBB 
R FBC = 
 − R FBB
2V


TK2070 Amplifier Gain
The gain of the TK2070 is the product of the input stage gain and the modulator gain. Please refer to
the sections, Input Stage Design, and Modulator Feedback Design, for a complete explanation of how
to determine the external component values.
13
AV
TK2070
= AV
AV
TK2070
≈
INPUT STAGE
* AV
MODULATOR
R F  R FBC + R FBB 


RI 
R FBB

TK2070 – MC/2.1/10-03
Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on
For example, using a TK2070 with the following external components,
RI = 20kΩ
RF = 20kΩ
RFBB = 1kΩ
RFBC = 11kΩ
AV
TK2070
≈
20k Ω  11k Ω + 1k Ω ) 
V

 = 12
20k Ω 
1k Ω
V

Please note that OUT1P (OUT2P), as shown in the Application/Test Diagram, is out of phase with
respect to the input signal. This phase reversal can be eliminated by connecting OUT1N and OUT2N
to the positive terminal at the speaker.
Input Stage Design
The TC2001 input stage is configured as an inverting amplifier, allowing the system designer flexibility
in setting the input stage gain and frequency response. Figure 1 shows a typical application where
the input stage is a constant gain inverting amplifier. The input stage gain should be set so that the
maximum input signal level will drive the input stage output to 4Vpp.
TC2001
OAOUT1
CI
V5
RF
RI
INV1
INPUT1
+
BIASCAP
AGND
V5
+
INV2
CI
-
RF
RI
INPUT2
OAOUT2
AGND
Figure 1: Input Stage
The gain of the input stage, above the low frequency high pass filter point, is that of a simple inverting
amplifier: It should be noted that the input amplifiers are biased at approximately 2.5VDC. Thus, the
polarity of CI must be followed as shown in Figure 1 for a standard ground referenced input signal
AV
INPUT STAGE
= −
RF
RI
Input Capacitor Selection
CI can be calculated once a value for RI has been determined. CI and RI determine the input low
frequency pole. Typically this pole is set below 10Hz. CI is calculated according to:
CI =
1
2π f P R I
where:
RI = Input resistor value in ohms.
fP = Input low frequency pole (typically 10Hz or below)
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Mute Control
When a logic high signal is supplied to MUTE, both amplifier channels are muted (both high- and lowside transistors are turned off). When a logic level low is supplied to MUTE, both amplifiers are fully
operational. There is a delay of approximately 200 milliseconds between the de-assertion of MUTE
and the un-muting of the TK2070.
To ensure proper device operation, including minimization of turn on/off transients that can result in
undesirable audio artifacts, Tripath recommends that the TK2070 device be muted prior to power up
or power down of the 5V supply. The “sensing” of the V5 supply can be easily accomplished by using
a “microcontroller supervisor” or equivalent to drive the TC2001 mute pin high when the V5 voltage is
below 4.5V. This will ensure proper operation of the TK2070 input circuitry. A micro-controller
supervisor such as the MCP101-450 from Microchip Corporation has been used by Tripath to
implement clean power up/down operation.
If turn-on and/or turn-off noise is still present with a TK2070 amplifier, the cause may be other
circuitry external to the TK2070. While the TK2070 has circuitry to suppress turn-on and turn-off
transients, the combination of power supply and other audio circuitry with the TK2070 in a particular
application may exhibit audible transients. One solution that will completely eliminate turn-on and
turn-off pops and clicks is to use a relay to connect/disconnect that amplifier from the speakers with
the appropriate timing during power on/off.
TK2070 Output Capability
The TK2070 can drive two 4 Ohm loads with 70 Watts 10% THD+N. The maximum sustained
amplifier output power will be determined by a number of factors including the TC2001/TPS1035
junction temperatures, the load impedance and the power supply voltage.
Tripath does not recommend driving loads below 4 Ohms bridged as the amplifier efficiency will be
reduced and the amplifier will reach it’s current limit at relatively low power output levels. With the
outputs connected in parallel, however, the TK2070 is capable of driving single channel loads down
to 2 Ohms with very high power capability. Please refer to the RB-TK2070 datasheet for parallel
mode operation of the TK2070.
Output Voltage Offset
The TK2070 does not have internal compensation for DC offset. The output offset voltage must be
trimmed with a potentiometer at the INV1/INV2 pins of the TC2001. If the output offset voltage is not
trimmed the efficiency of the TK2070 will be significantly reduced and the idle current will be
significantly increased.
Output Filter Design
Tripath amplifiers generally have a higher switching frequency than PWM implementations, allowing
the use of higher cutoff frequency filters and reducing the load dependent peaking/drooping in the
20kHz audio band. This is especially important for applications where the end customer may attach
any speaker to the amplifier (as opposed to a system where speakers are shipped with the amplifier),
since speakers are not purely resistive loads and the impedance they present changes over
frequency and from speaker model to speaker model. An RC network, or “Zobel” (RZ, CZ) should be
placed at the filter output to control the impedance “seen” by the TP2051 when not attached to a
speaker load. The TK2070 works well with a 2nd order, 80kHz LC filter with LO = 10uH and CO =
0.47uF and RZ = 10 Ohm/1W and CZ = 0.47uF.
Output inductor selection is a critical design step. The core material and geometry of the output filter
inductor affects the TK2070 distortion levels, efficiency, power dissipation and EMI output.
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TK2070 – MC/2.1/10-03
Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on
Wound iron powder toroidal cores are the recommended inductor choice for the TK2070. Toroidal
cores have less flux leakage compared to shielded bobbin or shielded SMD inductors, resulting in
reduced EMI and improved channel separation. For typical applications we recommend the
Micrometals Type-2 iron powder (Carbonyl-E) core. This core material has low permeability metal
powder and a distributed air gap for increased energy storage capability. This allows for a small
footprint with high peak current capability.
Minimum and Maximum Supply Voltage Operating Range
The TK2070 can operate over a wide range of power supply voltages from +7.5V to +25V. In order to
optimize operation for either the low or high range, the user must select the proper values for RFBB,
and RFBC.
Over- and Under-Voltage Protection
The TC2001 senses the power rails through external resistor networks connected to VPPSENSE.
The over- and under-voltage limits are determined by the values of the resistors in the networks, as
described in the table “Test/Application Circuit Component Values”. If the supply voltage falls outside
the upper and lower limits determined by the resistor networks, the TC2001 shuts off the TPS1035
output stage. The removal of the over-voltage or under-voltage condition returns the TK2070 to
normal operation. Please note that trip points specified in the Electrical Characteristics table are at
25°C and may change over temperature.
The TC2001 has built-in over and under voltage protection the VDD supply rail. The nominal
operating voltage will typically be chosen as the supply “center point.” This allows the supply voltage
to fluctuate, both above and below, the nominal supply voltage. For the TK2070 only the VDD supply
rail will be sensed and the VNN sensing will not be used so pin 17 of the TC2001 will be shorted to
ground.
VPPSENSE (pin 19) performs the over and undervoltage sensing for the positive supply, VDD. When
the current through RVPPSENSE goes below or above the values shown in the Electrical Characteristics
section (caused by changing the power supply voltage), the TK2070 will be muted. VPPSENSE (pin
19) is internally biased at 2.5V.
Once the supply comes back into the supply voltage operating range (as defined by the supply sense
resistors), the TK2070 will automatically be unmuted and will begin to amplify. There is a hysteresis
range on both the VPPSENSE and VNNSENSE pins. If the amplifier is powered up in the hysteresis
band the TK2070 will be muted. Thus, the usable supply range is the difference between the overvoltage turn-off and under-voltage turn-off for the VDD supply. It should be noted that there is a timer
of approximately 200mS with respect to the over and under voltage sensing circuit. Thus, the supply
voltage must be outside of the user defined supply range for greater than 200mS for the TK2070 to
be muted.
The equation for calculating RVPP1 is as follows:
R VPP1 =
VPP
I VPPSENSE
Set R VPP2 = R VPP1 .
IVPPSENSE can be any of the currents shown in the Electrical Characteristics table for
VPPSENSE.
RVPP2 compensates for the internal bias point. Thus, RVPP1 can be used for the direct calculation of
the actual VCC trip voltage without considering the effect of RVPP2.
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Using the resistor values from above, the actual minimum over voltage turn off points will be:
VPP MIN_OV_TUR
N_OFF
= R VPP1 × I VPPSENSE
(MIN_OV_TU RN_OFF)
The other three trip points can be calculated using the same formula but inserting the appropriate
IVPPSENSE current value. As stated earlier, the usable supply range is the difference between the
minimum overvoltage turn off and maximum under voltage turn-off for the VPP supply.
VPP RANGE = VPP MIN_OV_TUR
N_OFF
- VPP MAX_UV_TUR
N_OFF
Protection Circuits
The TK2070 is protected against over-current, over / under-voltage and over-temperature conditions.
Output overcurrent conditions are detected on the TPS1035.
TPS1035
8 FAULT
FD LL914
1K Ω
5V
5V
10K Ω
510K Ω
2N 3906
MUTE Pin
(Pin 24 of TC2001)
20K Ω
TPS1035
8 FAULT
FD LL914
1K Ω
Figure 2
Figure 2 shows an overcurrent detection circuit that will mute the amplifier whenever the TPS1035
detects an overcurrent condition. The fault pin (pin 8 of the TPS1035) is a overcurrent indicator that
is high (approximately 5.4V) during normal operation and low (0V) if an overcurrent condition is
detected. The fault pin will go low and turn on the PNP transistor and pull the Mute pin to 5V if the
switch is closed. In this circuit, whenever the switch is open the Mute pin will be at 5V and the
amplifier will be muted.
Over-temperature Protection
An over-temperature fault occurs if the junction temperature of the part exceeds approximately
165°C. The thermal hysteresis of the part is approximately 30°C, therefore the fault will automatically
clear when the junction temperature drops below 135°C.
HMUTE
The HMUTE pin on the TC2001 is a 5V logic output that indicates various fault conditions within the
device. These conditions include: over-current, overvoltage and undervoltage. The HMUTE output is
high whenever a fault condition occurs and is capable of directly driving an LED through a series 2kΩ
resistor.
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OVRLDB
The OVRLDB pin is a 5V logic output that is asserted just at the onset of clipping. When low, it
indicates that the level of the input signal has overloaded the amplifier resulting in increased distortion
at the output. The OVRLDB signal can be used to control a distortion indicator light or LED through a
transistor, as the OVRLDB cannot drive an LED directly. There is a 20K resistor on chip in series with
the OVRLDB output.
Performance Measurements of the TK2070
The TK2070 operates by generating a high frequency switching signal based on the audio input. This
signal is sent through a low-pass filter (external to the Tripath amplifier) that recovers an amplified
version of the audio input. The frequency of the switching pattern is spread spectrum in nature and
typically varies between 100kHz and 1MHz, which is well above the 20Hz – 20kHz audio band. The
pattern itself does not alter or distort the audio input signal, but it does introduce some inaudible
components.
The measurements of certain performance parameters, particularly noise related specifications such
as THD+N, are significantly affected by the design of the low-pass filter used on the output as well as
the bandwidth setting of the measurement instrument used. Unless the filter has a very sharp roll-off
just beyond the audio band or the bandwidth of the measurement instrument is limited, some of the
inaudible noise components introduced by the TK2070 amplifier switching pattern will degrade the
measurement.
One feature of the TK2070 is that it does not require large multi-pole filters to achieve excellent
performance in listening tests, usually a more critical factor than performance measurements.
Though using a multi-pole filter may remove high-frequency noise and improve THD+N type
measurements (when they are made with wide-bandwidth measuring equipment), these same filters
degrade frequency response. The TK2070 Reference Board uses the Application/Test Circuit of this
data sheet, which has a simple two-pole output filter and excellent performance in listening tests.
Measurements in this data sheet were taken using this same circuit with a limited bandwidth setting in
the measurement instrument.
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TK2070 – MC/2.1/10-03
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PACKAGE INFORMATION – TC2001
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TK2070 – MC/2.1/10-03
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Package Information – TPS1035
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TK2070 – MC/2.1/10-03
Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on
Tripath and Digital Power Processing are trademarks of Tripath Technology Inc. Other trademarks
referenced in this document are owned by their respective companies.
Tripath Technology Inc. reserves the right to make changes without further notice to any products
herein to improve reliability, function or design. Tripath does not assume any liability arising out of the
application or use of any product or circuit described herein; neither does it convey any license under
its patent rights, nor the rights of others.
TRIPATH’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE
SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN CONSENT OF THE
PRESIDENT OF TRIPATH TECHNOLOGY INC. As used herein:
1. Life support devices or systems are devices or systems which, (a) are intended for surgical
implant into the body, or (b) support or sustain life, and whose failure to perform, when properly
used in accordance with instructions for use provided in this labeling, can be reasonably expected
to result in significant injury to the user.
2. A critical component is any component of a life support device or system whose failure to perform
can be reasonably expected to cause the failure of the life support device or system, or to affect
its safety or effectiveness.
For more information on Tripath products, visit our web site at: http://www.tripath.com
Contact Information
TRIPATH TECHNOLOGY, INC
2560 Orchard Parkway, San Jose, CA 95131
408.750.3000 - P
408.750.3001 - F
For more Sales Information, please visit us @ www.tripath.com/cont_s.htm
For more Technical Information, please visit us @ www.tripath.com/data.htm
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TK2070 – MC/2.1/10-03