Tr i path Technol ogy, I nc. - Technical Information
RB-TK2019
2 X 20W CLASS-T DIGITAL AUDIO AMPLIFIER REFERENCE
BOARD
Technical Information- Board Rev. 2.1
Revision 2.0 – December 2003
GENERAL DESCRIPTION
The RB-TK2019 Revision 2.1 is a stereo single ended 20W continuous average power per channel
audio amplifier designed to provide a simple and straightforward environment for the evaluation of the
TK2019 as a single ended amplifier. For additional documentation on the TK2019, see the TK2019
Data Sheet.
APPLICATIONS
4Ω and
8 Ω
stereo
Home Theater Receivers
Powered DVD Systems
Mini/Micro Systems
FEATURES
High Continuous Power: 20W @ 4Ω, 10% THD+N
11W @ 8Ω, 10% THD+N
Low Noise Floor: 82uV A-weighted
Low Distortion: .03% THD+N, 11W, 4Ω
.03% THD+N, 6W, 8Ω
High Efficiency: 89% @ 20W, 4Ω
92% @ 11W, 8Ω
Dynamic Range >100dB
BENEFITS
Single Supply Operation
Very High Efficiency
Wide Dynamic Range
Compact Layout
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Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on
OPERATING INSTRUCTIONS
BOARD CONNECTION DIAGRAM
J1
V5
MUTE
H-MUTE
GND, OUT2, GND, OUT1
JP3
R24
JP1
R16
JP2
V5 G5
GND VCC
RB-TK2019
Audio Source
OUT2, G5
V5
POWER SUPPLIES
Two external power supplies are required to operate the RB-TK2019 Revision 2.0: VCC (referenced to GND),
and V5 (referenced to G5). The V5 ground (G5) must be kept separate from the VCC ground (GND). GND and
G5 are joined at a common point on the PCB with a 0Ω resistor (R1).
The Minimum and Maximum VCC supply voltages are 15V and 25V, respectively.
The V5 supply voltage is 5V. Please see the TK2019 Data Sheet for Minimum and Maximum values.
The VCC and V5 power supply connection (JP2) is a standard 4 pin, .156” Molex header. Please refer to the
Board Connection Diagram for the connector locations.
OUTPUT
The output connection for each channel of the RB-TK2019 Revision 2.0 is a standard 4 pin, .156” Molex header.
The output of the RB-TK2019 Revision 2.0 is single ended; therefore each output has a positive output (OUT1
and OUT2) and a ground (GND).
Please refer to the Board Connection Diagram for the connector locations.
INPUT
The input connection for each channel of the RB-TK2019 Revision 2.0 is made using a dual RCA connector
(JP1). The RCA connectors are labeled IN1 and IN2 on the bottom of the PCB. Channel 1’s RCA is color
coded black and Channel 2’s RCA is color-coded red. These inputs share a common ground referenced to G5.
Please refer to the Board Connection Diagram for the connector locations.
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RB-TK2019 – MC/1.0/12-03
-
OUT1, G5
-+
VCC
+
+
-
-
**
+
Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on
JUMPER SETTINGS
J1 is a 2-pin header for the MUTE control. With the jumper shorting the header pins the part is un-muted. When
the jumper is removed the mute pin is pulled high (5V) and the amplifier is muted. Please refer to the Board
Connection Diagram for location of J1.
INDICATOR LED’S
The RB-TK2019 Revision 2.0 has one red LED labeled H-MUTE. The HMUTE LED will glow red and both
outputs are muted when a fault occurs or the MUTE header (J1) is opened. Please refer to the TK2019 Data
Sheet for a complete description of HMUTE. Please refer to the Board Connection Diagram for the LED
location.
OUTPUT OFFSET NULL
There are two potentiometers, R16 (Channel 1) and R24 (Channel 2) that are used to manually trim the output
offset to half of the supply rail voltage (VCC). Because this board uses an output DC blocking capacitor the
offset measurement must be made at or before C62 and C63 and not at the output header. Please refer to the
Board Connection Diagram for the potentiometer locations. The offset should be trimmed to VCC/2 or +12V for
a 24V supply. Although the idle current is not affected by the offset, the output power will be reduced if the
output offset is not properly trimmed. The Evaluation board is shipped with the offset nulled within +/-10mV for a
24V supply.
GAIN SETTING
The gain of the RB-TK2019 Rev 2.0 is set to 10V/V. The gain of the TK2019 is the product of the TC2001
(control stage) gain and the TPS1035 (power stage) gain. The control stage gain is set to unity. Before
changing the gain of the RB-TK2019 Rev 2.0, please refer to the Amplifier Gain section of the TK2019 Data
Sheet.
PERFORMING MEASUREMENTS ON THE RB-TK2019 REV 2.1:
The RB-TK2019 Rev 2.1 operates by generating a high frequency switching signal based on the audio input.
This signal is sent through a low-pass filter 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 TK2019 amplifier switching pattern will degrade the measurement by including
out of band (audio) energy.
One feature of the TK2019 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 RB-TK2019 Rev 2.1
has a simple two-pole output filter with excellent performance in listening tests.
(See Application Note 4 for additional information on bench testing)
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