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 BENEFITS Single Supply Operation Very High Efficiency Wide Dynamic Range Compact Layout 1 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 RB-TK2019 – MC/1.0/12-03 Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on OPERATING INSTRUCTIONS BOARD CONNECTION DIAGRAM J1 MUTE H-MUTE ** R24 JP1 JP3 + GND, OUT2, GND, OUT1 + V5 - R16 JP2 V5 G5 GND VCC RB-TK2019 Audio Source -+ V5 VCC - OUT2, G5 + OUT1, G5 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. 2 RB-TK2019 – MC/1.0/12-03 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 widebandwidth 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) 3 RB-TK2019 – MC/1.0/12-03 Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on EVALUATION BOARD SCHEMATIC 4 RB-TK2019 – MC/1.0/12-03 Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on EVALUATION BOARD SCHEMATIC (cont.) 5 RB-TK2019 – MC/1.0/12-03 Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on EVALUATION BOARD SCHEMATIC (cont.) 6 RB-TK2019 – MC/1.0/12-03 Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on EVALUATION BOARD BILL-OF-MATERIALS EVALUATION BOARD BILL-OF-MATERIALS (cont.) EVALUATION BOARD LAYOUT EVALUATION BOARD LAYOUT (cont.) EVALUATION BOARD BILL-OF-MATERIALS (cont.) 7 RB-TK2019 – MC/1.0/12-03 Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on EVALUATION BOARD BILL-OF-MATERIALS (cont.) 8 RB-TK2019 – MC/1.0/12-03 Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on EVALUATION BOARD LAYOUT 9 RB-TK2019 – MC/1.0/12-03 Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on EVALUATION BOARD LAYOUT (cont.) 10 RB-TK2019 – MC/1.0/12-03 Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on EVALUATION BOARD LAYOUT (cont.) 11 RB-TK2019 – MC/1.0/12-03