august 2009 doc id 14535 rev 1 1/8 AN2725 application note demonstration board user guidelines for the ts2012 filter-free stereo 2 x 2.8 w class d audio power amplifier introduction this application note applies to the steval-cca007v1 demonstration board, designed to evaluate the stereo class d audio differential amplifier ts2012. the document provides: a brief description of the ts2012 device, a description of the demonstration board and all of its components, the layout of the demonstration board. about the ts2012 the ts2012 is a fully-differential class d stereo power amplifier that can drive up to 1.35 w into an 8 load at 5 v per channel. it achieves outstanding efficiency compared to typical class ab audio amplifiers. the device has four different gain settings that use two digital pins: g0 and g1. pop and click reduction circuitry provides low on/off switch noise while allowing the device to start within 1 ms. two standby pins (active low) allow each channel to be switched off independently. the ts2012 is available in a 4 x 4 mm qfn20 package. key features of the ts2012 operating range from v cc = 2.5 to 5.5 v standby mode active low output power per channel: 1.35 w at 5 v or 0.68 w at 3.6 v into 8 with 1% thd+n max output power per channel: 2.2 w at 5 v into 4 with 1% thd+n max four gain select settings: 6, 12, 18, 24 db low current consumption psrr: 70 db typ at 217 hz with 6 db gain fast start-up phase: 1 ms thermal shutdown protection qfn20 4 x 4 mm lead-free package refer to the datasheet for complete information on the ts2012. www.st.com
description of the demonstration board AN2725 2/8 doc id 14535 rev 1 1 description of the demonstration board the steval-cca007v1 is designed to evaluate the ts2012, a fully-differential class d stereo power amplifier. the ts2012 device, available in a qfn package, is mounted on a two-layer pcb with a copper area acting as a heatsink. easily-accessible on-board connectors are used to change or drive the gain select pins (g0 and g1) and the standby control pins. the input configuration of the ts2012 can also be changed. the differential gain of the ts2012 can be set to 6, 12 18, or 24 db, depending on the logic level of the g0 pin (connected to pin 2 of the p3) and g1 pin (connected to pin 2 of the p2). note: there is an internal 300 k (+/-20%) resistor between pins g0, g1 and gnd. when the pins are floating (p2 and p3 included), the gain is 6 db. in full standby mode (left and right channels off), these resistors are disconnected (hiz input). the input configuration is either capacitor-coupled or common-mode feedback. on the board, the connectors for the left channel (p13 and p14) and those for the right channel (p23 and p24) allow you to change the input configuration. in the capacitor-coupled configuration , the -3 db cut-off frequency f c in hz is: with z in in (z in = 30 k typically), c in in farads, c13 = c14 and c23 = c24. note: on the ts2012 demonstration board c in = c13 = c14 = c23 = c24 = 220 nf, which means that f c = 24.1 hz for both channels. more information on component calculations is available in the ts2012 datasheet. table 1. gain settings with g0 and g1 pins g1 g0 p2 p3 gain (db) gain (v/v) 00 62 01 124 10 188 1 1 24 16 ` 12 3 ` 12 3 ` 12 3 ` 12 3 ` 12 3 ` 12 3 ` 12 3 ` 12 3 f c 1 2 z in c in ?? ------------------------------------- =
AN2725 description of the demonstration board doc id 14535 rev 1 3/8 caution: when you apply the power supply through p1, do not invert the polarity as this will irreversibly damage the u1 amplifier. table 2. demonstration board connectors connector(s) description p1 power connector (v cc and gnd). power supply voltage from 2.5 to 5.5 v. p2, p3 gain setting connectors - p2 for the g1 pin, p3 for the g0 pin of the ts2012. the connector pins are connected as follows: ? 1 to v cc ? 2 of p2 to the g1 pin ? 2 of p3 to the g0 pin ? 3 to gnd jumper positions: ? logical "1": pins 1 and 2 are shorted ? logical "0": pins 2 and 3 are shorted p4, p5 standby control connector - p4 for the right channel, p5 for the left channel. the connector pins are connected as follows: ? 1 to v cc ? 2 of p4 to the stbyr pin of the ts2012 ? 2 of p5 to the stbyl pin of the ts2012 ? 3 to gnd jumper positions: ? when pins 1 and 2 are shorted, the channel is operating. ? when pins 2 and 3 are shorted or pin 2 is floating, the channel is in standby mode. p11 left channel positive input signal connectors (active input signal l in + and gnd) p12 left channel negative input signal connectors (active input signal l in - and gnd) p21 right channel positive input signal connectors (active input signal r in + and gnd) p22 right channel negative input signal connectors (active input signal r in - and gnd) p13, p14, p23, p24 input configuration: ? capacitor coupled when p13 and p1 4 (p23 and p24) are disconnected. ? common-mode feedback when p13 and p14 (p23 and p24) are shorted by jumpers. p15 left channel output signal connec tor (positive and negative output) p25 right channel output signal connector (positive and negative output) ` 12 3 ` 12 3 ` 12 3 ` 12 3
description of the demonstration board AN2725 4/8 doc id 14535 rev 1 figure 1. schematic diagram gain select gain select standby control pwm h bridge pwm h bridge oscillator lin + lin - rin - rin + g0 g1 stby l stby r av agnd pgnd pgnd lout+ lout- cc pv cc pv cc rout+ rout- u1 ts2012iqt vcc vcc vcc gnd gnd gnd 1 2 3 p5 standbyl 1 2 3 p4 standbyr 1 2 3 p2 g1 1 2 3 p3 g0 1 2 p15 lout 1 2 p25 rout vcc vcc gnd gnd vcc vcc gnd gnd 1 2 p11 lin+ 1 2 p12 lin- 1 2 p21 rin+ 1 2 p22 rin- gnd gnd gnd gnd 220nf c13 220nf c14 220nf c23 220nf c24 1 2 p13 1 2 p14 1 2 p23 1 2 p24 1 2 p1 c1 1uf c2 1uf 100nf c3 vcc gnd gnd gnd gnd table 3. demonstration board component list designation quantity description c1, c2, c3 3 1 f/16 v, smd ceramic capacitors, 0603 c12, c14, c23, c24 4 220 nf/16 v, smd ceramic capacitor, 0603 p1, p11, p12, p13, p14, p15, p21, p22, p23, p24, p25 11 2-pin header, 2.54 mm pitch p2, p3, p4, p5 4 3-pin header, 2.54 mm pitch u1 1 ts2012iqt
AN2725 demonstration board layout doc id 14535 rev 1 5/8 2 demonstration board layout the following schematics show the layers and top view of the demonstration board. figure 4. demonstration board top view and dimensions figure 2. pcb top layer figure 3. pcb bottom layer
conclusion AN2725 6/8 doc id 14535 rev 1 3 conclusion to order the board online, go to http://www.st.com/stonline/domains/buy/buy_dev.htm , and use the order code steval-cca007v1.
AN2725 revision history doc id 14535 rev 1 7/8 4 revision history table 4. document revision history date revision changes 28-aug-2009 1 initial release.
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