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www.irf.com rd-0617 iraudamp4 120 w x 2 channel class d audio power amplifier using IRS20955 and irf6645 by johan strydom, jun honda, and jorge cerezo table of contents page introduction .......................................................................................... 1 specificatio ns ....................................................................................... 2 functional descr iption.......................................................................... 4 startup and s hutdown ..........................................................................12 protecti on .............................................................................................16 typical perf ormanc e ............................................................................21 design docu ments ..............................................................................27 caution: international rectifier s uggests the following guidelines for safe operation and handling of iraudamp4 demo board; ? always wear safety glasses when ever operating demo board ? avoid personal contact with expo sed metal surfaces when operating demo board ? turn off demo board when placing or removing measurement probes
www.irf.com 1 rd-0617 introduction the iraudamp4 reference design is an exam ple of a two-channel 120 w half-bridge class d audio power amplifier. the reference design will demonstrate how to use the IRS20955, implement protection circuits, and design an optimum pcb layout using the irf6645 directfet mosfets. the resulting design requires no heatsink for normal operation (one-eighth of continuous rated power). the reference design contains all the required housekeeping power supplies for ease of use. the two-channel design is scalable, for power and the number of channels. applications av receivers home theater systems mini component stereos sub-woofers features output power: 120 w x two channels, total harmonic distortion (thd) = 1%, 1 khz residual noise: 52 v, ihf-a weighted, aes-17 filter distortion: 0.004% thd+n @ 60 w, 4 ? efficiency: 96% @ 120 w, 4 ? , single-channel driven, class d stage multiple protection features: over-current protection (ocp), over-voltage protection (ovp), under-voltage protection (uvp), dc-protection (dcp), over-temperature protection (otp) pwm modulator: self-oscillating half-bridge topology with optional clock synchronization
www.irf.com 2 rd-0617 specifications general test conditions (unless othe rwise noted) notes / conditions supply voltage 35 v load impedance 4 ? self-oscillating frequency 400 khz no input signal gain setting 26.8 db 1 vrms input yields rated power electrical data typical notes / conditions ir devices used IRS20955 gate driver, irf6645 directfet mosfet modulator self-oscillating, second order sigma-delta modulation, analog input power supply range 25 - 35 v output power ch1-2: (1% thd+n) 120 w 1 khz output power ch1-2: (10% thd+n) 170 w 1 khz rated load impedance 4 ? supply current 100 ma no input signal total idle power consumption 7 w no input signal channel efficiency 96% single-channel driven, 120 w, class d stage audio performance typical / class d* notes / conditions thd+n, 1 w thd+n, 10 w thd+n, 60 w 0.005% 0.002% 0.004% 0.002% 0.001% 0.003% 1 khz, single-channel driven dynamic range 113 db 120 db a-weighted, aes-17 filter, single-channel operation residual noise, 20hz - 20 khz bw, a-weighted 70 v 50 v 40 v 20 v self-oscillating ? 400 khz internal clock ? 300 khz damping factor 170 2000 1 khz, relative to 4 ? load channel separation 95 db 80 db 100 db 85 db 100 hz 10 khz frequency response : 20hz-20 khz : 20hz-40 khz 1 db 3 db 1w, 4 ? - 8 ? load thermal performance typical notes / conditions idling t c =30 c t pcb =37 c no signal input, t a =25 c 2ch x 15 w (1/8 rated power) t c =54 c t pcb =67 c continuous, t a =25 c 2ch x 120 w (rated power) t c =80 c t pcb =106 c at otp shutdown @ 150 s, t a =25 c physical specifications dimensions 5.8 in (l) x 5.2 in (w) note: specifications are typical and not guaranteed * class d refers to audio performance measurements of the class d output power stage only, with preamp and output filter bypassed.
www.irf.com 3 rd-0617 connection diagram figure 1. typical test setup pin description ch1 in j6 analog input for ch1 ch2 in j5 analog input for ch2 power j7 positive and negative supply (+b / -b) ch1 out j3 output for ch1 ch2 out j4 output for ch2 ext clk j8 external clock sync dcp out j9 dc protection relay output power-on and power-off procedure always apply or remove 35 v bus supplies at the same time. volume j6 j5 j3 j4 j7 r113 s3 s2 tp1 tp2 ch1 output ch2 output ch1 input ch2 input g protection normal s1 led 35 v, 5 a dc supply 4 ? 4 ? 35 v, 5 a dc supply 250 w, non-inductive resistors j8 j9 audio signal generator
www.irf.com 4 rd-0617 functional description class d operation referring to ch1 as an example, the op-amp u1 forms a front-end second-order integrator with c11, c13 & r25 + r29p. this integrator receives a rectangular feedback waveform from the class d switching stage and outputs a quadratic oscillatory waveform as a carrier signal. to create the modulated pwm signal, the input signal shifts the average value of this quadratic waveform (through gain relationship between r13 and r31 + r33) so that the duty varies according to the instantaneous value of the analog input signal. the IRS20955 input comparator processes the signal to create the required pwm signal. this pwm signal is internally level-shifted down to the negative supply rail where this signal is split into two signals, with opposite polarity and added deadtime, for high-side and low-side mosfet gate signals, respectively. the IRS20955 drives two irf6645 directfet mosfets in the power stage to provide the amplified pwm waveform. the amplified analog output is re-created by demodulating the amplified pwm. this is done by means of the lc low-pass filter (lpf) formed by l1 and c23, which filters out the class d switching carrier signal. figure 2. simplified block diagram of class d amplifier power supplies the iraudamp4 has all the necessary housekeeping power supplies onboard and only requires a pair of symmetric power supplies ra nging from 25 v to 35 v (+b, gnd, -b) for operation. the internally-generated housekeeping power supplies include a 5 v supply for analog signal processing (preamp, etc.), while a +12 v supply (v cc ), referenced to ?b, is included to supply the class d gate-driver stage. for the externally-applied power, a regulated power supply is preferable for performance measurements, but not always necessary. the bus capacitors, c31 and c32 on the motherboard, along with high-frequency bypass-caps c15-c18 on daughter board, address the high-frequency ripple current that result from switching action. in designs involving unregulated power supplies, the designer should place a set of bus capacitors, having enough capacitance to handle the audio-ripple current, externally. overall regulation and output voltage ripple for the power supply design are not critical when using the iraudamp4 class d amplifier as the power supply rejection ratio (psrr) of the iraudamp4 is excellent (figure 3). irf6645 direct-fet feedback gnd lpf +b -b IRS20955s gate driver u1 u1 daughter-board integrator pwm modulator and level shifter
www.irf.com 5 rd-0617 figure 3. power supply rejection ratio (psrr) for negative (-b) and positive (+b) supplies bus pumping since the iraudamp4 is a half-bridge conf iguration, bus pumping does occur. under normal operation during the first half of the cycle, energy flows from one supply through the load and into the other supply, thus causing a voltage imbalance by pumping up the bus voltage of the receiving power supply. in the second half of the cycle, this condition is reversed, resulting in bus pumping of the other supply. these conditions worsen bus pumping: ? lower frequencies (bus-pumping duration is longer per half cycle) ? higher power output voltage and/or lower load impedance (more energy transfers between supplies) ? smaller bus capacitors (the same energy will cause a larger voltage increase) the iraudamp4 has protection features that will shutdown the switching operation if the bus voltage becomes too high (>40 v) or too low (<20 v). one of the easiest countermeasures is to drive both of the channels out of phase so that one channel consumes the energy flow from the other and does not return it to the power supply. bus voltage detection is only done on the ?b supply as the effect of the bus pumping on the supplies is assumed to be symmetrical in amplitude (although opposite in phase). input a proper input signal is an analog signal below 20 khz, up to 3.5 v peak, having a source impedance of less than 600 ? . a 30 khz to 60 khz input signal can cause lc resonance in the output lpf, resulting in an abnormally large amount of reactive current flowing through the switching stage (especially at 8 ? or higher impedance towards open load), causing ocp activation. the iraudamp4 has an rc network, or zobel network, to damp the resonance and protect the board in such event, but is not thermally rated to handle continuous supersonic frequencies. these supersonic input frequencies therefore should be avoided. separate mono rca connectors provide input to each of the two channels. although both channels share a common ground, it is necessary to connect each channel separately to limit noise and crosstalk between channels. -90 +0 -80 -70 -60 -50 -40 -30 -20 -10 d b 20 40k 50 100 200 500 1k 2k 5k 10k 20k hz +b -b
www.irf.com 6 rd-0617 output both outputs for the iraudamp4 are single-ended and therefore have terminals labeled (+) and (-) with the (-) terminal connected to power ground. each channel is optimized for a 4 ? speaker load for a maximum output power of 120 w, but is capable of operating with higher load impedances (at reduced power), at which point the frequency response will have a small peak at the corner frequency of the output lc low pass filter. the iraudamp4 is stable with capacitive-loading; however, it should be realized that the frequency response degrades with heavy capacitive loading of more than 0.1 f. gain setting / volume control the iraudamp4 has an internal volume control (potentiometer r108 labeled, ?volume?) for gain adjustment. gain settings for both channels are tracked and controlled by the volume control ic (u_2) setting the gain from the microcontroller ic (u_1). the maximum volume setting (clockwise rotation) corresponds to a total gain of +37.9 db (78.8 v/v). the total gain is a product of the power-stage gain, which is constant (+23.2 db), and the input-stage gain that is directly-controlled by the volume adjustment. the volume range is about 100 db with minimum volume setting to mute the system with an overall gain of less than - 60 db. for best performance in testing, the internal volume control should be set to a gain of 21.9 v/v, or 1 vrms input will result in rated output power (120 w into 4 ), allowing for a >11 db overdrive. output filter design, preamplifier and performance the audio performance of the iraudamp4 depends on a number of different factors. the section entitled, ?typical performance? presents performance measurements based on the overall system, including the pr eamp and output filter. while the preamp and output filter are not part of the class d power stage, they have a significant effect on the overall performance. output filter since the output filter is not included in the control loop of the iraudamp4, the reference design cannot compensate for performance deterioration due to the output filter. therefore, it is there important to understand what characteristics are preferable when designing the output filter: 1) the dc resistance of the inductor should me minimized to 20 m or less. 2) the linearity of the output inductor and capacitor should be high with respect to load current and voltage. preamplifier the preamp allows partial gain of the input signal, and in the iraudamp4, controls the volume. the preamp itself will add distortion and noise to the input signal, resulting in a gain through the class d output stage and appearing at the output. even a few micro- volts of noise can add significantly to the output noise of the overall amplifier. in fact, the output noise from the preamp contributes more than half of the overall noise to the system. it is possible to evaluate the performance wi thout the preamp and volume control, by moving resistors r13 and r14 to r71 and r72, respectively. this effectively bypasses the preamp and connects the rca inputs directly to the class d power stage input. improving the selection of preamp and/or outpu t filter, will improve the overall system performance to approach that of the stand-alone class d power stage. in the ?typical
www.irf.com 7 rd-0617 performance? section, only limited data for the stand-alone class d power stage is given. for example, results for thd+n vs. output power are provided, utilizing a range of different inductors. by changing the inductor and repeating this test, a designer can quickly evaluate a particular inductor. figure 4. results of thd+n vs. output power with different output inductors self-oscillating pwm modulator the iraudamp4 class d audio power amplifie r features a self-oscillating type pwm modulator for the lowest component count and robust design. this topology represents an analog version of a second-order sigma-delta modulation having a class d switching stage inside the loop. the benefit of the sigma-delta modulation, in comparison to the carrier-signal based modulation, is that all the error in the audible frequency range is shifted to the inaudible upper-frequency range by nature of its operation. also, sigma- delta modulation allows a designer to apply a sufficient amount of correction. the self-oscillating frequency is determined by the total delay time inside the control loop of the system. the delay of the logic circuits, the IRS20955 gate-driver propagation delay, the irf6645 switching speed, the time-constant of front-end integrator (e.g. r25 + r29p, c11 and c13 for ch1) and variations in the supply voltages are critical factors of the self-oscillating frequency. under nominal conditions, the switching-frequency is around 400 khz with no audio input signal and a +/-35 v supply. adjustments of self-oscillating frequency the pwm switching frequency in this type of self-oscillating switching scheme greatly impacts the audio performance, both in absolute frequency and frequency relative to the other channels. in absolute terms, at higher frequencies, distortion due to switching-time becomes significant, while at lower frequencies, the bandwidth of the amplifier suffers. in relative terms, interference between channels is most significant if the relative frequency difference is within the audible range. normally when adjusting the self-oscillating frequency of the different channels, it is best to either match the frequencies accurately, 0.0001 100 0.001 0.01 0.1 1 10 % 100m 200m 500m 1 2 5 10 20 50 100 200 w t t t t t t t t t
www.irf.com 8 rd-0617 or have them separated by at least 25 khz. wi th the installed components, it is possible to change the self-oscillating frequency from about 160 khz up to 600 khz. potentiometers for adjustin g self-oscillating frequency r29p switching frequency for ch1* r30p switching frequency for ch2* *adjustments have to be done at an idling condition with no signal input. switches and indicators there are three different indicators on the reference design: ? an orange led, signifying a fault / shutdown condition when lit. ? a green led on the motherboard, signifying conditions are normal and no fault condition is present. ? a green led on the daughter board, signifying there is power. there are three switches on the reference design: ? switch s1 is a trip and reset push-button. pushing this button has the same effect of a fault condition. the circuit will restart about three seconds after the shutdown button is released. ? switch s2 is an internal clock-sync frequency selector. this feature allows the designer to modify the switching frequency in order to avoid am radio interference. with s3 is set to int, the two settings ?h? and ?l? will modify the internal clock frequency by about 20 khz to 40 khz, either higher ?h? or lower ?l.? the actual internal frequency is set by potentiometer r113 - ?int freq.? ? switch s3 is an oscillator selector. this three-position switch is selectable for internal self-oscillator (middle position ? ?self?), or either internal (?int?) or external (?ext?) clock synchronization. switching frequency lock / synchronization feature for single-channel operation, the use of the self-oscillating switching scheme will yield the best audio performance. the self-oscillating frequency, however, does change with the duty ratio. this varying frequency can interfere with am radio broadcasts, where a constant-switching frequency with its harmoni cs shifted away from the am carrier frequency, is preferred. in addition to am broadcasts, multiple channels can also reduce audio performance at low power, and can lead to increased residual noise. clock frequency locking/synchronization can address these unwanted characteristics. please note that the switching frequency lock / synchronization feature is not possible for all frequencies and duty ratios, and operates within a limited frequency and duty-ratio range around the self-oscillating frequency (figure 5).
www.irf.com 9 rd-0617 0 100 200 300 400 500 600 10% 20% 30% 40% 50% 60% 70% 80% 90% duty cycle operating frequency (khz) figure 5. typical lock frequency range vs. pwm duty ratio (self-oscillating frequency set to 400 khz with no input) as illustrated by the thd+n ratio vs. output power results (figure 6) , the noise levels increase slightly when all channels are driven (a cd) with the self oscillator, especially below the 5 w range. residual noise typically increases by a third or more (see ?specifications ? audio performance?) compared to a single-channel driven (scd) configuration. locking the oscillator frequency results in lowering the residual noise to that of a single-channel-driven system. the output power range, for which the frequency- locking is successful, depends on what the locking frequency is with respect to the self- oscillating frequency. as illustrated in figure 6, the locking frequency is lowered (from 450 khz to 400 khz to 350 khz and then 300 khz) as the output power range (where locking is achieved) is extended. once locki ng is lost, however, the audio performance degrades, but the increase in thd seems independent from the clock frequency. therefore, a 300 khz clock frequency is recommended. it is possible to improve the thd performance by increasing the corner frequency of the high pass filter (hpf) (r17 and c15 for ch1) that is used to inject the clock signal. this drop in thd, however, comes at the cost of reducing the locking range. resistor values of up to 100 k and capacitor values down to 10 pf can be used. in the iraudamp4, this switching frequency lock/synchronization feature is achieved with either an internal or external clock input (selectable through s3). if an internal (int) clock is selected, an internally-generated clock signal will be used, adjusted by setting potentiometer r113 ?int freq.? if external (ext) clock signal is selected, a 0 v to 5 v square-wave (~50% duty ratio) logic signal must be applied to bnc connector j17. locking range self-oscillating frequency suggested clock frequency for maximum locking range
www.irf.com 10 rd-0617 figure 6. thd+n ratio vs. output power for different switching frequency lock/synchronization conditions IRS20955 gate driver ic the iraudamp4 uses the IRS20955, which is a high-voltage (up to 200 v), high-speed power mosfet gate driver with internal deadtime and protection functions specifically designed for class d audio amplifier applications. these functions include ocp and uvp. a bi-directional current protection feature that protects both the high-side and low- side mosfets are internal to the IRS20955, and the trip levels for both mosfets can be set independently. in this design, the deadtime can be selected for optimized performance, by minimizing deadtime while limiting shoot-through. as a result, there is no gate-timing adjustment on the board. selectable deadtime through the dt pin voltage is an easy and reliable function which requires only two external resistors, r11 and r9. figure 7. system-level view of gate driver IRS20955 100 0.001 0.01 0.1 1 10 % 100m 200 200m 500m 1 2 5 10 20 50 100 power ( w ) self osc. (acd) int. clock @ 300 khz int. clock @ 450 khz self osc. (single channel driven) r11 r9
www.irf.com 11 rd-0617 selectable deadtime the IRS20955 determines its deadtime based on the voltage applied to the dt pin. an internal comparator translates which pre-determined deadtime is being used by comparing the dt voltage with internal reference voltages. a resistive voltage divider from v cc sets threshold voltages for each setting, negating the need for a precise absolute voltage to set the mode. the threshold voltages between deadtime settings are set internally, based on different ratios of v cc as indicated in the diagram below. in order to avoid drift from the input bias current of the dt pin, a bias current of greater than 0.5 ma is suggested for the external resistor divider circuit. suggested values of resistance that are used to set a deadtime are given below. resistors with up to 5% tolerance can be used. deadtime mode deadtime r11 r9 dt voltage dt1 ~15 ns <10k open v cc dt2 ~25 ns 5.6k 4.7k 0.46(v cc ) dt3 ~35 ns 8.2k 3.3k 0.29(v cc ) dt4 ~45 ns open <10k com figure 8. deadtime settings vs. v dt voltage over-current protection (ocp) in the iraudamp4, the IRS20955 gate driver accomplishes ocp internally, a feature discussed in greater detail in the ?protection? section. offset null (dc offset) the iraudamp4 is designed such that no output-offset nullification is required. dc offsets are tested to be less than 5 mv. bridged output the iraudamp4 is not intended for btl operation. however, btl operation can be achieved by feeding out-of-phase audio input signals to the two input channels. in btl operation, minimum load impedance is 8 ? and rated power is 240 w non-clipping. the installed clamping diodes d5 ? d8 are required for btl operation, since reactive energy flowing from one output to the other during clipping can force the output voltage beyond the voltage supply rails if not clamped. default
www.irf.com 12 rd-0617 startup and shutdown one of the most important aspects of any audio amplifier is the startup and shutdown procedures. typically, transients occurring duri ng these intervals can result in audible pop- or click-noise on the output speaker. traditionally, these transients have been kept away from the speaker through the use of a series relay that connects the speaker to the audio amplifier only after the startup transients have passed and disconnects the speaker prior to shutting down the amplifier. it is interesting to note that the audible noise of the relay opening and closing is not considered ?click noise?, although in some cases, it can be louder than the click noise of non-relay-based solutions. the iraudamp4 does not use any series relay to disconnect the speaker from the audible transient noise, but rather a shunt-based click noise reduction circuit that yields audible noise levels that are far less that those generated by the relays they replace. this results in a more reliable, superior performance system. for the startup and shutdown procedures, the activation (and deactivation) of the click- noise reduction circuit, the class d power stage and the audio input (mute) controls have to be sequenced correctly to achieve the required click noise reduction. the overall startup sequencing, shutdown sequencing and shunt circuit operation are described below. click-noise reduction circuit (solid-state shunt) to reduce the turn-on and turn-off click noise, a low impedance shunting circuit is used to minimize the voltage across the speaker during transients. for this purpose, the shunting circuit must include the following characteristics: 1) an impedance significantly lower than that of the speaker being shunted. in this case, the shunt impedance is ~100 m ? , compared to the nominal 4 ? speaker impedance. 2) when deactivated, the shunting circuit must be able to block voltage in both directions due to the bi-directional nature of the audio output. 3) the shunt circuit requires some form of ocp. if one of the class d output mosfets fails, or is conducting when the speaker mute (sp mute) is activated, the shunting circuit will effectively try to short one of the two supplies (+/-b). the implemented click-noise reduction circuit is shown in figure 9. before startup or shutdown of the class d power stage, the click-noise reduction circuit is activated through the sp mute control signal. with sp mute signal high, the speaker output is shorted through the back-to-back mosfets (u9 for channel 1) with an equivalent on resistance of about 100 m ? . the two transistors (u7 for channel 1) are for the ocp circuit.
www.irf.com 13 rd-0617 +b -b speaker mute figure 9. class d output stage with click-noise reduction circuit startup and shutdown sequencing the iraudamp4 sequencing is achieved through the charging and discharging of the cstart capacitor c117. this, coupled to the charging and discharging of the voltage of csd (c3 on daughter board for ch1) of the IRS20955, is all that is required for complete sequencing. the conceptual startup and shutdown timing diagrams are show in figure 10. figure 10. conceptual startup sequencing of power supplies and audio section timing v cc -b +b +5 v -5 v cstart csd uvp@-20 v csd= 2/3v dd cstart ref2 cstart ref1 a udio mute sp mute chx_o class d startup time music startup over current protection click noise reduction circuit transient current p aths
www.irf.com 14 rd-0617 for startup sequencing, +/-b supplies startup at different intervals. as +/-b supplies reach +5 v and -5 v respectively, the analog supplies (+/-5 v) start charging and, once +b reaches ~16 v, v cc charges. once ?b reaches -20 v, the uvp is released and csd and cstart start charging. once +/-5 v is established, the click-noise reduction circuit is activated through the sp mute control signal. as csd reaches two-thirds v dd , the class d stage starts oscillating. once the startup transient has passed, sp mute is released (cstart reaches ref1). the class d amplifier is now operational, but the preamp output remains muted until cstart reaches ref2. at this point, normal operation begins. the entire process takes less than three seconds. figure 11. conceptual shutdown sequencing of power supplies and audio section timing shutdown sequencing is initiated once uvp is activated. as long as the supplies do not discharge too quickly, the shutdown sequence can be completed before the IRS20955 trips uvp. once uvp is activated, csd and cstart are discharged at different rates. in this case, threshold ref2 is reached first and the preamp audio output is muted. once cstart reaches threshold ref1, the click-noise reduction circuit is activated (sp mute). it is then possible to shutdown the class d stage (csd reaches two-thirds v dd ). this process takes less than 200 ms. v cc -b +b +5 v -5 v cstart csd uvp@-20 v csd= 2/3v dd cstart ref1 cstart ref2 a udio mute sp mute chx_o class d shutdown time music shutdown
www.irf.com 15 rd-0617 for any external fault condition (otp, ovp, uvp or dcp ? see ?protection?) that does not lead to power supply shutdown, the system will trip in a similar manner as described above. once the fault is cleared, the syst em will reset (similar sequence as startup). figure 12. conceptual click noise reduction sequencing at trip and reset cstart csd external trip csd= 2/3vdd cstart ref1 cstart ref2 sp mute chx_o a udio mute class d shutdown time music shutdown class d startup music startup cstart ref1 cstart ref2 reset
www.irf.com 16 rd-0617 protection the iraudamp4 has a number of protection circuits to safeguard the system and speaker during operation, which fall into one of two categories, internal faults and external faults, and distinguished by the manner in which a fault condition is treated. internal faults are only relevant to the particular channel, while external faults affect the whole board. for internal faults, only the offending channel is stopped. the channel will hiccup until the fault is cleared. for exter nal faults, the whole board is stopped using the shutdown sequencing described earlier. here, the system will also hiccup until the fault is cleared at which time it will restart according to the startup sequencing described earlier. 20955 pwm ocp ovp/ uvp dcp red led -b +b trip -b vcc otp green led to other channel csd figure 13. functional block diagram of protection circuit implementation internal faults ocp and otp are considered internal faults. these internal faults will only shutdown the particular channel by pulling low the relevant csd pin. the channel will shutdown for about one-half a second and will hiccup until the fault is cleared. over-temperature protection (otp) a separate ptc resistor is placed in close proximity to the high-side irf6645 directfet mosfet for each of the amplifier channels. if the resistor temperature rises above 100 c, the otp is activated. the otp protection will only shutdown the relevant channel by pulling low the csd pin and will recover once the temperature at the ptc has dropped sufficiently. this temperature protection limit yields a pcb temperature at the mosfet of about 100 c. this setting is limited by the pcb material and not by the operating range of the mosfet. over-current protection (ocp) the ocp internal to the IRS20955 shuts down the ic if an ocp is sensed in either of the output mosfets. for a complete description of the ocp circuitry, please refer to the IRS20955 datasheet. here is a brief description:
www.irf.com 17 rd-0617 low-side current sensing the low-side mosfet is protected from an overload condition and will shutdown the switching operation if the load current exceeds a preset trip level. the low-side current sensing is based on measurement of mosfet drain-to-source voltage during the low- side mosfet on state. the voltage set on the ocset pin programs the threshold for low-side over-current sensing. thus, if the v s voltage (during low-side conduction) is higher than the ocset voltage, the IRS20955 will trip. it is recommended to use vref to supply a reference voltage to a resistive divider (r5 and r7 for ch1) generating a voltage to ocset for better variability against v cc fluctuations. for iraudamp4, the low-side over-current trip level is set to 0.65 v. for the irf6645 directfet mosfets with a nominal r ds-on of 28 m ? at 25 c, this results in a ~23 a maximum trip level. since the r ds-on is a function of temperature, the trip level is reduced to ~15 a at 100 c. figure 14. simplified functional block diagram of low-side current sensing (ch1) high-side current sensing the high-side mosfet is protected from an overload condition and will shutdown the switching operation if the load current exceeds a preset trip level. high-side over-current sensing monitors detect an overload condition by measuring drain-to-source voltage (v ds ) through the csh and vs pins. the csh pin detects the drain voltage with reference to the vs pin, which is the source of the high-side mosfet. in contrast to the low-side current sensing, the threshold of csh pin to engage oc protection is internally fixed at 1.2 v. an external resistive di vider r23 and r25 (for ch1) can be used to program a higher threshold. an additional external reverse blocking diode (d5 for ch1) is required to block high-voltage feeding into the csh pin during low-side conduction. by subtracting a forward voltage drop of 0.6 v at d5, the minimum threshold which can be set in the high-side is 0.6 v across the drain-to-source. for iraudamp4, the high-side over-current trip level is set to 0.6 v across the high-side mosfet. for the irf6645 mosfets with a nominal r ds-on of 28 m ? at 25 c, this results in a ~21 a maximum trip level. since the r ds-on is a function of temperature, the trip level is reduced to ~14 a at 100 c.
www.irf.com 18 rd-0617 figure 15. simplified functional block diagram of high-side current sensing (ch1) for a complete description of calculating and designing the over-current trip limits, please refer to the IRS20955 datasheet. external faults ovp, uvp and dcp are considered external faul ts. in the event that any external fault condition is detected, the shutdown circuit will activate for about three seconds, during which time the orange ?protection? led will turn on. if the fault condition has not cleared, the protection circuit will hiccup until fault is removed. once the fault is cleared, the green ?normal? led will turn on. there is no manual reset option. over-voltage protection (ovp) ovp will shutdown the amplifier if the bus voltage between gnd and -b exceeds 40 v. the threshold is determined by the voltages sum of the zener diode z105, r140, and v be of q109. as a result, it protects the board from bus pumping at very low audio signal frequencies by shutting down the amplifier. ovp will automatically reset after three seconds. since the +b and ?b supplies are as sumed to be symmetrical (bus pumping, although asymmetrical in time, will pump the bus symmetrically in voltage level). it is sufficient to sense one of the two supply voltages only for ovp. it is therefore up to the user to ensure that the power supplies are symmetrical.
www.irf.com 19 rd-0617 under-voltage protection (uvp) uvp will shutdown the amplifier if the bus voltage between gnd and -b falls below 20 v. the threshold is determined by the voltages sum of the zener diode z107, r145 and v be of q110. same as ovp, uvp will automatically reset after three seconds and only one of the two supply voltages is monitored. speaker dc-voltage protection (dcp) dcp is provided to protect against dc current flowing into the speakers. this abnormal condition is rare and is likely caused when the power amplifier fails and one of the high- side or low-side irf6645 directfet mosfets remain in the on state. dcp is activated if either of the outputs has more than 4 v dc offset (typical). under this fault condition, it is normally required to shutdown the feeding power supplies. since these are external to the reference design board, an isolated relay is provided (p1) for further systematic evaluation of dc-voltage protection to transmit this condition to the power supply controller and is accessible through connector j9 (pins of j9 are shorted during fault condition).
www.irf.com 20 rd-0617 thermal considerations the daughter board design can handle one-eighth of the continuous rated power, which is generally considered to be a normal operating condition for safety standards. without the addition of a heatsink or forced air-cooling, the daughter board cannot handle continuous rated power. 0.0% 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% 70.0% 80.0% 90.0% 100.0% 0 20 40 60 80 100 120 140 160 180 output power (w) power stage efficiency (%) figure 16. efficiency fv. output power, 4 single channel driven, b supply = 35 v, 1 khz audio signal figure 17. thermal image of daughter board two-channel x 1/8th rated power (15 w) in operation, t c = 54 c at steady state b supply = 35 v, 4 load, 1 khz audio signal, t a = 25 c 54 c 67 c
www.irf.com 21 rd-0617 typical performance b supply = 35 v, load impedance = 4 , 1 khz audio signal, self oscillator @ 400 khz and internal volume-control set to give required output with 1 vrms input signal, unless otherwise noted. green ch1 - 4 ? , 2 v output red ch1 - 8 ? , 2 v output figure 18. frequency characteristics vs. load impedance red ch2 ? ch1, 60 w, self oscillator @ 400 khz green ch2 ? ch1, 60 w, internal clock @ 300 khz figure 19. channel separation vs. frequency hz -120 +0 -100 -80 -60 -40 -20 d b 20 20k 50 100 200 500 1k 2k 5k 10k self int. hz 4 8 -10 +4 -8 -6 -4 -2 +0 +2 d b r a 20 200k 50 100 200 500 1k 2k 5k 10k 20k 50k
www.irf.com 22 rd-0617 red ch2 ? ch1, 60 w, self oscillator @ 400 khz green ch2 ? ch1, 60 w, internal clock @ 300 khz figure 20. stand-alone class d power stage: channel separation vs. frequency green ch1 - acd, b = 35 v, vo lume gain 21.9 v/v ? aux-25 filter red ch1 - acd, b = 35 v, volume gain 21.9 v/v ? 3 rd order rc filter figure 21. stand-alone class d power stage: thd+n ratio vs. output power -120 +0 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 d b 20 20k 50 100 200 500 1k 2k 5k 10k hz self int. 0.0001 100 0.001 0.01 0.1 1 10 50 % 100m 200 200m 500m 1 2 5 10 20 50 100 w
www.irf.com 23 rd-0617 green ch1, b = 35 v, volume gain 21.9 v/v blue ch1, b = 30 v, volume gain 21.9 v/v red ch1, b = 25 v, volume gain 21.9 v/v figure 22. thd+n ratio vs. output power green ch1 - acd, b = 35 v, volume gain 21.9 v/v blue ch1 - acd, b = 30 v, volume gain 21.9 v/v red ch1 - acd, b = 25 v, volume gain 21.9 v/v figure 23. thd+n ratio vs. output power (acd) 0.001 100 0.002 0.01 0.02 0.1 0.2 0.5 1 5 10 50 % 100m 200 200m 500m 1 2 5 10 20 50 100 w 25 v 35 v 30 v 0.001 100 0.01 0.1 1 10 % 100m 200 200m 500m 1 2 5 10 20 50 100 w t 25 v 35 v 30 v
www.irf.com 24 rd-0617 green ch1, 1 w output blue ch1, 10 w output red ch1, 100 w output figure 24. thd+n ratio vs. frequency green ch1 - acd, 1 w output yellow ch1 - acd, 10 w output red ch1 - acd, 100 w output figure 25. thd+n ratio vs. frequency (acd) hz 0.0001 100 0.001 0.01 0.1 1 10 % 20 20k 50 100 200 500 1k 2k 5k 10k 10 w 1w 100 w 0.0001 100 0.001 0.01 0.1 1 10 % 20 20k 50 100 200 500 1k 2k 5k 10k hz 10 w 1w 100 w
www.irf.com 25 rd-0617 green ch1 - acd, 1 v, 1 khz, self oscillator @ 400 khz red ch1 - acd, 1 v, 1 khz, internal clock @ 300 khz figure 26. frequency spectrum (acd) green ch1 - acd, no signal, self oscillator @ 400 khz red ch1 - acd, no signal, internal clock @ 300 khz figure 27. residual noise (acd) hz -140 +0 -120 -100 -80 -60 -40 -20 d b v 10 20k 20 50 100 200 500 1k 2k 5k 10k se lf int. -140 +0 -120 -100 -80 -60 -40 -20 d b v 10 20k 20 50 100 200 500 1k 2k 5k 10k hz self int.
www.irf.com 26 rd-0617 60 w / 4 , 1 khz, thd+n=0.004% 174 w / 4 , 1 khz, thd+n=10% figure 28. measured output and distortion waveforms figure 29. typical ocp waveforms showing load current and switch node voltage (v s ) figure 30. typical ocp waveforms showing csd trip and hiccup load current csd p in load current vs p in csd p in vs p in load current csd p in vs p in load current csd p in vs p in red trace: total distortion + noise voltage green trace: output voltage
www.irf.com 27 rd-0617 iraudamp4 design documents motherboard schematics: c105 10uf, 50v protection z102 4.7v r104 47r, 1w r105 10r c106 10uf, 50v r124 10k r121 47k r122 47k vin gnd vout u_6 mc78m12 ch1 o ch2 o q106 mmbt5401 q104 mmbt5401 z103 15v c103 10uf, 50v in gnd out u_5 mc79m05 c102 10uf, 50v r102 47r, 1w c101 10uf, 50v vin gnd vout u_4 mc78m05 z101 4.7v c116 100uf, 16v r141 47k normal hs1 r123 1k q102 mmbt5401 r107 4.7k r106 47k z104 24v q101 fx941 d102 ma2yd2300 d101 ma2yd2300 c104 10uf, 50v q108 mmbt5551 s1 sw-pb vss 8 vr0 7 vr1 6 clk 5 vdd 1 cs 2 sdata 3 simul 4 u_2 3310s06s r108 ct2265 c107 4.7uf, 16v c108 10nf, 50v c109 4.7uf, 16v cs sdatai sclk mute heat sink 294-1086-nd 1 2 3 6 5 4 p1 pvt412 1 2 j9 ed1567 dc_ps r101 47r, 1w r103 47r, 1w +5v -b vcc +b -5v +5v cs sdatai sclk mute vcc -b -5v +5v +b gnd q105 mmbt5551 r125 10k r126 100k +b q109 mmbt5551 r139 47k -b sd d105 1n4148 r138 4.7k +b -b z106 18v z107 18v r145 47k r146 47k q110 mmbt5551 r144 10k d107 1n4148 d106 1n4148 c117 100uf, 16v +5v r142 68k +5v r119 1k r136 68k r135 82k 1a 1y 2a 2y 3a 3y gnd vcc 6a 6y 5a 5y 4a 4y u_3 74hc14 r120 100r c114 10nf, 50v +5v i e s sw s3a sw-3way_a-b r109 1k r110 100k c110 1nf, 50v c112 1200pf, 50v d103 1n4148 clk r116 47r clk i e s sw s3b sw-3way_a-b ext. clk a24497 j8 bnc r115 47r r114 100r r113 5k pot r112 820r c111 100pf, 50v q103 mmbt5551 2 1 s2 sw_h-l r111 10k c113 100pf, 50v r134 10k r117 47r r143 10k sp mute r118 1k r129 6.8k c115 10uf, 50v -b r140 10k z105 39v dc protection ovp r132 47k q107 mmbt5551 d104 1n4148 r133 47k dcp dcp r127 6.8k r128 6.8k r130 47k r131 47k r148 10k r147 47k q111 mmbt5401 +b earth r149 47k c119 0.1uf, 50v uvp iraudamp ver.4 - power supply and protection z108 8.2v r137 47k -5v ot ot cstart q112 mmbt5551 -5v +5v z109 8.2v r150 47k r151 47k +b r152 open figure 31. housekeeping and protection circuits
www.irf.com 28 rd-0617 j5 1418-nd r5 4.7r r13 3.3k c11 1nf, 200v c13 1nf, 200v r25 100r r29p 1k c9 3.3uf, 50v c23_1 open 1 2 j3 277-1022 l1 22uh r31 47k r58 100k r35 1k r23 4.7r r21 4.7r c7 3.3uf, 50v r37 1k j6 1418-nd r4 100r r14 3.3k d2 1n4148 d4 1n4148 c12 1nf, 200v c14 1nf, 200v r26 100r r30p 1k c10 3.3uf, 50v r32 47k r36 1k r24 4.7r r22 4.7r c8 3.3uf, 50v r38 1k c32 1000uf,50v c31 1000uf,50v r57 100k c27 open c24_1 open c26 0.1uf, 400v c28 open l2 22uh u1 tlc081 u2 tlc081 +b -b r48 10, 1w d1 1n4148 d3 1n4148 r34 1k r33 1k c18 150pf, 500v c17 150pf, 500v ch1 out ch2 out ch2 in ch1 in 1 2 j4 277-1022 c33 open c34 open r39 470r r40 470r r49 2.2k zcen cs sdatai vd+ dgrd sclk sdatao mute ainl agndr aoutl va- va+ aoutr agndl ainr u_1 cs3310 r3 100r r1 100k c2 2.2uf, 50v c3 2.2uf, 50v r2 100k r6 4.7r r7 47r r8 47r r9 10r r10 47r r11 47r c1 10uf, 50v r50 2.2k r17 22k r18 22k c16 33pf clk cs sdatai sclk mute c25 0.1uf, 400v r47 10, 1w ch2 o c15 33pf u3 74ahc1g04 u4 74ahc1g04 c19 2.2uf, 16v c20 2.2uf, 16v r27 47r r28 47r c23 0.47uf, 630v c24 0.47uf,630v r29 open r30 open c44 open r64 open -b 6 +b 15 gnd 16 -b 7 ch1 o 9 ch2 o 1 ch2 o 2 ch1 o 10 -b 5 ch2o 3 ch2 o 4 -b 8 ch1 o 11 ch1 o 12 +b 14 +b 13 j2 vcc sd gnd -5v +5v +5v +5v c5 10uf, 50v c6 10uf, 50v -5v -5v +5v +5v +5v in2 12 pwm1 3 vss 2 vcc 10 sd 11 ot 1 vss 8 pwm2 7 gnd1 5 in1 4 vaa 6 gnd2 9 j1 con eisa31 +5v -5v -5v ch1 o ch2 o -5v +5v z2 15v c30 open sp mute d12 1n4148 d11 1n4148 c29 open z1 15v r20 0r r19 0r r56 open r55 open r53 47k r51 100k r54 47k r52 100k clk clk 1 8 2 3 5 4 6 7 u9 irf7341 1 8 2 3 5 4 6 7 u10 irf7341 1 2 3 j7 277-1272 d5 mura120t3osct-nd d7 mura120t3osct-nd d8 mura120t3osct-nd d6 mura120t3osct-nd -b +b -b +b -b +b ch1 o cs sdatai sd sp mute sp mute earth c43 open r63 open c41 open r61 open c46 open r66 open c42 open r62 open c48 open r68 open c45 open r65 open c47 open r67 open c49 open r69 open c40 open r60 open iraudamp ver.4 - preamp and power stage ot 5 1 3 2 4 u7 xn01215 5 1 3 2 4 u8 xn01215 r72 open r71 open figure 32. audio channels 1 and 2
www.irf.com 29 rd-0617 daughter board schematics: d1 1n4148 r1 100r r3 10k r11 3.3k q3 irf6645 q5 irf6645 r9 8.2k r7 1.2k d3 mura120t3osct-nd vcc 11 vs 13 ho 14 nc 12 csd 2 vdd 1 lo 10 com 9 dt 8 in 3 vss 4 nc 5 vref 6 oc 7 vb 15 csh 16 u1 IRS20955s r13 4.7r r29 10r r27 10r r15 10r r16 10r c1 2.2uf, 25v c7 22uf, 25v r25 10k r23 0r r21 10k c11 47pf c3 10uf, 16v r19 47k +b ch1 o -b pwm 1 vcc ds1 160-1414-1-nd r43 4.7k r5 8.2k d5 bav19wdict-nd vss1 d2 1n4148 r2 100r r4 10k r12 3.3k q4 irf6645 q6 irf6645 r10 8.2k r8 1.2k d4 mura120t3osct-nd vcc 11 vs 13 ho 14 nc 12 csd 2 vdd 1 lo 10 com 9 dt 8 in 3 vss 4 nc 5 vref 6 oc 7 vb 15 csh 16 u2 IRS20955s r14 4.7r r30 10r r28 10r c2 2.2uf, 25v c8 22uf, 25v r26 10k r24 0r r22 10k c12 47pf c4 10uf, 16v r20 47k ch2 o sd pwm 2 r6 8.2k d6 bav19wdict-nd vss2 c5 open c6 open c22 47nf r40 100k r37 100k rp1 100c r34 1k r36 100k q7 mmbt3904 q2 mmbt5401 rp2 100c r38 100k r41 10k c21 47nf r33 1k r35 100k q1 mmbt5401 r39 100k c23 47nf otp ch2 otp ch1 c17 0.1uf,100v c18 0.1uf,100v c13 0.1uf r31 1r c14 0.1uf r32 1r tp2 tp1 d7 s1db-fdict-nd in2 12 pwm1 3 vss 2 vcc 10 sd 11 ot 1 vss 8 pwm2 7 gnd1 5 in1 4 vaa 6 gnd2 9 j1 con eisa31 pwm 1 vss1 sd vss2 vcc -b +b ch1 o ch2 o -b 6 +b 15 gnd 16 -b 7 ch1 o 9 ch2 o 1 ch2 o 2 ch1 o 10 -b 5 ch2o 3 ch2 o 4 -b 8 ch1 o 11 ch1 o 12 +b 14 +b 13 j2 vcc sd +b -b pwm 2 c10 2.2uf, 25v c9 2.2uf, 25v +b -b c15 0.1uf,100v c16 0.1uf,100v vss2 vss1 q8 mmbt3904 r42 10k c24 47nf csd2 csd1 csd1 csd2 +b iraudamp ver.4 - daughter board d8 ma2yd2300 d9 ma2yd2300 figure 33. daughter board schematic with class d stag e for two audio channels
www.irf.com 30 rd-0617 iraudamp4 bill of materials motherboard: iraudamp4 motherboard bill of material no designator # footprint parttype part no vender 1 c1, c5, c6, c101, c102, c103, c104, c105, c106, c115 10 rb2/5 10uf, 50v 565-1106-nd digikey 2 c2, c3 2 rb2/5 2.2uf, 50v 565-1103-nd digikey 3 c7, c8, c9, c10 4 cr3225-1210 3.3uf, 50v 445-1432-1-nd digikey 4 c11, c12, c13, c14 4 1206 1nf, 200v pcc2009ct-nd digikey 5 c15, c16 2 805 33pf 478-1281-1-nd digikey 6 c17, c18 2 axial0.19r 150pf, 500v 338-1052-nd digikey 7 c19, c20 2 1206 2.2uf, 16v pcc1931ct-nd digikey 8 c119 1 1206 0.1uf, 50v pcc104bct-nd digikey 9 c23, c24 2 cap mkp 0.47uf, 630v 495-1315-nd digikey 10 c23_1, c24_1 2 axial0.2r open - digikey 11 c25, c26 2 cap mkps 0.1uf, 400v 495-1311-nd digikey 12 c27, c28, c29, c30, c40, c41, c42, c43, c44, c45, c46, c47 1 2 805 open - digikey 13 r29, r30, r55, r56, r60, r61, r62, r63, r64, r65, r66, r67, r71, r72 1 4 805 open - digikey 14 c31, c32 2 rb5/12_5 1000uf,50v 565-1114-nd digikey 15 c33, c34, c48, c49 4 axial0.1r open - digikey 16 c107, c109 2 805 4.7uf, 16v pcc2323ct-nd digikey 17 c108, c114 2 805 10nf, 50 v pcc103bnct-nd digikey 18 c110 1 805 1nf, 50v pcc102cgct-nd digikey 19 c111, c113 2 805 100pf, 50v pcc101cgct-nd digikey 20 c112 1 805 1200pf, 50v 478-1372-1-nd digikey 21 c116, c117 2 rb2/5 100uf, 16v 565-1037-nd digikey 22 d1, d2, d3, d4, d11, d12, d103, d104, d105, d106, d107 1 1 sod-123 1n4148 1n4148wdict-nd digikey 23 d5, d6, d7, d8 4 sma mura120 mura120t3osct-nd digikey 24 d101, d102 2 sod-123 ma2yd2300 ma2yd2300lct-nd digikey 25 hs1 1 heat_s6in1 heat sink 294-1086-nd digikey 26 j1a, j1b 2 con eisa-31 con eisa31 a26453-nd digikey 27 j2a, j2b 2 con_power con_power a26454-nd digikey 28 j3, j4 2 mkds5/2-9.5 277-1022 277-1271-nd or 651- 1714971 digikey or mouser 29 j5, j6 2 cp1418 1418-nd cp-1418-nd digikey 30 j7 1 j header3 277-1272 277-1272-nd or 651- 1714984 digikey or mouser 31 j8 1 bnc_ra con bnc a32248-nd digikey 32 j9 1 ed1567 ed1567 ed1567 digikey 33 l1, l2 2 inductor 22uh 'sagami 7g17a-220m- r or in09063 'inductor s, inc. or ice compon ents, inc. 34 normal 1 led rb2/5 404-1106-nd 160-1143-nd digikey 35 p1 1 dip-6 pvt412 pvt412-nd digikey 36 protection 1 led rb2/5 404-1109-nd 160-1140-nd digikey 37 q101 1 sot89 fx941 fcx491ct-nd digikey 38 q102, q104, q106, q111 4 sot23-bce mmbt5401 mmbt5401dict-nd digikey 39 q103, q105, q107, q108, q109, q110, q112 7 sot23-bce mmbt5551 mmbt5551-7dict-nd digikey 40 r1, r2, r51, r52, r57, r58, r110, r126 8 805 100k p100kact-nd digikey 41 r3, r4, r114 3 805 100r p100act-nd digikey 42 r5, r6 2 1206 4.7r p4.7ect-nd digikey 43 r7, r8, r10, r11, r27, r28, r115, r116, r117 9 805 47r p47act-nd digikey 44 r9, r105 2 805 10r p10act-nd digikey 45 r13, r14 2 805 3.3k, 1% p3.3kzct-nd digikey 46 r17, r18 2 805 22k p22kact-nd digikey 47 r53, r54, r106, r121, r122, r130, r131, r132, r133, r137, r139, r141, r145, r146, r147, r149, r150, r151 1 8 805 47k p47kact-nd digikey 48 r152 1 805 open - digikey 49 r19, r20 2 805 0r p0.0act-nd digikey 50 r39, r40 2 805 470r p470act-nd digikey 51 r21, r22, r23, r24 4 805 4.7r p4.7act-nd digikey
www.irf.com 31 rd-0617 52 r25, r26, r120 3 1206 100r p100ect-nd digikey 53 r29p, r30p 2 pot_srm 1k 3361p-102gct-nd digikey 54 r31, r32 2 2512 47k, 1% pt47kafct-nd digikey 55 r33, r34 2 1206 1k p1.0kect-nd digikey 56 r35, r36, r37, r38, r109, r118, r119, r123 8 805 1k p1.0kact-nd digikey 57 r47, r48 2 2512 10, 1w pt10xct digikey 58 r49, r50 2 1206 2.2k p2.2kect-nd digikey 59 r68, r69 2 axial-0.3 open - digikey 60 r101, r102, r103, r104 4 2512 47r, 1w pt47xct-nd digikey 61 r107, r138 2 805 4.7k p4.7kact-nd digikey 62 r108 1 v_control ct2265 ct2265-nd digikey 63 r111, r124, r125, r134, r140, r143, r144, r148 8 805 10k p10kact-nd digikey 64 r112 1 805 820r p820act-nd digikey 65 r113 1 pots 5k pot 3362h-502-nd digikey 66 r127, r128, r129 3 1206 6.8k p6.8kect-nd digikey 67 r135 1 805 82k p82kact-nd digikey 68 r136, r142 2 805 68k p68kact-nd digikey 69 s1 1 switch sw-pb p8010s-nd digikey 70 s2 1 sw-eg1908-nd sw_h-l eg1908-nd digikey 71 s3 1 sw-eg1944-nd sw-3way eg1944-nd digikey 72 u1, u2 2 so-8 tlc081 296-7264-1-nd digikey 73 u3, u4 2 sot25 74ahc1g04 296-1089-1-nd digikey 74 u7, u8 2 mini5 xn01215 xn0121500lct-nd digike y 75 u9, u10 2 so-8 irf7341 irf7341 ir 76 u_1 1 soic16 cs3310 73c8016 or 72j5420 newark 77 u_2 1 n8a 3310s06s 3310-ir01 *tachyon ix 78 u_3 1 m14a 74hc14 296-1194-1-nd digikey 79 u_4 1 to-220 fullpak mc78m05 mc78m05btos-nd digikey 80 u_5 1 to-220 fullpak mc79m05 mc79m05ctos-nd digikey 81 u_6 1 to-220 fullpak mc78m12 mc78m12ctos-nd digikey 82 z1, z2, z103 3 sod-123 15v bzt52c15-fdict-nd digikey 83 z101, z102 2 sma 4.7v 1sma5917bt3gosct- nd digikey 84 z104 1 sod-123 24v bzt52c24-fdict-nd digikey 85 z105 1 sod-123 39v bzt52c39-13-fdict- nd digikey 86 z106, z107 2 sod-123 18v bzt52c18-fdict-nd digikey 87 z108, z109 2 sod-123 8.2v bzt52c8v2-fdict-nd digikey 88 volume knob 1 mccpmb1 newark 89 thermalloy to-220 mounting kit with screw 3 46f4081 newark 90 1/2" standoffs 4-40 5 8401k-nd digikey 91 4-40 nut 5 100 per bag h724-nd digikey 92 no. 4 lock washer 5 100 per bag h729-nd digikey *tachyonix corporation, 14 gonaka jimokuji jimokuji-cho, ama-gun aichi, japan 490-1111 http://www.tachyonix.co.jp info@tachyonix.co.jp
www.irf.com 32 rd-0617 voltage regulator mounting: daughter board: iraudamp4 dauther-boa rd bill of material no designator # footprint part type part no vendor 1 c1, c2, c9, c10 4 1206 2.2 f, 25 v 490-3368-1-nd digikey 2 c3, c4 2 t491 10 f, 16 v 399-3706-1-nd digikey 3 c5, c6 2 0805 open 4 c7, c8 2 1812 22 f, 25 v 445-1607-1-nd digikey 5 c11, c12 2 0805 47 pf pcc470cgct-nd digikey 6 c13, c14 2 0805 0.1 f pcc1840ct-nd digikey 7 c15, c16, c17, c18 4 1206 0.1 f,100 v pcc2239ct-nd digikey 8 c21, c22, c23, c24 4 0805 47 nf pcc1836ct-nd digikey 9 d1, d2 2 sod-123 1n4148 1n4148wdict-nd digikey 10 d3, d4 2 sma mura120t3osct-nd mura120t3osct-nd digikey 11 d5, d6 2 sod-123 bav19wdict-nd bav19w-fdict-nd digikey 12 d7 1 smb s1db-fdict-nd rs1db-fdict-nd digikey 13 d8, d9 2 sod-123 ma2yd2300 ma2yd2300lct-nd digikey 14 ds1 1 led 160-1414-1-nd 160-1414-1-nd digikey 15 j1 1 con eisa-31 con eisa31 2011-03-nd digikey 16 j2 1 con_power con_power 2011-04-nd digikey 17 q1, q2 2 sot23-bce mmbt5401 mmbt5401dict-nd digikey 18 q3, q4, q5, q6 4 directfet mosfet6645 irf6645 irf6645 ir 19 q7, q8 2 sot23-bce mmbt3904 mmbt3904-fdict-nd digikey 20 r1, r2 2 0805 100 ? p100act-nd digikey 21 r3, r4, r25, r26 4 1206 10 k ? p10kect-nd digikey 22 r5, r6, r9, r10 4 0805 8.2 k ? p8.2kact-nd digikey 23 r7, r8 2 0805 1.2 k ? p1.2kact-nd digikey 24 r11, r12 2 0805 3.3 k ? p3.3kact-nd digikey 25 r13, r14 2 0805 4.7 ? p4.7act-nd digikey 26 r15, r16, r27, r28, r29, r30 6 0805 10 ? p10act-nd digikey 27 r19, r20 2 0805 33 k ? p33kact-nd digikey 28 r21, r22, r41, r42 4 0805 10 k ? p10kact-nd digikey 29 r23, r24 2 0805 0 ? p0.0act-nd digikey 30 r31, r32 2 0805 1 ? p1.0act-nd digikey 31 r33, r34 2 0805 1 k ? p1.0kact-nd digikey 32 r35, r36, r37, r38, r39, r40 6 0805 100 k ? p100kact-nd digikey 33 r43 1 0805 4.7 k ? p4.7kact-nd digikey 34 rp1, rp2 2 0805 100 c 594-2322-675-21007 mouser 35 u1, u2 2 m16a IRS20955spbf IRS20955spbf ir item description 1 insulator thermalfilm 2 shoulder washer 3 flat washer #4 4 no. 4-40 unc-2b hex nut 5 no. 4-40 unc-2a x 1/2 long phillips pan head screw 6 lockwasher, no.4 7 heatsink 8 pcb 7 8
www.irf.com 33 rd-0617 iraudamp4 pcb specifications figure 34. motherboard and daughter board layer stack motherboard: material: fr4, ul 125 c layer stack: 2 layers, 1 oz. cu dimensions: 5.2 in x 5.8 in x 0.062 in solder mask: lpi solder mask, smobc on top and bottom layers plating: open copper solder finish silkscreen: on top and bottom layers daughter board: material: fr4, ul 125 c layer stack: 2 layers, 1 oz. cu each, through-hole plated dimensions: 3.125 in x 1.52 in x 0.062 in solder mask: lpi solder mask, smobc on top and bottom layers plating: open copper solder finish silkscreen: on top and bottom layers
www.irf.com 34 rd-0617 iraudamp4 pcb layers motherboard: figure 35. top layer and pads
www.irf.com 35 rd-0617 figure 36. top-side solder-mask and silkscreen 4.0
www.irf.com 36 rd-0617 figure 37. bottom layer and pads
www.irf.com 37 rd-0617 figure 38. bottom-side solder-mask and silkscreen
www.irf.com 38 rd-0617 daughter board: figure 39. pcb layout ? top layer and pads figure 40. pcb layout ? top-side solder-mask and silkscreen
www.irf.com 39 rd-0617 figure 41. pcb layout ? bottom layer and pads figure 42. pcb layout ? bottom-side solder-mask and silkscreen
www.irf.com 40 rd-0617 iraudamp4 mechanical construction motherboard figure 43. top side of motherboard showing component locations
www.irf.com 41 rd-0617 figure 44. bottom side of motherboard showing component locations
www.irf.com 42 rd-0617 daughter board figure 45. top side showing component locations figure 46. bottom side showing connector locations 03/28/2007
www.irf.com 43 rd-0617 revisions history date done by description 3-28-07 jc - add caution note - modify the order of pcb layer figures - modify revision name and remove ir logo in daughterboard pcb - modify motherboard pcb to add components, change value and p/n of some components, remove ir logo and update revision name. details of changes: 1. change value of c19, c20, r39, and r40 2. change p/n of z101 and z102 3. add q112, r150, r151, r152, and z109 4. add lock washer to the bom 5. remove ir logo 6. update name as rev. 3 10-28-09 lz bom updated :ice components as a second vender of the inductor

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