LX1708 15+15W Stereo Filterless Class-D Amplifier ® TM P RODUCTION D ATA S HEET KEY FEATURES DESCRIPTION Filter Free Operation 12W +12W Output Power @ 4Ω load: THD+N < 1% High Efficiency > 85% Full Audio Bandwidth: 20Hz to 20kHz Low Distortion < 0.4% @ 30% Max Power, 1kHz High Signal-to-Noise Ratio: 90dB Wide Supply Voltage Range 5.0V ~ 15V 5mA Per Channel Typical Quiescent Current Turn ON/OFF POP Free Standby / Mute Feature Built-in Under Voltage Lockout Thermal Protection The part features on–board H-bridge output stages with low RDSON. External bootstrap capacitors are all that is required to provide the gate drive to the all-NFET output stage since on-board bootstrap diodes are provided. The LX1708 also features Mute and Standby modes, POP-free turn-on and turn-off, under-voltage lockout for both input supplies, and multi-level overtemperature protection. The LX1708 is offered in a small thermally efficient footprint, low profile surface mountable 32-pin Micro Lead Quad Package (MLPQ) in 7mm x 7mm. WWW . Microsemi .C OM The LX1708 is a fully integrated stereo class-D CMOS audio amplifier. optimized for highly efficient operation and minimum system cost. The stereo BTL (Bridge-tied-load) configuration uses 3-level PWM modulation. This allows eliminating the LC filter to reduce the system cost and simplify the system design. The LX1708 outputs 15W into each of two channels with better than 85% efficiency. The entire signal path from input to output is differential to reject any sources of common-mode noise or distortion. APPLICATIONS IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com LCD TV Car Navigation MP3 Docking Stations Portable Sound System PRODUCT HIGHLIGHT STBY 5V TMON ROSC V5V STBY N.C. STATUS AVSS1 PVSS1N OUT1N OUT2N BOOT2N BOOT1N PVDD1 PVDD PVDD1 LX1708 BOOT1P PVDD2 PVDD2 PVDD BOOT2P OUT1P MUTE N.C. TCTRL IN1P OUT2P VREF PVSS1P IN1N AVSS2 PVSS2N PVSS2P IN2P IN2N IN2P IN1P MUTE LX1708 IN2N IN1N PACKAGE ORDER INFO TA (°C) LQ Plastic MLPQ 32-Pin7mm x 7mm RoHS Compliant / Pb-free -40 to 85 LX1708ILQ Note: Available in Tape & Reel. Append the letters “TR” to the part number. (i.e. LX1708ILQ-TR) Copyright © 2007 Rev. 1.3, 2007-04-05 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 1 LX1708 TM ® 15+15W Stereo Filterless Class-D Amplifier P RODUCTION D ATA S HEET ABSOLUTE MAXIMUM RATINGS PACKAGE PIN OUT PVDD1 PVDD1 BOOT1N OUT1N PVSS1N 31 30 29 28 27 26 25 1 24 TCTRL IN1P 2 23 TMON IN1N 3 22 AVSS2 N.C. 4 21 ROSC N.C. 5 20 VREF IN2N 6 19 AVSS1 IN2P 7 18 V5V MUTE 8 17 STATUS MSC LX1708 XXXX 13 14 15 16 BOOT2N OUT2N PVSS2N OUT2P 12 PVDD2 PVSS2P 11 PVDD2 10 BOOT2P 9 WWW . Microsemi .C OM BOOT1P 32 STBY XXXX = date code / lot code THERMAL DATA OUT1P Note: Exceeding these ratings could cause damage to the device. All voltages are with respect to AVSS, except as noted. Currents are positive into, negative out of specified terminal. PVSS1P Power Supply Voltage (PVDD) ................................................................... -0.3V to 16.5V BOOTP/N - PVDD ......................................................................................... -0.3 to 16.5V Bias Supply Voltage (V5V) ................................................................................. -0.3 to 6V Input Pins (IN1P/N, IN2P/N ,TCTRL, STBY, MUTE) ......................-0.3V to V5V + 0.3V Output Pins (VREF, STATUS, ROSC, TMON) .................................-0.3V to V5V + 0.3V Maximum Operating Junction Temperature .............................................................. 150°C Storage Temperature Range.........................................................................-65°C to 150°C Package Peak Temp. for Solder Reflow (40 seconds maximum exposure) ... 260°C (+0 -5) LQ PACKAGE (Top View) LQ Plastic MLPQ 32-Pin 7mm x 7mm THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA Pb-free 100% Matte Tin Pin Finish 15.5°C/W Junction Temperature Calculation: TJ = TA + (PD x θJA). The θJA numbers are guidelines for the thermal performance of the device/pc-board system. All of the above assume no ambient airflow. PACKAGE DATA Copyright © 2007 Rev. 1.3, 2007-04-05 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 2 LX1708 ® TM 15+15W Stereo Filterless Class-D Amplifier P RODUCTION D ATA S HEET FUNCTIONAL PIN DESCRIPTION Function Pin Number(s) Description PVSS1P PVSS1N PVSS2P PVSS2N Power Ground 32 25 16 9 PVDD1 PVDD2 Power Supply 28,29 12,13 V5V Power Supply 18 Analog Power Supply for the analog signal processing section. AVSS1 AVSS2 Analog Ground 19 22 Analog Ground for the analog signal processing section. Must be at the same potential as PVSS, connect at one point to the power ground plane. IN1N IN1P IN2N IN2P Analog Input 3 2 6 7 Differential analog audio inputs for each channel. The common mode voltage will be set by the LX1708 to around 2.25V. OUT1N OUT1P OUT2N OUT2P Digital Output 26 31 15 10 Differential high power audio outputs for each channel. Each output will swing between PVDD and PVSS. These outputs are driven by an on-chip H-bridge output driver which uses low RDSON NFETs. BOOT1N BOOT1P BOOT2N BOOT2P Bootstrap 27 30 14 11 Bootstrap voltage pins which provide the high voltage needed to drive the upper NFET. A bootstrap capacitor should be placed between the respective output and these pins. VREF Analog Output 20 MUTE CMOS Input 8 Logic level control which mutes the audio signal when high. STBY CMOS Input 1 Logic level control which places the chip into sleep mode when high. STATUS CMOS Output 17 Digital monitoring pin which is used to flag internal fault states. This pin will be synchronized with the internal clock to prevent glitches. See the STATUS flag list (below) for a summary of which conditions will force this pin to go high. ROSC Analog Input 21 Frequency control pin. A resistor between this pin and AVSS will set the oscillation frequency for the Class-D modulator. Power Ground for the two H-bridge output drivers, connect to power ground plane Power Supply for the two H-bridge output drivers. Current draw will be up to 1.6A at 2 x 8W into 8Ω. These are peak currents when the part is run at maximum rated power on both channels. Typical 2.25V reference voltage which serves as an internal reference. An external compensation capacitor of at least 1uF should be connected between this pin and AVSS. Test Pin 24 Test purpose only, Connect to AVSS1 TMON Test Pin 23 Test purpose only, left open. N.C. No connect 4,5 No Connect, pin is open PACKAGE DATA TCTRL The STATUS pin will go high under any of the following conditions: STBY is high. This indicates that the chip is in “stand-by” mode. V5V is below the V5V UVLO threshold. PVDD is below the PVDD UVLO threshold. The die temperature is above about 140°C. This indicates that the part has gone in to gain foldback. A short circuit across the speaker has caused the output devices to shut off due to excessive temperature. Copyright © 2007 Rev. 1.3, 2007-04-05 WWW . Microsemi .C OM Name Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 3 LX1708 15+15W Stereo Filterless Class-D Amplifier ® TM P RODUCTION D ATA S HEET Parameter ` Symbol FOSC Temperature Stability Supply Voltage PVDD UVLO PVDD UVLO Hysteresis PVDD +5V Supply V5V UVLO V5V UVLO Hysteresis V5V 250 300 350 2 kHz % 5 Start-up Voltage, Rising 12 15 4.5 4.9 500 4.5 Start-up Voltage , Rising mV 5.5 4.25 V 4.50 250 V mV IQQ For PVDD, STBY high 10 50 µA Operating Current IQQ For PVDD, STBY low, Mute high 10 30 mA Stand-By Current IQQ5V5 For 5V5, STBY high 10 Operating Current IQQ5V5 For 5V5, STBY low, Mute high 7 1 PSRR For PVDD @ 1kHz VREF C bypass = 1µF 55 µA 15 mA dB 2.25 V GAIN Stage Gain G Mute Gain GMUTE OFFSET ` INPUT STAGE Output DC Offset VOFFSET f = 1kHz; VMUTE = 0V 26 VMUTE = 5V -40 Measured Differentially. Channel + to Channel - 40 mV dB Input Resistance RIN 22 kΩ Common Mode Voltage VCM 2.25 V 220 mΩ OUTPUT STAGE MOSFET On Resistance RDSON IDS = 200mA THERMAL Thermal Recovery Temperature TSD 150 TFB 140 TREC 110 ELECTRICALS Thermal Shut Down Junction Temperature Thermal Gain Fold-back Temperature ` Varies with ROSC resistor value, value shown is for default conditions. Stand-By Current ` ` Max POWER SUPPLY Reference Voltage ` Typ TA = -40°C to 85°C Power Supply Rejection Ratio ` Units Min OSCILLATOR Oscillator Frequency ` LX1708 Test Conditions WWW . Microsemi .C OM ELECTRICAL CHARACTERISTICS Unless otherwise specified, the following specifications apply over the operating ambient temperature -40°C < TA < 85°C except where otherwise noted and the following test conditions: PVDD = 12V, PVSS = AVSS = 0V, V5V = 5V, RROSC = 24.9kΩ °C MUTE / STBY MUTE Threshold MUTETH STBY Threshold STBYTH Mute Mode V5V 2 V V5V 2 STBY To Output Enable 5 ms Note 1: Not ATE Tested. Copyright © 2007 Rev. 1.3, 2007-04-05 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 4 LX1708 ® TM 15+15W Stereo Filterless Class-D Amplifier P RODUCTION D ATA S HEET Parameter ` Symbol Test Conditions Min LX1708 Typ Max Units AUDIO CHARACTERISTICS Output Power Stereo PO Total Harmonic Distortion Stereo THD+N Power Efficiency Channel Crosstalk VXTALK Audio Bandwidth Stage Gain Stereo Signal to Noise Ratio Output Noise Floor BW THD+N < 1% 12 THD+N <10% 15 POUT = 50% of Maximum Power, FIN = 1kHz with diodes POUT = 50% of Maximum Power, FIN = 1kHz No diodes W 0.4 % 0.4 POUT = 1W, FIN = 20Hz~20kHz 0.6 POUT = Max, THD+N < 1% 85 POUT = 1W, FIN = 1kHz -60 POUT = 1W, FIN = 20-20kHz WWW . Microsemi .C OM TYPICAL SYSTEM APPLICATION CHARACTERISTICS Unless otherwise specified, the following specifications apply over the operating ambient temperature -40°C < TA < 85°C except where otherwise noted and the following conditions: PVDD = 12V, PVSS = AVSS = 0V, V5V = 5V, ROSC = 25kΩ, RL = 4Ω. % 3 dB High VIN = 200mVRMS, F = 20Hz~20kHz 26 Low VIN = 2VRMS, FIN = 20Hz~20khz -40 SNR FIN = 1kHz @ 20Hz-20kHz non A-weighted 90 dB VN Input short, non A-weighted @ 20Hz-20kHz 200 µVRMS ELECTRICALS Copyright © 2007 Rev. 1.3, 2007-04-05 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 5 LX1708 15+15W Stereo Filterless Class-D Amplifier ® TM P RODUCTION D ATA S HEET SIMPLIFIED BLOCK DIAGRAM PVSS1P MUTE VREF BOOT1P + IN1P + PWM - IN1N - NFET H-BRIDGE OUT1P BOOT1N WWW . Microsemi .C OM PVDD1 OUT1N VREF PVSS1N MUTE MUTE PVDD ROSC OSC V5V VREF CONTROL BLOCK -UVLO -De-Pop Mute -Thermal STBY MUTE TCTRL STATUS TMON AVSS2 AVSS1 PVDD2 PVSS2P MUTE VREF BOOT2P + IN2P + PWM - IN2N - NFET H-BRIDGE OUT2P BOOT2N OUT2N PVSS2N MUTE Figure 1 – Simplified Block Diagram Copyright © 2007 Rev. 1.3, 2007-04-05 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 6 BLOCK DIAGRAM VREF LX1708 15+15W Stereo Filterless Class-D Amplifier ® TM P RODUCTION D ATA S HEET TEST SYSTEM SET-UP WWW . Microsemi .C OM 8 TO 4 OHM SPEAKER LOAD OR SPEAKER SIMULATOR +5V +/- 0.5V POWER SUPPLY TB2 LOW PASS FILTER AVSS + TB4 V5V OUT1P OUT1N J1 LOW PASS FILTER IN1P CHA AUDIO ANALYZER OUTPUT CHB TB1 PVDD IN1N LX1708 J2 PVSS LOW PASS FILTER CHA +5V TO +15V POWER SUPPLY AUDIO ANALYZER INPUT CHB TB3 IN2P OUT2N IN2N OUT2P LOW PASS FILTER LX1708 EVALUATION BOARD 8 TO 4 OHM SPEAKER LOAD OR SPEAKER SIMULATOR Figure 2 – System Test Set-up Diagram Note: Speaker Load is simulated with 8Ω resistor in series with 66µH inductor for 8Ω speaker and 4Ω resistor in series with 33µH inductor for 4Ω speaker APPLICATIONS Copyright © 2007 Rev. 1.3, 2007-04-05 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 7 LX1708 15+15W Stereo Filterless Class-D Amplifier ® TM P RODUCTION D ATA S HEET APPLICATION CIRCUITS +VIN VIN CR1 1N5817 C1 47µF 25V RTN R9 470 C23 4.7nF TB1 WWW . Microsemi .C OM TEST PURPOSE R8 470 TP4 RT-P C24 2.2nF CR2 1N5817 OUTR+ +5V OUTR- +5V TP2 1P C2 22µF 6.3V RTN TP3 1N TEST PURPOSE TB1 VIN VIN TP1 GND R6 470 C4 0.47µF INRJP1 HEADER 1 C5 0.47µF INL- C6 0.47µF INL+ MUTE JP2 HEADER 2 J2 +5V M L RCA Jack U1 Part LX1708 STATUS R1 24.9K C11 1µF C12 1µF TP6 STATUS +5V N +5V Header 3x2 C14 1µF TP7 GND C15 1µF C13 1µF C16 1µF VIN R10 124K C22 2.2nF OUT1N PVSS1N TCTRL TMON AVSS2 ROSC VREF AVSS1 V5V PVSS2N STBY IN1P IN1N N/C N/C IN2N IN2P C3 0.47µF INR+ OUT2N RCA Jack PVSS2P OUT2P BOOT2P PVDD2 PVDD2 BOOT2N SW1 SLEEP C21 4.7nF C9 1µF PVSS1P OUT1P BOOT1P PVDD1 PVDD1 BOOT1N C8 1µF +5V TP5 RT-N C10 1µF C7 1µF J1 R7 470 TP8 2P TEST PURPOSE TP10 LEFT-N VIN TP9 2N R2 470 C17 4.7nF R3 470 C18 2.2nF R11 75K CR8 1N5817 OUTLOUTL+ TEST PURPOSE R4 470 C19 4.7nF APPLICATIONS CR7 1N5817 TP1 LEFT-P R5 470 C20 2.2nF Note 1: CR1, CR2, CR7, CR8 can be used for lower distortion performance. Figure 3 – Typical Application Copyright © 2007 Rev. 1.3, 2007-04-05 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 8 LX1708 ® TM 15+15W Stereo Filterless Class-D Amplifier P RODUCTION D ATA S HEET FUNCTIONAL DESCRIPTION The LX1708 drives each output between PVDD and PVSS using an all-NFET, bootstrapped, H-bridge driver for each channel. High efficiency is obtained by forcing all transistors to operate either completely on or completely off as required for a true class-D amplifier. The entire signal path from input to output is differential to reject any sources of common-mode noise or distortion. Even the triangle wave operates differentially. Filterless class-D modulation operates such that with no input signal, the outputs switch at the programmed clock frequency and are in-phase with each other. Because the two signals are identical, the differential signal to the speaker is zero. As a direct result, there is no requirement for a low-pass LC filter to present high impedance at the modulation frequency. This allows a cheaper and simpler audio amplifier to be designed. As the input signal goes positive, the duty cycle to the positive output increases while the duty cycle of the negative output decreases. This produces a net positive current flow into the load. A negative signal reduces the positive output duty cycles and increases the negative output duty cycle. The differential signal actually appears at twice the modulation frequency and alternates between +PVDD, 0, and –PVDD which allows the parasitic inductance of the load to effectively filter the switching signal so that only the audio band portion remains. Because each speaker is driven by an in-phase signal, the common mode voltage to the speaker switches at the full PVDD amplitude at the clock frequency. This is a possible source of EMI radiation. Typically, a ferrite bead is placed with a small common-mode filter capacitor to reduce EMI generation by filtering the edges of the output signals. NOISE-FREE TURN-ON AND OFF Copyright © 2007 Rev. 1.3, 2007-04-05 AC-COUPLING AND BOOTSTRAP CAPACITORS Input AC-coupling capacitors should be used to block any input DC and low frequency components below the desired low frequency corner. Since the input resistance to the LX1708 is 25kΩ, a 20Hz low frequency corner can be achieved with a 0.33µF AC-coupling capacitor. 1µF bootstrap capacitors are required at each output to supply the gate drive voltage for the upper level NFET in each half-bridge. THERMAL OVERLOAD PROTECTION The LX1708 protects itself by monitoring its operating temperature in two different ways. A general thermal protection scheme monitors the overall die temperature. Above 140°C, the amplifier gain is reduced by 6dB so that the audio signal is still amplified, but the on-chip power dissipation is halved. When the die temperature goes below 110°C, the amplifier gain is restored. Above 150°C, the LX1708 forces all outputs to PVSS so that no power is dissipated until the chip cools down to 110°C. A dynamic thermal protection scheme operates by placing temperature sensors near each of the output devices. When a differential temperature rise of about 60°C occurs above the core die temperature, the outputs are disabled to protect the part. This provides short circuit protection for differential shorts across the output. Shorts to PVDD and ground (PVSS) are not protected. Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 9 APPLICATIONS Noise-free turn-on and off is accomplished by carefully sequencing the signal path when the amplifier is enabled or disabled. Prior to turn-on, the outputs are initially both at PVSS so there is no differential signal. The internal error amplifier is held in a reset condition so that the internal loop compensation components are “ready to go”. When the outputs begin to toggle, the audio signal path is muted for about 1.6ms. Following that time, the internal mute signal is de-asserted and the audio input signal is allowed to drive the pulse-width–modulator which then adjusts the output duty cycle as necessary to drive the speaker. At turn-off, the internal mute signal is asserted to silence the input audio signal. The outputs continue switching in this muted condition for about 0.6ms prior to being pulled low. Once the outputs are forced low, the error amplifier is reset so that the part is ready to begin a new power-up sequence. This scheme basically limits the pop noise at turn-on or off to be no larger than the differential offset voltage of the error amplifier. WWW . Microsemi .C OM FILTERLESS CLASS-D MODULATION LX1708 ® TM 15+15W Stereo Filterless Class-D Amplifier P RODUCTION D ATA S HEET APPLICATION NOTE/PCB DESIGN GUIDELINE The value of ROSC selects the switching frequency; smaller values increase the switching frequency. See Figure 4, Typical Switching Frequency vs. ROSC. The recommended range of ROSC is between 17.5KΩ and 42.5KΩ Sw itching Frequency vs ROSC SW FREQ (kHz) 450 400 350 300 250 200 150 17.5 22.5 27.5 32.5 37.5 42.5 ROSC (kOhm s) Figure 4 – Typical Switching Frequency vs. ROSC BOOTSTRAP CAPACITORS C8, C9, C14, and C15 are bootstrap capacitors for internal NMOSFETs gate drive voltage, they work together with internal diodes to provide sufficient gate drive voltage for upper MOSFETS. Those capacitors should be placed as close to the IC as possible. BYPASSING CAPACITORS C7, C10, C11, C12, C13, and C16 are bypassing capacitors for input supplies and internal reference voltage (VREF), nominal value is 1µF. These capacitors should be placed as close to the IC as possible, to guarantee low ripple and noise. PCB DESIGN GUIDELINES Component placement for the LX1708 should be done such that low-level inputs to the LX1708 are routed away from the high frequency switching outputs. Special care should be given to the bypass and bootstrap capacitors. Capacitors (C7, C10, C13, C16, C8, C9, C14, and C15 in the application schematic), should be placed as close to the IC as possible. If workable, they should be mounted on the same layer as the IC, with a direct connection to the IC on that layer. It is best not to use vias to establish the critical connection of these components to the LX1708. Bypass capacitors for V5V input, as well as VREF (C11 and C12 in the application schematic), should be mounted close to the IC as well. WWW . Microsemi .C OM OSCILLATOR One of the key efforts in implementing the MLP package on a pc board is the design of the land pattern. The MLP has a rectangular exposed thermal pad on the bottom surface of the package body. Electrical and mechanical connection between the component and the pc board is made by screen printing solder paste on the pc board and then reflowing the paste after placement. To guarantee reliable solder joints it is essential to properly design the land pattern to the MLP terminal pattern, exposed thermal pad, and thermal pad vias. There are two basic designs for PCB land pads for the MLP: Copper Defined style (also known as Non Solder Mask Defined (NSMD)) and the Solder Mask Defined style (SMD). The industry has had some debate on the merits of both styles and although Microsemi recommends the Copper Defined style land pad (NSMD). Both styles are acceptable for use with the MLP package. NSMD pads are recommended over SMD pads due to the tighter tolerance on copper etching than solder masking. NSMD by definition also provides a larger copper pad area and allows the solder to anchor to the edges of the copper pads thus providing improved solder joint reliability. APPLICATIONS Copyright © 2007 Rev. 1.3, 2007-04-05 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 10 LX1708 ® TM 15+15W Stereo Filterless Class-D Amplifier P RODUCTION D ATA S HEET APPLICATION NOTE/PCB DESIGN GUIDELINE (CONTINUED) The construction of the Exposed Pad MLP enables enhanced thermal and electrical characteristics. In order to take full advantage of this feature the exposed pad must be physically connected to the PCB substrate with solder. The exposed pad is internally connected to the die substrate, so it is very important that the PCB substrate potential be connected to the same potential as AVSS. The PCB thermal pad dimensions should be greater than the dimensions of the MLPQ thermal pad whenever possible; however adequate clearance must be met to prevent solder bridging to the outer pads. A minimum clearance of 0.2mm is recommended. If this clearance cannot be met, then the PCB thermal pad should be reduced in area. 7.55 [0.297] 5.10 [0.201] MAX. CL Ø0.30 [Ø0.012] OPTIONAL 16 PLS. 1.20 [0.047] TYP. CL 5.10 [0.201] MAX. 7.55 [0.297] 1.20 [0.047] TYP. 0.98 [0.038] MAX. TYP. 32 PLS. THERMAL PAD VIA DESIGN 0.65 [0.026] TYP. 28 PLS. There are two types of on-board thermal pad designs: one using thermal vias to sink the heat to an inner layer utilizing a copper plane. Based on the JEDEC Specification (JESD 51-5) the thermal vias should be designed similar to Figure 5, with the following specifications: 0.43 [0.017] MAX. TYP. 32 PLS. ALL DIMENSIONS IN MM [ IN ]. Figure 5 – Recommended Land Pad with Vias for 7x7mm LQ package Via Barrel diameter: 0.3mm Min. Via Barrel plating: 0.025mm Center to center spacing: 1.2mm For the LX1708 7x7mm MLPQ package, there will be enough space for 16 vias. This method is recommended for use on a multilayer board, and will give the best thermal performance. Thermal vias may be used on a two layer board as well, with reduced performance. Another method is the no via thermal pad, which uses only the copper pad as a heat sink, and relies on the PCB substrate material for thermal conduction. This type of thermal pad is good for a two layer board; however thermal performance will not be as good as the thermal via method on a multilayer board. Copyright © 2007 Rev. 1.3, 2007-04-05 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 11 WWW . Microsemi .C OM EXPOSED PAD PCB DESIGN LX1708 15+15W Stereo Filterless Class-D Amplifier ® TM P RODUCTION D ATA S HEET THD+N VS. OUTPUT POWER THD+N VS. OUTPUT POWER WWW . Microsemi .C OM 12V, 8 Ohm Load with External Diodes 100 100 50 50 20 20 10 10 5 5 2 2 1 1 0.5 0.5 % % 0.2 0.2 0.1 0.1 0.05 0.05 0.02 0.02 0.01 0.01 0.005 0.005 0.002 0.001 0.002 60m 100m 200m 500m 1 2 5 10 0.001 20 60m 100m 200m 500m W 1 2 5 10 20 W THD VS. POWER SUPPLY THD+N VS. OUTPUT POWER 12V, 4 Ohm Load, No External Diodes 12V, 4 Ohm Load, With External Diodes 100 100 50 50 20 20 10 10 5 5 2 2 1 1 0.5 0.5 % % 0.2 0.2 0.1 0.1 0.05 0.05 0.02 0.02 0.01 0.01 0.005 0.005 0.002 0.002 0.001 60m 100m 200m 500m 1 2 5 10 0.001 20 60m 100m 200m 500m W 1 2 5 10 20 10 20 W THD+N VS. FREQUENCY THD+N VS. FREQUENCY 12V, 8 Ohm Load, No External Diodes 12V, 8 Ohm Load, with External Diodes 100 50 50 20 20 10 10 5 5 2 2 CHARTS 100 1 1 0.5 0.5 % % 0.2 0.2 0.1 0.1 0.05 0.05 0.02 0.02 0.01 0.01 0.005 0.005 0.002 0.002 0.001 0.001 60m 100m 200m 500m 1 2 5 10 20 Copyright © 2007 Rev. 1.3, 2007-04-05 60m 100m 200m 500m 1 2 5 W W Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 12 LX1708 15+15W Stereo Filterless Class-D Amplifier ® TM P RODUCTION D ATA S HEET THD+N VS. FREQUENCY THD+N VS. FREQUENCY 100 12V, 4 Ohm Load, With External Diodes 100 50 50 20 20 10 10 5 5 2 2 1 WWW . Microsemi .C OM 12V, 4 Ohm Load, No External Diodes 1 0.5 0.5 % % 0.2 0.2 0.1 0.1 0.05 0.05 0.02 0.02 0.01 0.01 0.005 0.005 0.002 0.002 0.001 20 50 100 200 500 1k 2k 5k 10k 0.001 20 20k 50 100 200 500 Hz THD VS. POWER SUPPLY 2k 5k 10k 20k THD VS. POWER SUPPLY 8 Ohm Load, 6V, 9V, 12V, 15V 100 1k Hz 4 Ohm Load, 6V, 9V, 12V, 15V 100 50 50 20 6V 10 20 15V 6V 10 5 5 2 2 1 1 0.5 0.5 % 15V % 0.2 0.2 0.1 0.1 0.05 0.05 0.02 0.02 0.01 0.01 0.005 0.005 0.002 0.002 0.001 60m 100m 200m 500m 1 2 5 10 0.001 20 60m W 200m 500m 1 2 5 10 20 50 W OUTPUT POWER BANDWIDTH @ 1% THD OUTPUT POWER BANDWIDTH @ 1% THD 12V, 8 Ohm Load 20 100m 12V, 4 Ohm Load 30 20 10 10 7 6 8 5 6 4 5 W 3 4 CHARTS W 3 2 2 1 1 800m 700m 600m 20 600m 50 100 200 500 1k 2k 5k 10k 20k Hz Copyright © 2007 Rev. 1.3, 2007-04-05 20 50 100 200 500 1k 2k 5k 10k 20k Hz Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 13 LX1708 15+15W Stereo Filterless Class-D Amplifier ® TM P RODUCTION D ATA S HEET PSRR @ 8 OHM CHANNEL CROSSTALK @ 8 OHM Channel Crosstalk @ 8 ohm +0 +0 -10 -10 -20 -20 -30 -30 -40 -40 dB dBr WWW . Microsemi .C OM PSRR @ 8 ohm -50 -50 -60 -60 -70 -70 -80 -80 -90 -90 -100 20 -100 20 50 100 200 500 1k 2k 5k 10k 20k 50 100 200 500 SIGNAL TO NOISE RATIO @ 8 OHM 2k 5k 10k 20k NOISE FLOOR @ 8 OHM SNR @ 8 ohm +0 1k Hz Hz Noise Floor @ 8 ohm +0 -10 -10 -20 -20 -30 -30 -40 -40 dBV dBr -50 -50 -60 -70 -60 -80 -70 -90 -80 -100 -90 -110 -100 20 50 100 200 500 1k 2k 5k 10k 20k -120 20 50 100 200 Hz 500 1k 2k 5k 10k 20k Hz PVDD CURRENT VS. OUTPUT POWER EFFICIENCY 12V, 4 Ohm Load + 33µH 12V, 4 Ohm Load + 33µH 100% 3.0 95% 2.5 90% 85% 2.0 80% 75% 1.5 CHARTS 70% 1.0 65% 60% 0.5 55% 0.0 50% 0 5 10 15 20 25 30 Ou t p u t P o we r - 2 C h a n ne l s T o t a l ( Wa t t s R M S ) Copyright © 2007 Rev. 1.3, 2007-04-05 0 5 10 15 20 25 30 Ou t p ut P owe r - 2 C ha nn e l s T ot a l ( Wa t t s R M S ) Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 14 LX1708 ® TM 15+15W Stereo Filterless Class-D Amplifier P RODUCTION D ATA S HEET IQQ VS. FREQUENCY GAIN @ 8 OHM WWW . Microsemi .C OM GAIN @ 8 ohm 40 +30 35 +28 +26 30 +24 +22 +20 +18 20 dBr IQQ (mA) 25 +16 +14 15 +12 +10 10 +8 +6 5 +4 0 150k +2 250k 350k 450k 550k 650k 750k 850k 950k 1,050k 1,150k SW Freq. (Hz) +0 20 50 100 200 500 1k 2k 5k 10k 20k 50k 80k Hz CHARTS Copyright © 2007 Rev. 1.3, 2007-04-05 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 15 LX1708 15+15W Stereo Filterless Class-D Amplifier ® TM P RODUCTION D ATA S HEET PACKAGE DIMENSIONS WWW . Microsemi .C OM LQ 32-Pin MLPQ Plastic (7x7mm EP) D E2 b L D2 E e MILLIMETERS MIN MAX 0.80 1.00 0 0.05 0.25 REF 0.23 0.38 7.00 BSC 5.00 5.25 7.00 BSC 5.00 5.25 0.65 BSC 0.45 0.65 INCHES MIN MAX 0.031 0.039 0 0.002 0.010 0.009 0.015 0.276 BSC 0.197 0.207 0.276 BSC 0.197 0.207 0.026 0.018 0.026 Note: A A1 Dim A A1 A3 b D D2 E E2 e L 1. Dimensions do not include mold flash or protrusions; these shall not exceed 0.155mm (.006”) on any side. Lead dimension shall not include solder coverage. A3 MECHANICALS Copyright © 2007 Rev. 1.3, 2007-04-05 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 16 LX1708 TM ® 15+15W Stereo Filterless Class-D Amplifier P RODUCTION D ATA S HEET NOTES WWW . Microsemi .C OM NOTES PRODUCTION DATA – Information contained in this document is proprietary to Microsemi and is current as of publication date. This document may not be modified in any way without the express written consent of Microsemi. Product processing does not necessarily include testing of all parameters. Microsemi reserves the right to change the configuration and performance of the product and to discontinue product at any time. Copyright © 2007 Rev. 1.3, 2007-04-05 Microsemi Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570 Page 17