A Product Line of Diodes Incorporated PAM8902A 30 VPP MONO CLASS-D AUDIO AMPLIFIER FOR PIEZO/CERAMIC SPEAKERS WITH ANTI-SATURATION Description Pin Assignments The PAM8902A is a mono, Class-D audio amplifier with integrated boost convertor designed for piezo and ceramic speakers. The PAM8902A is capable for driving a ceramic/piezo speaker with 30VPP(0.6Vrms) from a 3.6V power supply. The PAM8902A's boost converter operates at a fixed frequency of 1.5MHz and provides a 17.5V supply with a minimum number of external components. The three gain mode of 18dB, 22dB and 26dB is easy for using. PAM unique ant i -saturat ion technology which detects output signal clip due to the over level input signal suppress the output signal clip automatically. PAM8902A features an integrated audio low pass filter that rejects high frequency noise, thus improving audio fidelity. PAM8902A also provides thermal, over current, under and over voltage protection. The PAM8902A is available in a 16-ball 1.95mm x 1.95mm CSP package and 16-pin QFN4x4 package. Features • • Supply Voltage Range from 2.7V to 5.5V package. 30VPP Output Load Voltage from a 2.7V Supply • Integrated Boost Converter Generates 17.5V Supply • Programmable Soft-Start • Unique Anti-Saturation Function • Small Boost Converter Inductor • Selectable Gain of 18dB, 22dB, and 26dB (Refer to “Application Notes”) • Selectable Boost output voltage of 8V, 12V, and 17.5V • Low Shutdown Current: <1µA • Build in Thermal, OCP, UVLO, OVP • Available in Space Saving Packages: 16-ball 1.95mm x 1.95mm CSP package 16-pin QFN4x4 package Applications • Wireless or Cellular Handsets • Portable DVD Player • Personal Digital Assistants (PDAs ) • Electronic Dictionaries • Digital Still Cameras PAM8902A Document number: DSxxxxx Rev. 1 - 3 1 of 12 www.diodes.com February 2013 © Diodes Incorporated A Product Line of Diodes Incorporated PAM8902A Typical Applications Circuit Pin Descriptions Bump (CSP) A1 A2 A3 A4 B1 B2 B3 B4 C1 C2 C3 C4 D1 D2 D3 D4 Pin Number (QFN) 13 1 2 4 15 3 5 6 14 11 7 8 13 12 10 9 PAM8902A Document number: DSxxxxx Rev. 1 - 3 Pin Name PVCC VOUT SW PGND1 OUTP VSET COMP AVDD OUTN GSET VCM AGND PGND2 ENA INN INP Function Audio Amplifier Power Supply Boost Convertor Output Boost Convertor Switching Node Boost Convertor Power Ground Positive Differential Audio Output Boost Convertor Output Voltage Setting(8V,12V,17.5V) Boost Convertor Compensation Power Supply Negative Differential Audio Output AmplifierGain Setting. (Refer to "Application Notes") Common Mode Bypass Cap Analog Ground Class D PowerGround Whole Chip Enable Negative Differential Audio Input Positive Differential Audio Input 2 of 12 www.diodes.com February 2013 © Diodes Incorporated A Product Line of Diodes Incorporated PAM8902A Functional Block Diagram Absolute Maximum Ratings (@TA = +25°C, unless otherwise specified.) These are stress ratings only and functional operation is not implied. Exposure to absolute maximum ratings for prolonged time periods may affect device reliability. All voltages are with respect to ground. Parameter Supply Voltage Input Voltage Maximum Junction Temperature Storage Temperature Soldering Temperature Rating 6.0 -0.3 to VDD +0.3 +150 -65 to +150 250, 10 sec Unit V °C Recommended Operating Conditions (@TA = +25°C, unless otherwise specified.) Parameter Supply Voltage Range Ambient Temperature Range Junction Temperature Range PAM8902A Document number: DSxxxxx Rev. 1 - 3 Rating 2.7 to 5.5 -40 to +85 -40 to +125 Unit V °C °C 3 of 12 www.diodes.com February 2013 © Diodes Incorporated A Product Line of Diodes Incorporated PAM8902A Thermal Information Parameter Thermal Resistance (Junction to Ambient) Thermal Resistance (Junction to Case) Package CSP QFN4x4-16 CSP QFN4x4-16 Symbol θJA θJC Max 90 – 220 37 75 2 Unit °C/W Electrical Characteristics (@TA = +25°C, VDD = 3.6V, CL = 1µF, VSET floating, RLOAD = 10Ω, LLOAD = 22µh with external schottky diodes, unless otherwise specified.) Parameter Input Voltage Symbol Test Conditions Min Typ 2.7 VDD Max Units 5.5 V EN > 1.2V, VSET = High 30 48 10 18 mA Quiescent Current IQ EN > 1.2V, VSET = Floating 5 12 Shutdown Current ISD EN = 0V 0.1 1 Wake-Up Time TWU EN from Low to High 40 Chip Enable VEH Chip Disable VEL GSET/ VSET High VH VDD -0.5 VDD GSET/ VSET Floating VF 1 VDD -1 GSET/ VSET Low VL 0 0.5 EN > 1.2V, VSET = GND 1.2 V 0.4 Under Voltage Lockout Threshold UVLO VDD from High to Low 2.2 Under Voltage Lockout Hysteresis UVLO(H) VDD from Low to High 0.2 Thermal Shutdown Threshold Thermal Shutdown Lockout Hysyeresis Boost Converter µA mS OTP OTP(H) V V 150 30 °C °C V O1 VSET = Low, No Load 7.2 8.0 8.8 V V O2 VSET = Floating, No Load 10.8 12.0 13.2 V V O3 VSET = High, No Load 16.0 17.5 19.0 Current Limit CL Average Input Current 0.8 A Lowside MOSFET RDS(ON) RLS IO = 50mA 0.5 Ω Boost Switching Frequency fOSCB Over Voltage Protection Threshold VOVP Output Voltage 1.1 1.5 1.9 18 V MHz V Class D Class D Amplifier Switching Frequency fOSCD Input AC-GND Common Mode Reject Ratio CMRR VIN = ±100mV, VDD = 3.6V 60 5 225 375 475 KHz 50 mV dB Output Offset Voltage VOS Output Offset Voltage RDS(ON) RP High Side Low Side AV1 GSET = High, VO = 1VRMS AV2 GSET = Floating, VO = 1VRMS 21 22 23 AV3 GSET = Low, VO = 1VRMS 17 18 19 Closed-Loop Voltage Gain 1.5 0.6 25 26 Ω Ω 27 dB Power Supply Reject Ratio PSRR 200m VPP Supply Ripple @ 217Hz 70 Total Harmonic Distortion Plus Noise THD+N VO = 5VRMS Input AC Ground, A-Weighting 0.3 % 90 dB Signal to Noise Ratio PAM8902A Document number: DSxxxxx Rev. 1 - 3 SNR 4 of 12 www.diodes.com dB February 2013 © Diodes Incorporated A Product Line of Diodes Incorporated PAM8902A Typical Performance Characteristics (@TA = +25°C, VDD = 3.6V, CL = 1µF, L = 4.7µH, VSET floating, RLOAD = 10Ω, LLOAD = 22µH, with external schottky diode, unless otherwise specified.) PAM8902A Document number: DSxxxxx Rev. 1 - 3 5 of 12 www.diodes.com February 2013 © Diodes Incorporated A Product Line of Diodes Incorporated PAM8902A Typical Performance Characteristics (cont.) (@TA = +25°C, VDD = 3.6V, CL = 1µF, L = 4.7µH, VSET floating, RLOAD =10Ω, LLOAD = 22µH, with external schottky diode, unless otherwise specified.) PAM8902A Document number: DSxxxxx Rev. 1 - 3 6 of 12 www.diodes.com February 2013 © Diodes Incorporated A Product Line of Diodes Incorporated PAM8902A Application Information Select Boost Converter Output Voltage The VSET pin sets the boost converter output voltage to 8V, 12V or 17.5V. VSET pin configuration table as below: VSET Pin Configuration Min Max PVCC Voltage Audio Amplifier Maximum Output Voltage 11 VRMS (VPP = 31.1V) High AVDD – 0.5 AVDD 17.5V Floating 1V AVDD – 1V 12V 8 VRMS (VPP = 22.6V) Low GND 0.5V 8V 5 VRMS (VPP = 14.1V) Gain Setting and Input Resistance (RI) Gain setting function is only available in disable condition (ENA = low) and need to follow the sequence as pull ENA to low (disable the IC) first, and change the GSET voltage between high, floating, low, then pull ENA to high (enable the IC). The input resistors (RI = RIN + REX) set the gain of the amplifier according to Equation 1 when anti-saturation is inactive. G = 20 Log [12.8*RF/ (RIN + REX)] (dB) GSET RIN RFB High 77.4kΩ 122.6kΩ Floating 100kΩ 100kΩ Low 122.6kΩ 77.4kΩ Where RIN is a 77.4KΩ internal resistor, REX is the external input resistor, RF is a 122.6KΩ internal resistor. Resistor matching is very important in fully differential amplifiers. The balance of the output on the reference voltage depends on matched ratios of the resistors. CMRR, PSRR, and cancellation of the second harmonic distortion diminish if resistor mismatch occurs. Therefore, it is recommended to use 1% tolerance resistors or better to keep the performance optimized. Matching is more important than overall tolerance. Resistor arrays with 1% matching can be used with a tolerance greater than 1%. Place the input resistors very close to the PAM8902A to limit noise injection on the high-impedance nodes. For optimal performance the gain should be set to lower. Lower gain allows the PAM8902A to operate at its best, and keeps a high voltage at the input making the inputs less susceptible to noise. In addition to these features, higher value of RI minimizes pop noise. Anti-Saturation/Clipping Function The anti-saturation circuitry detects the duty cycle of the PWM output. When the output starts to exhibit clipping, the gain is automatically decreased with an attack time of 100µs per step a release time of 186ms per step. The following table describes the operation: Variable Gain Description Value The original gain of the device when the Anti-saturation is inactive. Attenuation Range The gain control range when anti-saturation is active. Step Size Attack Time Release Time Gain adjust step size. The minimum time between two gain decrements. The minimum time between two gain increments. PAM8902A Document number: DSxxxxx Rev. 1 - 3 7 of 12 www.diodes.com 26dB (GSET = High) 22dB (GSET = Floating) 18dB (GSET = Low) -26dB (GSET = High) -22dB (GSET = Floating) -18dB (GSET = Low) 0.25dB/Step 100µs 186ms February 2013 © Diodes Incorporated A Product Line of Diodes Incorporated PAM8902A Application Information (cont.) Input Capacitors (CI) In the typical application, an input capacitor, CI, is required to allow the amplifier to bias the input signal to the proper DC level for optimum operation. In this case, CI and the minimum input impedance RI form is a high-pass filter with the corner frequency determined in the follow equation: fC = 1 2Π RI CI It is important to consider the value of CI as it directly affects the low frequency performance of the circuit. For example, when RI is 150k and the specification calls for a flat bass response are down to 150Hz. Equation is reconfigured as followed: CI = 1 2Π RIFC When input resistance variation is considered, the CI is 7nF, so one would likely choose a value of 10nF. A further consideration for this capacitor is the leakage path from the input source through the input network (CI, RI + RF) to the load. This leakage current creates a DC offset voltage at the input to the amplifier that reduces useful headroom, especially in high gain applications. For this reason, a low-leakage tantalum or ceramic capacitor is the best choice. When polarized capacitors are used, the positive side of the capacitor should face the amplifier input in most applications as the DC level is held at VDD /2, which is likely higher than the source DC level. Please note that it is important to confirm the capacitor polarity in the application. Decoupling Capacitor The PAM8902 is a high-performance CMOS audio amplifier that requires adequate power supply decoupling to ensure the output total harmonic distortion (THD) as low as possible. The optimum decoupling is achieved by using two different types of capacitors that target on different types of noise on the power supply leads. For higher frequency transients, spikes, or digital hash on the line, a good low equivalent series-resistance (ESR) ceramic capacitor, typically 1µF is placed as close as possible to the device AVDD pin for the best operation. For filtering lower frequency noise signals, a large ceramic capacitor of 10µF or greater placed near the AVDD supply trace is recommended. External Schottky Diode Use external schottky diode can get the best driving capability and efficiency. Since internal power diode has limited driving capability, only in following conditions customer can remove the external schottky diode to reduce the cost. 1. VSET = Low or Floating and CL less than 1µF. 2. The signal frequency less than 4KHz. 3. Haptic application (50–500Hz). Shutdown Operation In order to reduce power consumption while not in use, the PAM8902A contains shutdown circuitry amplifier off when a logic low is placed on the ENA pin. By switching the ENA pin connected to GND, the PAM8902A supply current draw will be minimized in idle mode. Under-Voltage Lock-Out (UVLO) The PAM8902A incorporates circuitry designed to detect supply voltage. When the supply voltage drops to 2.2V or below, the PAM8902A goes into a state of shutdown, and the device comes out of its shutdown state and restore to normal function only when reset the power supply or ENA pin. Over-Temperature Protection (OTP) Thermal protection on the PAM8902A prevents the device from damage when the internal die temperature exceeds +150°C. There is a 15°C tolerance on this trip point from device to device. Once the die temperature exceeds the set point, the device will enter the shutdown state and the outputs are disabled, in this condition both OUTP and OUTN will become high impedance. This is not a latched fault. The thermal fault is cleared once the temperature of the die decreased by 30°C. This large hysteresis will prevent motor boating sound well and the device begins normal operation at this point with no external system interaction. PAM8902A Document number: DSxxxxx Rev. 1 - 3 8 of 12 www.diodes.com February 2013 © Diodes Incorporated A Product Line of Diodes Incorporated PAM8902A Ordering Information Part Number PAM8902AZER PAM8902AKER Part Marking BN YW P8902A XXXYW Package Type Standard Package CSP-16L 3000Units/Tape&Reel QFN4x4-16L 3000Units/Tape&Reel Marking Information PAM8902A Document number: DSxxxxx Rev. 1 - 3 9 of 12 www.diodes.com February 2013 © Diodes Incorporated A Product Line of Diodes Incorporated PAM8902A Package Outline Dimensions (All dimensions in mm.) CSP-16 PAM8902A Document number: DSxxxxx Rev. 1 - 3 10 of 12 www.diodes.com February 2013 © Diodes Incorporated A Product Line of Diodes Incorporated PAM8902A Package Outline Dimensions (cont.) (All dimensions in mm.) QFN4x4-16 PAM8902A Document number: DSxxxxx Rev. 1 - 3 11 of 12 www.diodes.com February 2013 © Diodes Incorporated A Product Line of Diodes Incorporated PAM8902A IMPORTANT NOTICE DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS DOCUMENT, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION). Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes without further notice to this document and any product described herein. Diodes Incorporated does not assume any liability arising out of the application or use of this document or any product described herein; neither does Diodes Incorporated convey any license under its patent or trademark rights, nor the rights of others. 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Copyright © 2013, Diodes Incorporated www.diodes.com PAM8902A Document number: DSxxxxx Rev. 1 - 3 12 of 12 www.diodes.com February 2013 © Diodes Incorporated