High Efficiency, Ground-Referenced Class-G Headphone Amplifier SSM2932 Data Sheet FEATURES GENERAL DESCRIPTION Ground-referenced Class-G output stage Very high efficiency for portable applications 1.7 mA typical quiescent current 50 mW per channel into 16 Ω load (with 3.3 V supply) 98 dB signal-to-noise ratio (SNR), A-weighted 90 dB power supply rejection ratio at 217 Hz 2.5 V to 3.6 V supply range Selectable gain: 0 dB or 6 dB High-Z output mode for sharing of output jack 1 μA shutdown current Short-circuit protection Pop-and-click reduction circuitry 8 kV ESD protection on output terminals 16-ball, 0.4 mm pitch WLCSP (1.64 mm × 1.64 mm) −40°C to +85°C operating temperature range The SSM2932 is a stereo headphone amplifier capable of delivering 50 mW of continuous output power per channel into 16 Ω single-ended loads at the 1% THD + N threshold. The stereo headphone drivers are high efficiency, true groundreferenced Class-G technology. The SSM2932 incorporates a gain control pin that selects a gain of 0 dB or 6 dB. The ground-referenced output scheme eliminates the need for large dc blocking capacitors, reducing system cost and board area. The Class-G amplifier is fine-tuned to maximize battery life, a critical task in portable applications. The device maximizes battery life by modulating the amplifier power supply rail to match the output demand without consuming excessive supply current, thus reducing power dissipation during typical audio playback. The SSM2932 is specified over the industrial temperature range of −40°C to +85°C. It has output short-circuit protection as well as ESD protection to 8 kV (human body model). The SSM2932 is available in a 16-ball, 1.64 mm × 1.64 mm wafer level chip scale package (WLCSP). APPLICATIONS Cell phones Smartphones/multimedia phones Digital cameras Portable media players Phone accessories PDAs POR GAIN CPVSS CPVDD CF2 CF1 GAIN HI-Z SD FUNCTIONAL BLOCK DIAGRAM POWER MANAGEMENT INL+ INL– PVDD PGND OUTR PGA SGND INR+ INR– OUTL PGA POP/ CLICK CURRENT LIMIT 10360-001 SSM2932 Figure 1. Rev. 0 Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 ©2012 Analog Devices, Inc. All rights reserved. SSM2932 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Typical Performance Characteristics ..............................................7 Applications....................................................................................... 1 Theory of Operation ...................................................................... 12 General Description ......................................................................... 1 Amplifier Gain............................................................................ 12 Functional Block Diagram .............................................................. 1 Amplifier Shutdown................................................................... 12 Revision History ............................................................................... 2 High Output Impedance ........................................................... 12 Specifications..................................................................................... 3 Ground Sense.............................................................................. 12 Digital Input Specifications......................................................... 4 Layout .......................................................................................... 12 Absolute Maximum Ratings............................................................ 5 Typical Application Circuit ........................................................... 14 Thermal Resistance ...................................................................... 5 Outline Dimensions ....................................................................... 15 ESD Caution.................................................................................. 5 Ordering Guide .......................................................................... 15 Pin Configuration and Function Descriptions............................. 6 REVISION HISTORY 2/12—Revision 0: Initial Version Rev. 0 | Page 2 of 16 Data Sheet SSM2932 SPECIFICATIONS PVDD = 3.0 V, CCF = 1 μF, CCPVDD = CCPVSS = 2.2 μF, RL = 32 Ω, TA = 25°C, unless otherwise noted. Table 1. Parameter DEVICE CHARACTERISTICS Voltage Gain Output Power Total Harmonic Distortion Plus Noise Gain Matching Frequency Range Differential Input Impedance CHARGE PUMP Oscillator Frequency Headphone Amplifier Supply Positive Rail Negative Rail Output Voltage Threshold Symbol Test Conditions/Comments AV Input voltage = 100 mV rms GAIN pin high GAIN pin low f = 1 kHz, THD = 1% RL = 16 Ω, one channel RL = 32 Ω, one channel RL = 16 Ω, stereo RL = 32 Ω, stereo PO = 10 mW per channel PO THD + N ΔAV Ripple within ±0.5 dB ZIN Max Unit 6 0 dB dB 85 50 40 45 0.01 mW mW mW mW % % Hz kΩ 18 1 20,000 34.5 Idle mode, VOUT = 0 V Active mode 54 550 kHz kHz VCPVDD Efficiency mode: VOUT < 0.2 V rms High power mode: VOUT > 0.2 V rms Efficiency mode: VOUT < 0.2 V rms High power mode: VOUT > 0.2 V rms Transition from efficiency mode to high power mode Transition from high power mode to efficiency mode Charge pump transition from high power mode to efficiency mode Charge pump transition from efficiency mode to high power mode PVDD/2 2.2 −PVDD/2 −2.2 285 V V V V mV 375 mV 0.8 ms 10 μs BW = 20 kHz, A-weighted, gain = 0 dB A-weighted 12 98 −60 86 μV rms dB dBV dB VCPVSS VTH1 tRELEASE tATTACK NOISE PERFORMANCE Output Voltage Noise Signal-to-Noise Ratio Pop-and-Click Noise Channel Separation OUTPUT CHARACTERISTICS Output Offset Voltage Capacitive Output Drive Slew Rate STARTUP AND SHUTDOWN Start-Up Time Shutdown Time POWER SUPPLY Supply Voltage Range Quiescent Current Shutdown Current Power Supply Rejection Ratio 20 12 Typ fOSC0 fOSC1 VTH2 Charge Pump Transition Time Min en SNR VCP XTALK Single-ended, 1 V rms, PO = 31 mW |VOS| CLOAD SR 150 1.25 0.25 mV pF V/μs 20 36 ms μs Measured from SD rising edge tSU tSD PVDD IDD ISD PSRR 0°C < TA < 70°C Guaranteed from PSRR test RL = 32 Ω + 200 pF; gain = 0 dB, PVDD = 3 V SD = GND VRIPPLE = 100 mVPEAK, gain = 0 dB f = 217 Hz f = 1 kHz f = 10 kHz Rev. 0 | Page 3 of 16 2.5 1.7 1 3.6 V mA μA 90 84 62 dB dB dB SSM2932 Data Sheet DIGITAL INPUT SPECIFICATIONS Table 2. Parameter Input Voltage High Input Voltage Low Input Leakage Current Input Capacitance Symbol VIH VIL IIN CIN Test Conditions/Comments VIN = 0 V or VDD Rev. 0 | Page 4 of 16 Min Typ 1.2 0.5 Max ±1 5 Unit V V μA pF Data Sheet SSM2932 ABSOLUTE MAXIMUM RATINGS TA = 25°C, unless otherwise noted. THERMAL RESISTANCE Table 3. θJA is specified for the worst-case conditions, that is, a device soldered in a circuit board for surface-mount packages. Parameter Analog Supply Voltage (PVDD) Input Voltage Output ESD, Human Body Model Storage Temperature Range Operating Temperature Range Junction Temperature Range Lead Temperature (Soldering, 60 sec) Rating 3.75 V 1.8 VPEAK 8 kV −65°C to +150°C −40°C to +85°C −65°C to +165°C 300°C Table 4. Thermal Resistance Package Type 16-Ball, 1.64 mm × 1.64 mm WLCSP ESD CAUTION Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Rev. 0 | Page 5 of 16 θJA 66 Unit °C/W SSM2932 Data Sheet PIN CONFIGURATION AND FUNCTION DESCRIPTIONS BALL A1 INDICATOR 2 1 3 4 SD PVDD OUTL INL– PGND CF1 CPVDD INL+ A B CF2 CPVSS SGND INR+ C HI-Z GAIN OUTR INR– TOP VIEW (BALL SIDE DOWN) Not to Scale Figure 2. Pin Configuration Table 5. Pin Function Descriptions Pin No. A1 B1 C1 D1 A2 B2 C2 D2 A3 B3 C3 D3 A4 B4 C4 D4 Mnemonic SD PGND CF2 HI-Z PVDD CF1 CPVSS GAIN OUTL CPVDD SGND OUTR INL− INL+ INR+ INR− Description Shutdown Control Power Ground Charge Pump Flying Capacitor, Terminal 2 Output Impedance Select Power Supply Charge Pump Flying Capacitor, Terminal 1 Charge Pump Negative Supply Gain Control Left Channel Headphone Output Charge Pump Positive Supply Headphone Sense Ground Right Channel Headphone Output Left Channel Inverting Input Left Channel Noninverting Input Right Channel Noninverting Input Right Channel Inverting Input Rev. 0 | Page 6 of 16 10360-002 D Data Sheet SSM2932 TYPICAL PERFORMANCE CHARACTERISTICS 100 100 IN PHASE OUT OF PHASE 10 10 1 1 THD + N (%) 0.1 100 0.001 0.1 10360-003 1 10 OUTPUT POWER PER CHANNEL (mW) Figure 3. THD + N vs. Output Power, PVDD = 3.6 V, RL = 32 Ω 100 IN PHASE OUT OF PHASE 10 10 1 1 THD + N (%) 0.1 0.01 0.1 0.01 100 0.001 0.1 10360-030 1 10 OUTPUT POWER PER CHANNEL (mW) Figure 4. THD + N vs. Output Power, PVDD = 3.0 V, RL = 32 Ω 100 Figure 7. THD + N vs. Output Power, PVDD = 3.0 V, RL = 16 Ω 100 100 IN PHASE OUT OF PHASE IN PHASE OUT OF PHASE 10 1 1 THD + N (%) 10 0.1 0.1 0.01 0.01 1 10 OUTPUT POWER PER CHANNEL (mW) 100 0.001 0.1 10360-005 THD + N (%) 1 10 OUTPUT POWER PER CHANNEL (mW) 10360-029 THD + N (%) IN PHASE OUT OF PHASE 0.001 0.1 100 Figure 6. THD + N vs. Output Power, PVDD = 3.6 V, RL = 16 Ω 100 0.001 0.1 1 10 OUTPUT POWER PER CHANNEL (mW) 10360-004 0.01 0.01 0.001 0.1 0.1 Figure 5. THD + N vs. Output Power, PVDD = 2.5 V, RL = 32 Ω 1 10 OUTPUT POWER PER CHANNEL (mW) 100 Figure 8. THD + N vs. Output Power, PVDD = 2.5 V, RL = 16 Ω Rev. 0 | Page 7 of 16 10360-006 THD + N (%) IN PHASE OUT OF PHASE SSM2932 Data Sheet 1 1 PO = 5mW PO = 10mW PO = 20mW PO = 5mW PO = 10mW PO = 20mW THD + N (%) 0.1 THD + N (%) 0.1 0.01 100 1k FREQUENCY (Hz) 10k 100k 0.001 10 10360-007 0.001 10 Figure 9. THD + N vs. Frequency, PVDD = 3.6 V, RL = 32 Ω 100 1k FREQUENCY (Hz) 10k 100k 10360-008 0.01 Figure 12. THD + N vs. Frequency, PVDD = 3.6 V, RL = 16 Ω 1 1 PO = 5mW PO = 10mW PO = 20mW PO = 5mW PO = 10mW PO = 20mW THD + N (%) 0.1 THD + N (%) 0.1 0.01 100 1k FREQUENCY (Hz) 10k 100k 0.001 10 10360-009 0.001 10 Figure 10. THD + N vs. Frequency, PVDD = 2.5 V, RL = 32 Ω 1k FREQUENCY (Hz) 10k 100k Figure 13. THD + N vs. Frequency, PVDD = 2.5 V, RL = 16 Ω –50 –50 LEFT CHANNEL RIGHT CHANNEL LEFT CHANNEL RIGHT CHANNEL –60 –70 –70 PSRR (dB) –60 –80 –80 –90 –100 10 100 1k FREQUENCY (Hz) 10k 100k –100 10 Figure 11. PSRR vs. Frequency, PVDD = 3.0 V, RL = 32 Ω 100 1k FREQUENCY (Hz) 10k Figure 14. PSRR vs. Frequency, PVDD = 3.0 V, RL = 16 Ω Rev. 0 | Page 8 of 16 100k 10360-012 –90 10360-011 PSRR (dB) 100 10360-010 0.01 Data Sheet SSM2932 210 170 190 TOTAL OUTPUT POWER (mW) TOTAL OUTPUT POWER (mW) 150 THD + N = 10% 130 110 THD + N = 1% 90 170 THD + N = 10% 150 130 110 THD + N = 1% 90 70 70 2.7 2.9 3.1 3.3 SUPPLY VOLTAGE (V) 3.5 30 2.5 10360-013 50 2.5 Figure 15. Output Power vs. Supply Voltage, RL = 32 Ω 2.7 2.9 3.1 3.3 SUPPLY VOLTAGE (V) 10360-014 50 3.5 Figure 18. Output Power vs. Supply Voltage, RL = 16 Ω 100k 0.2 IMPEDANCE (Ω) GAIN (dB) 0.1 0 10k 1k 100 1k FREQUENCY (Hz) 10k 100k 100 100 10360-015 –75 –60 CHANNEL SEPARATION (dB) CHANNEL SEPARATION (dB) 1M 10M –55 RIGHT TO LEFT LEFT TO RIGHT –85 –90 –95 –100 –105 –110 RIGHT TO LEFT LEFT TO RIGHT –65 –70 –75 –80 –85 –90 100 1k FREQUENCY (Hz) 10k 100k 10360-017 –115 10 10k 100k FREQUENCY (Hz) Figure 19. High-Z Mode Output Impedance vs. Frequency Figure 16. Frequency Response, PVDD = 3.0 V –80 1k –95 10 100 1k FREQUENCY (Hz) 10k 100k 10360-018 –0.2 10 10360-016 –0.1 Figure 20. Channel Separation vs. Frequency, PVDD = 3.0 V, RL = 16 Ω Figure 17. Channel Separation vs. Frequency, PVDD = 3.0 V, RL = 32 Ω Rev. 0 | Page 9 of 16 SSM2932 Data Sheet 250 350 POWER CONSUMPTION (mW) POWER CONSUMPTION (mW) 300 200 150 100 50 250 200 150 100 0 20 40 60 TOTAL OUTPUT POWER (mW) 80 100 0 10360-020 0 Figure 21. Power Consumption vs. Output Power, PVDD = 3.0 V, RL = 32 Ω 0 20 40 60 TOTAL OUTPUT POWER (mW) 80 100 10360-022 50 Figure 24. Power Consumption vs. Output Power, PVDD = 3.0 V, RL = 16 Ω 140 250 POWER DISSIPATION (mW) POWER DISSIPATION (mW) 120 100 80 60 40 200 150 100 50 0 20 40 60 TOTAL OUTPUT POWER (mW) 80 100 0 10360-021 0 Figure 22. Power Dissipation vs. Output Power, PVDD = 3.0 V, RL = 32 Ω 20 40 60 TOTAL OUTPUT POWER (mW) 80 100 Figure 25. Power Dissipation vs. Output Power, PVDD = 3.0 V, RL = 16 Ω 100 1.72 PVDD = 2.5V PVDD = 3.3V QUIESCENT CURRENT (mA) 1.70 10 RL = 32Ω RL = 16Ω 1.68 1.66 1.64 1 10 100 LOAD RESISTANCE (Ω) 1k 1.60 2.5 Figure 23. Maximum Output Power per Channel vs. Load Resistance, Flying Capacitor = 1 μF, THD + N = 1% Rev. 0 | Page 10 of 16 2.7 2.9 3.1 3.3 SUPPLY VOLTAGE (V) Figure 26. Quiescent Current vs. Supply Voltage 3.5 10360-019 1.62 10360-024 OUTPUT POWER PER CHANNEL (mW) 0 10360-023 20 Data Sheet SSM2932 1 500mV/ 2 1.00V/ 3 4 20.00ms 5.00ms Trig’d? 1 1.00V/ 2 1.00V/ 3 2 1.75V 4 1.520ms 2.000ms Trig’d? 1 1.01V T T 1, 2 10360-026 10360-027 1, 2 Figure 27. Start-Up Waveform vs. Time Figure 29. Shutdown Waveform vs. Time 0 –20 OUTPUT (dBV) –40 –60 –80 –100 –120 –140 –180 10 100 1k FREQUENCY (Hz) 10k 100k 10360-028 –160 Figure 28. Output Spectrum vs. Frequency, PVDD = 3.0 V, RL = 32 Ω Rev. 0 | Page 11 of 16 SSM2932 Data Sheet THEORY OF OPERATION The SSM2932 provides a high efficiency Class-G stereo headphone output that is true ground-referenced; therefore, no external coupling capacitors are required for connection to the headphones. The headphones can be connected directly to the headphone output pins, OUTL (Ball A3) and OUTR (Ball D3). The headphone amplifier uses the supply provided at PVDD (Ball A2). This supply voltage must be decoupled with a 1 μF electrolytic capacitor, along with a 100 nF ceramic X7R capacitor. The headphone amplifier uses Class-G architecture and generates the required power supplies with a built-in charge pump that uses a flying capacitor connected across CF1 (Ball B2) and CF2 (Ball C1). The charge pump switching frequency is approximately 54 kHz in the idle state with no input signal detected and 550 kHz when a signal is present. The generated supply voltages are available at CPVDD (Ball B3, positive rail) and CPVSS (Ball C2, negative rail). The supply voltage of the headphone amplifier depends on the input signal to the amplifier. For lower input signal levels, the positive and negative rails are lowered, typically to ±PVDD/2. As the signal level increases, CPVDD and CPVSS are raised to ±2.2 V. This rail switching allows the amplifier to achieve higher efficiency. In most typical usage conditions, the amplifier works on the lower CPVDD and CPVSS voltages (±PVDD/2), thereby consuming less power. In addition, because the amplifier generates the positive and negative rails, the output amplifier is true ground-referenced, thereby eliminating the need for large coupling capacitors to drive the load. For best audio performance, it is recommended that 2.2 μF, X7R ceramic decoupling capacitors be used for CPVDD and CPVSS. These capacitors serve as a reservoir for the headphone amplifier. The headphone amplifier has built-in short-circuit protection and, therefore, shuts down in the event of a short circuit on the headphone outputs. The amplifier is designed to drive headphones with a minimum impedance of 16 Ω. Capacitive loads of up to 150 pF are supported. AMPLIFIER GAIN The SSM2932 amplifier gain can be set to either 0 dB or 6 dB by applying the appropriate logic level to the GAIN pin (see Table 6). Table 6. Amplifier Gain and GAIN Pin Logic Levels Amplifier Gain 0 dB 6 dB GAIN Pin Logic Level Low (≤0.5 V) High (≥1.2 V) AMPLIFIER SHUTDOWN Shutdown of the SSM2932 amplifier is controlled by the SD pin. If a logic low is applied to this pin, the amplifier becomes inactive and draws only minimal current from the supply. Table 7. Amplifier Shutdown Amplifier State Shutdown Power-On SD Pin Logic Level Low (≤0.5 V) High (≥1.2 V) HIGH OUTPUT IMPEDANCE The SSM2932 has a HI-Z control pin that mutes the amplifier and sets the output to a high impedance. If both HI-Z and SD are set high, the amplifier remains in a high impedance state. This feature allows the headphone output jack to be shared for other functions such as video output or data transmission. GROUND SENSE SGND (Ball C3) is provided for sensing the dc potential at the headphone jack. It is recommended that SGND be connected directly to the ground pin of the headphone jack to ensure the lowest dc offset at the amplifier output and to eliminate pop-andclick noises when the amplifier is turned on or off. In addition, connecting the SGND ball directly to the ground pin of the headphone jack helps to reduce crosstalk between the left and right channel outputs. A dc path between the SGND pin and the system ground must also be provided. LAYOUT Care must be taken to lay out PCB traces and wires properly between the amplifier, load, and power supply. A good practice is to use short, wide PCB tracks to decrease voltage drops and minimize inductance. Ensure that track widths are at least 200 mil per inch of track length for lowest DCR, and use at least 1 oz or 2 oz copper thickness to minimize resistance. A poor layout increases voltage drops, consequently affecting efficiency. Use large traces for the power supply inputs and amplifier outputs to minimize losses due to parasitic trace resistance. Proper grounding guidelines help to improve audio performance, minimize crosstalk between channels, and prevent switching noise from coupling into the audio signal. The PCB traces that connect the output pins to the load, as well as the PCB traces to the supply pins, should be as wide as possible to maintain the minimum trace resistances. It is also recommended that a large ground plane be used for minimum impedances. The SGND pin should be connected directly to the ground pin of the headphone jack. Rev. 0 | Page 12 of 16 Data Sheet SSM2932 In addition, good PCB layout isolates critical analog paths from sources of high interference. High frequency circuits (analog and digital) should be separated from low frequency circuits. Properly designed multilayer PCBs can reduce EMI emissions and increase immunity to the RF field by a factor of 10 or more compared with double-sided boards. A multilayer board allows a complete layer to be used for the ground plane, whereas the ground plane side of a double-sided board is often disrupted by signal crossover. If the system has separate analog and digital ground and power planes, the analog ground plane should be directly beneath the analog power plane, and, similarly, the digital ground plane should be directly beneath the digital power plane. There should be no overlap between analog and digital ground planes or between analog and digital power planes. Rev. 0 | Page 13 of 16 SSM2932 Data Sheet TYPICAL APPLICATION CIRCUIT 2.2µF 2.2µF POR GAIN CPVSS CPVDD HI-Z GAIN CF2 SD CF1 1µF POWER MANAGEMENT 100nF PVDD 1µF PGND 0.1µF INL+ 0.1µF OUTR PGA INL– SGND 0.1µF INR+ 0.1µF PHONE JACK OUTL PGA INR– POP/ CLICK CURRENT LIMIT Figure 30. Application Circuit (Differential Input Configuration) Rev. 0 | Page 14 of 16 10360-031 SSM2932 Data Sheet SSM2932 OUTLINE DIMENSIONS 1.680 1.640 SQ 1.600 4 3 2 1 A BALL A1 IDENTIFIER B 1.20 REF C TOP VIEW 0.40 REF (BALL SIDE DOWN) BOTTOM VIEW (BALL SIDE UP) SIDE VIEW COPLANARITY 0.05 0.300 0.260 0.220 SEATING PLANE 0.230 0.200 0.170 02-03-2012-A 0.560 0.500 0.440 D Figure 31. 16-Ball Wafer Level Chip Scale Package [WLCSP] 1.6 mm × 1.6 mm Body (CB-16-11) Dimensions shown in millimeters ORDERING GUIDE Model 1 SSM2932ACBZ-RL SSM2932ACBZ-R7 EVAL-SSM2932Z 1 Temperature Range −40°C to +85°C −40°C to +85°C Package Description 16-Ball Wafer Level Chip Scale Package [WLCSP] 16-Ball Wafer Level Chip Scale Package [WLCSP] Evaluation Board Z = RoHS Compliant Part. Rev. 0 | Page 15 of 16 Package Option CB-16-11 CB-16-11 SSM2932 Data Sheet NOTES ©2012 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D10360-0-2/12(0) Rev. 0 | Page 16 of 16