VA2208TSG28

VA2208 15W Filterless Stereo Class D Audio Amplifier General Description Features The VA2208 is a cost-effective filter-less Class - Operation Voltage from 8V to 26V D stereo audio power amplifier that operates in wide - Maximum 88% Efficiency with an 8Ω Speaker range of various power supplies. VA2208 provide - 15W@8Ω Load with THD+N =10% at 16V volume control with four selectable gain settings - 10W@8Ω Load with THD+N =10% at 13V (20dB, 26dB, 32dB, 36dB). VA2208 can output 15W - Four Selectable Gain Settings per channel into 8Ω load with lower supply current - Scalable Power Limit Function and fewer external components for driving bridged- - Speaker DC Detection and Protection tied stereo speaker directly. With the function of - Parallel BTL Speaker Driving Connection power limit, the speakers could be operated safely - Thermal Protection with Auto-Recovery and the input signal would be also normalized. - Speaker Protection Circuitry - Short Circuit and Thermal Protection - RoHS 2.0 compliant TSSOP-28 Green Pack- VA2208 operates with high efficiency energy conversion up to 88% (8Ω Load) so that the external age with Exposed Pad heat sink can be eliminated while playing music. VA2208 also integrates Anti-Pop, Output Short & Over-Heat Protection Circuitry to ensure device reliability. This device also provides the DC detect and protection scheme to prevent the damage of Applications speaker voice coils. The VA2208 is available in small TSSOP-28 green - LCD TV - Multimedia Speakers - Sound Bar package with exposed pad. Typical Application VA2208 Rev A.01 1 http://www.viva-elec.com.tw VA2208 Functional Block Diagram VA2208 Rev A.01 2 http://www.viva-elec.com.tw VA2208 Pin Assignments And Descriptions Pin No. Pin I/O/P 1 SD_B I 2 FAULT_B O 3 LINP I Left channel positive audio signal input. 4 LINN I Left channel negative audio signal input. 5 GAIN0 I Gain selection least significant bit. 6 GAIN1 I Gain selection most significant bit. 7 AVDD P Analog Power Supply. 8 AGND P Analog Ground. 9 VREG O Regulated Voltage. Nominal voltage is 5.5V. 10 PLIMIT I 11 RINN I Right channel negative audio signal input. 12 RINP I Right channel positive audio signal input. 13 NC - No internal connection. 14 PBTL I Parallel BTL mode switch. 15,16 PVDDR P Right channel power supply. 17 BSPR I Bootstrap I/O for right channel positive high-side switch. 18 ROUTP O Right channel positive output. 19 PVSSR P Right channel power ground. 20 ROUTN O Right channel negative output. 21 BSNR I Bootstrap I/O for right channel negative high-side switch. 22 BSNL I Bootstrap I/O for left channel negative high-side switch. 23 LOUTN O Left channel negative output. 24 PVSSL P Left channel power ground. 25 LOUTP O Left channel positive output. 26 BSPL O Bootstrap I/O for left channel positive high-side switch. 27,28 PVDDL P Left channel power supply. VA2208 Rev A.01 Function Description Shutdown control terminal. Low active. TTL Logic levels with compliance to AVDD. Protection Flag Indicator (Open Drain). Connecting FAULT_B and SD_B can be set to auto-recovery. Otherwise need to reset by cycling AVDD. Power Limit Level Adjust. Connect a resistor divider from VREG to GND to set power limit. Connect to VREG directly for no power limit. 3 http://www.viva-elec.com.tw VA2208 Absolutely Maximum Ratings Over operating free-air temperature range, unless otherwise specified (* 1) Symbol Parameter Limit Unit VDD(PVDDR, PVDDL, AVDD) Supply voltage -0.3 to 30 V Input voltage -0.3 to VDD+0.3 V VI (PLIMIT) Input voltage -0.3 to VREG+0.3 V VI (LINN, RINN, LINP, RINP) Input voltage -0.3 to 6.5 V TA Operating free-air temperature range -40 ~ +85 o C TJ Operating junction temperature range(* 2) -40 to +150 o C TSTG Storage temperature range -65 to 150 o C R(LOAD) Minimum load resistance θJC Thermal Resistance (Junction to Case) 8 o C/W θJA Thermal Resistance (Junction to Air) 45 o C/W Electrostatic discharge Human body model ±2 kV Electrostatic discharge Machine model ±200 V VI (GAIN0, GAIN1, PBTL, FALUT_B, SD_B) 8 (VDD>15V) Ω 4 (VDD≤15V) ( *1): Stress beyond those listed at “absolute maximum rating” table may cause permanent damage to the device. These are stress rating ONLY. For functional operation are strongly recommend follow up “recommended operation conditions” table. Recommended Operating Conditions Over operating free-air temperature range, unless otherwise specified. Symbol Parameter Test Condition VDD Supply voltage VIH VIL VOL TA Min Max PVDDL, PVDDR, AVDD 8 26 VDD=24V 2 High level input voltage (GAIN0, GAIN1, PBTL, SD_B) Low level input voltage VA2208 Rev A.01 Unit V V VDD=24V 0.8 V VDD=24V, RPULL-HIGH=100kΩ 0.8 V (GAIN0, GAIN1, PBTL, SD_B) Low level output voltage (FAULT_B) Operating free-air temperature Specification -40 4 85 o C http://www.viva-elec.com.tw VA2208 Electrical Characteristics TA = 25℃, VDD = 12V, RL=8Ω, GAIN=20dB, unless otherwise noted. Symbol |VOS| Parameter Specification Test Condition Output offset voltage (measured differentially) Min Unit Typ. Max VI=0V 1.5 15 mV IQ Quiescent current SD_B=2V, No load, w/o L/C 25 40 mA ISD Shutdown current SD_B=0.4V, No load 300 450 µA tON Shutdown turn-on time SD_B=2V 20 ms tOFF Shutdown turn-off time SD_B=0.8V 2 µs fOSC Internal oscillation frequency 260 kHz A Amplifier gain RDS(ON) Drain-Source ON resistance1 VREG Regulator output tDC-DET DC detect time GAIN1=0.8V, GAIN0=0.8V 20 GAIN1=0.8V, GAIN0=2V 26 GAIN1=2V, GAIN0=0.8V 32 GAIN1=2V, GAIN0=2V 36 VDD=12V, High Side 240 IOUT=500mA Low Side 240 IVREG = 100µA, VDD=8~25V 5.25 5.5 dB mΩ 5.75 450 V ms (1) Design center value. Electrical Characteristics TA = 25℃, VDD = 24V, RL=8Ω, GAIN=20dB, unless otherwise noted. Symbol |VOS| Parameter Specification Test Condition Output offset voltage (measured differentially) Min Unit Typ. Max VI=0V 1.5 15 mV IQ Quiescent current SD_B=2V, No load, w/o L/C 35 50 mA ISD Shutdown current SD_B=0.4V, No load 350 500 µA tON Shutdown turn-on time SD_B=2V 20 ms tOFF Shutdown turn-off time SD_B=0.8V 2 µs fOSC Internal oscillation frequency 260 kHz A Amplifier gain RDS(ON) Drain-Source ON resistance1 VREG Regulator output tDC-DET DC detect time GAIN1=0.8V, GAIN0=0.8V 20 GAIN1=0.8V, GAIN0=2V 26 GAIN1=2V, GAIN0=0.8V 32 GAIN1=2V, GAIN0=2V 36 VDD=12V, High Side 240 IOUT=500mA Low Side 240 IVREG = 100µA, VDD=8~25V 5.25 5.5 450 dB mΩ 5.75 V ms (1) Design center value. VA2208 Rev A.01 5 http://www.viva-elec.com.tw VA2208 Operating Characteristics VDD=12V, AV=20dB, TA = 25℃ unless otherwise noted. Specification Symbol Parameter Test Condition PO Output power Total harmonic distortion plus noise Supply ripple rejection ration THD+N=10%, f=1kHz, RL=8Ω, VDD=13V THD+N |KSVR| |SNR| Vn Signal-to-Noise ratio Min Typ. Max Unit 10 W 0.07 % Input AC-Grounded, Ci=1µF, f=1kHz 70 dB A-weighted, THD+N=1%, RL=8Ω 97 dB VDD=12V, PO=5W, RL=8Ω, f=1kHz VDD=12V, f=20Hz to Output voltage noise 20kHz, Input ACGrounded, Ci=1µF No Weight 100 µVRMS A-Weighted 80 f=120Hz 66 dB 102 dB |CMRR| Common mode rejection ratio VDD=12V, VIC=1VPP Crosstalk Channel separation VO=1W, f=1kHz, Gain=20dB Operating Characteristics VDD=24V, AV=20dB, TA = 25℃ unless otherwise noted. Specification Symbol Parameter Test Condition PO Output power Total harmonic distortion plus noise Supply ripple rejection ration THD+N=10%, f=1kHz, RL=8Ω, VDD=16V THD+N |KSVR| |SNR| Vn Signal-to-Noise ratio Typ. Max Unit 15 W 0.08 % Input AC-Grounded, Ci=1µF, f=1kHz 68 dB A-weighted, THD+N=1%, RL=8Ω 99 dB VDD=24V, PO=10W, RL=8Ω, f=1kHz VDD=12V, f=20Hz to Output voltage noise 20kHz, Input ACGrounded, Ci=1µF No Weight µVRMS 80 f=120Hz 66 dB 101 dB Common mode rejection ratio VDD=12V, VIC=1VPP Crosstalk Channel separation VO=1W, f=1kHz, Gain=20dB 6 100 A-Weighted |CMRR| VA2208 Rev A.01 Min http://www.viva-elec.com.tw VA2208 Functional Descriptions Gain Settings ter, the cut-off frequency fo may vary with the change of gain setting. The -3dB point of the cutoff frequency can be calculated by the following The gain of the VA2208 can be set by GAIN0 and equation, GAIN1 pins. The gain ratios listed in Table 1 are implemented by changing the taps on the feedback (Hz) Equation (2) resistors in the preamplifier stage. ,where the RI values is given in Table 1. The input resistance is depended on the gain setting. Since the gain setting is determined by the Shutdown Operation ratio of the internal feedback resistive network, the variation of the gain is small. But the absolute value of the input resistance may shift by ±20% at the The VA2208 employs a state of shutdown mode to same gain. In actual design cases, 80% of nominal reduce supply current to the absolute minimum value should be assumed as the input resistance of level during periods of nonuse for power conser- VA2208 in the input network of whole amplifier. vation. This terminal should be held high during normal operation when the amplifier is in normal Gain Gain Gain 1 0 Ratio 1 1 1 operating. Pulling low causes the output drivers Resistance Range shutdown and the amplifier to enter a low-current 36dB 9kΩ 7.2kΩ~10.8kΩ state. Do not leave it unconnected, because there is 0 32dB 15kΩ 12kΩ~18kΩ 0 1 26dB 30kΩ 24kΩ~36kΩ 0 0 20dB 60kΩ 48kΩ~72kΩ no weakly pulling resistor inside the amplifier. Remember that to place the amplifier in the shutdown state prior to removing the power supply voltage so that power-off pop noise can be elimi- Table 1. Gain Setting nated. Amplifier Input Impedance VREG Supply The VREG Supply is used to bias the gates of the output full-bridge upper half MOSFETs. It could be used to supply the PLIMIT pin and related voltage divider circuit. Add at least 1µF capacitor to ground at this pin. Speaker Protection Figure 1. Cut-off Point of High-pass Filter Due to the nature of Class D amplifiers, the In most cases, no extra resistor needs to be added speakers may have DC current if the audio inputs on the input of VA2208. The actual input resistor get DC voltage in any case. An output DC fault will is already determined while selecting the gain. If a make FAULT_B pin in low state and shuts down the single capacitor is used in the input high-pass fil- audio amplifier and change the state of output into VA2208 Rev A.01 7 http://www.viva-elec.com.tw VA2208 Functional Descriptions (cont.) high impedance. ground. To resolve the case of DC input, it is good to treat it Short Circuit Protection as very low frequency sine wave much lower than audio band such as 2Hz. Based on this criteria, a DC VA2208 has protection from over-current condi- detect fault shall be issued when the output dif- tions caused by a short circuit on the output stage. ferential duty-cycle of either channel exceeds 14% The short circuit protection fault is reported on the for more than 500ms at the same polarity. This FAULT_B pin as a low state. The amplifier outputs feature protects the speakers away from large cur- are switched to a high impedance state when the rents. short circuit protection latch is engaged. The latch can be cleared by cycling the SD_B pin through the The minimum differential input DC voltages re- low state. quired to trigger the DC detection fault are listed in Table 2. Connect FAULT_B to SD_B pin, the over current protection will be auto recovery. AV (dB) VIN (mV, Differential) 36 17 32 28 26 56 20 112 Thermal Protection Thermal protection on the VA2208 prevents damage to the device when the internal die temperature exceeds 160°C. There is a ±20°C tolerance on this trip point from device to device. Once the die Table 2. DC detect fault threshold temperature exceeds the thermal set point, the To resume the normal operation, it is necessary to device enters into the shutdown state and the power off the amplifier and then power on, cycling outputs are disabled. This is not a latched fault. SD_B can not resume normal operation. The thermal fault is cleared once the temperature of the die is reduced by 50°C. VA2208 will be back Parallel BTL Mode for Mono Operation to normal operation at this point with no external system interaction. VA2208 offers the feature of Stereo operation with two outputs of each channel connected directly. If Thermal protection fault will not be reported on the the PBTL pin (pin 14) is tied high, the positive and FAULT_B terminal. negative outputs of each channel (left and right) are synchronized and in phase. To operate in this Power Limit Operation mono mode, apply the input signal to the RIGHT input and place the speaker between the LEFT and The voltage at PLIMIT terminal (pin 10) can be used RIGHT outputs. Connect the positive and negative to limit the power to levels below that which is output together for best efficiency. Parallel BTL possible based on the supply rail. Add a resistor mode can increase more output power compare divider from VREG to ground to set the voltage at to the stereo mode single channel’s output power. the PLIMIT terminal. An external reference may also For normal BTL operation, connect the PBTL pin to VA2208 Rev A.01 be used if precise limitation is required. Also add a 8 http://www.viva-elec.com.tw VA2208 Functional Descriptions (cont.) 1•F capacitor from this pin to ground. The PLIMIT circuit sets a limit on the output peak-to -peak voltage. The limiting is done by limiting the duty cycle to fixed maximum value. This limit can be thought of as a “virtual” voltage rail which is lower than the supply connected to power rail. This “virtual” rail is about 5.2 times the voltage at the PLIMIT pin. This output voltage can be used to calculate the maximum output power for a given Figure 2. PLIMIT Pin Voltage Divider maximum input voltage and speaker impedance. Use the simple voltage divider to determine the voltage on PLIMIT pin from VREG pin by the following equation: where RS is the total series resistance including (ON) RDS and any resistance in the output filter. RL is the In order to maintain the regulation of VREG pin load resistance. VP is the peak amplifier of the out- well please apply higher resistor value such as put possible within the supply rail. 10kΩ on low side resistor but should not exceed 50kΩ. Po@THD+N (W) VDD(V) RL(Ω) PLIMIT(V) 12 8 0.93 12 8 1.107 1.923 1.452 12 8 1.33 2.955 2.118 10% 1% 1.328 1.005 12 8 1.434 3.527 2.536 24 (Heat Sink) 8 1.612 3.746 2.994 24 (Heat Sink) 8 1.899 5.267 3.999 24 (Heat Sink) 8 2.238 7.069 5.677 24 (Heat Sink) 8 2.683 10.77 8.299 12 4 0.89 1.972 1.518 12 4 1.117 3.123 2.406 12 4 1.285 4.144 3.175 12 4 1.408 5.007 3.839 Table 3. PLIMIT value vs. Output Power Due to the VREG driving ability limitation, it is not recommended to use this pin to drive other circuits except PLIMIT resistor network. The recommended resistor network is shown on Figure 2. VA2208 Rev A.01 9 http://www.viva-elec.com.tw VA2208 Application Information Output Filter Design the VA2208 without the filter if the traces from amplifier to speaker are short (< 10cm), where the speaker is in the same enclosure as the amplifier is a typical application for class D without a filter. Many applications require a ferrite bead filter at least. The ferrite filter reduces EMI above 30MHz. Figure 5. Typical Ferrite Chip Bead Output Filter, When selecting a ferrite bead, choose one with high Speaker Impedance=8Ω impedance at high frequencies, but low impedance at low frequencies, be aware of its maximum cur- Inductors used in LC filters must be selected care- rent limitation. fully. A significant change in inductance at the peak output current of the VA2208 will cause increased Use an LC output filter if there are low frequency distortion. The change of inductance at currents up (