BA Features. General Description. Applications. Marking Information. 3W Mono Filterless Class D Audio Power Amplifier

Transcription

1 3W Mono Filterless Class D Audio Power Amplifier General Description The BA16853 is a cost-effective mono Class D audio power amplifier that assembles in Dual Flat No-Lead Plastic Package (DFN-8). Only three external components offer space and cost saving for cellular phone, PDA, or toy application. The BA16853 provides 3W high performance output capacity at 4-Ω load. Other features like 89% efficiency, -75dB PSRR, fully differential design reduces RF interference, and allows independent gain while summing signals from various audio sources. BA16853 also integrates Anti-Pop, Output Short & Over-Heat Protection Circuitry to increase device reliability. Such functionalities make this device ideal for cellular phone, PDA, Features 1.3W into 8-Ω Speaker (THDN = 1%@5V) 2.3W into 4-Ω Speaker (THDN = 1%@5V) Operation Voltage From 2.5 To 5.5V Shutdown Current <1μA PSRR, -75dB 89% Efficiency into 8-Ω, 1.3W output 80% Efficiency into 8-Ω, 0.25W output 30ms Start-up time eliminates pop-noise Filter-Free PWM Output without LC Filter Integrated Output Short Protection Circuitry Integrated Over-Heat Protection Circuitry Fully differential input eliminates coupling capacitors and reduces RF interference Standard TDFN-8 Package with exposed pad RoHS Standard Compliant toy and other applications that demand more battery life. Marking Information Applications Battery Powered Application Cellular Phone 1 2 (Date Code) For date code rule, please contact our sales representative directly. Portable Navigation Device Portable Electronic Device 3 4 (Internal Code) Rev01-1 -

2 Typical Application Filter-free application with differential input Internal Oscillator VDD To Power Source C S - INN Audio Input PWM Driver INP SD_B Bias Circuitry GND BA16853 Functional Block Diagram VDD INP 200K Data Processor Output Driver INN 200K - SD_B Shutdown Control 300K Bias & References Clock Generator Startup Protection OC Detect GND Rev01-2 -

3 Pin Configurations TDFN-8 (3x3mm) SD_B 1 8 NC INP 2 3 EXPOSED PAD ON THE BACKSIDE 7 6 GND VDD INN 4 (GND) 5 Pin No. Name Description 1 SD_B Shutdown (Active Low Logic). 2 NC No connection. 3 INP Positive differential audio input. 4 INN Negative differential audio input. 5 Positive BTL output. 6 VDD Power supply. 7 GND Power Ground. 8 Negative BTL output. Absolute Maximum Ratings Parameter Supply Voltage Range VDD Rating -0.3V ~ 6V Input Voltage Range VIN Operating Free-Air Temperature Range TA Operating Junction Temperature Range TJ -0.3V ~ V DD 0.3V -40 o C ~ 85 o C -40 o C ~ 125 o C Storage Temperature Range TSTG -65 C ~ 150 C 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. Rev01-3 -

4 Recommended Operating Conditions Parameter Rating Supply Voltage, VDD 2.5V ~ 5.5V High Level Input Voltage, VIH Low Level Input Voltage, VIL Input Resistor, RIN PWM Frequency, fpwm Common Mode Input Voltage Range, VIC Operating Free-Air Temperature Range, TA 2V (SD_B) 0.4V (SD_B) 15kΩ min 250kHz ~ 300kHz 0.5V ~ VDD-0.8V -40 o C ~ 85 o C These are conditions under which the device functions but the specifications might not be guaranteed. For guaranteed specifications and test conditions, please see the Electrical Characteristics. Electrical Characteristics T A =25ºC, unless otherwise noted. Parameter Test Condition Min. Typ. Max. Units Output Offset Voltage, VOS V I = 0V, A V = 2V/V, V DD = 2.5 to 5.5V 1 25 mv Power Supply Rejection Ratio, PSRR V DD = 2.5 to 5.5V db Common Mode Rejection Ratio, CMRR V DD = 2.5 to 5.5V, V IC = 0.5V to V DD-0.8V db Quiescent Current, IQ VDD=5V VDD=3.6V ma High Level Input Current, IIH V DD = 5.5V, V I = 5.8V 100 μa Low Level Input Current, IIL V DD = 5.5V, V I = -0.3V 5 μa Switching Frequency, FSW V DD = 2.5 to 5.5V khz Shutdown Current, ISD V (SHUTDOWN_B) = 0.35V, V DD = 2.5 to 5.5V ua Static Drain-Source On State Resistance, rds(on) High Side, VDD=5V, ID=500mA, Low Side, VDD=5V, ID=500mA mω Gain, GAIN VDD=2.5V ~ 5.5V 375kΩ 400kΩ 425kΩ V/V Resistance from SD_B to GND 300 kω Rev01-4 -

5 Operating Characteristics T A =25ºC, GAIN=2V/V, RL=3/4/8Ω, unless otherwise noted. Parameter Test Condition Min. Typ. Max. Units Output Power, PO THDN = 10% f = 1KHz, R L = 3Ω THDN = 1% f = 1KHz, R L = 3Ω THDN = 10% f = 1KHz, R L = 4Ω THDN = 1% f = 1KHz, R L = 4Ω THDN = 10% f = 1KHz, R L = 8Ω THDN = 1% f = 1KHz, R L = 8Ω V DD = 5V 3.56 V DD = 3.6V 1.77 V DD = 2.5V 0.68 V DD = 5V 2.77 V DD = 3.6V 1.28 V DD = 2.5V 0.55 V DD = 5V 2.98 V DD = 3.6V 1.48 V DD = 2.5V 0.65 V DD = 5V 2.28 V DD = 3.6V 1.08 V DD = 2.5V 0.47 V DD = 5V 1.68 V DD = 3.6V 0.88 V DD = 2.5V 0.40 V DD = 5V 1.32 V DD = 3.6V 0.64 V DD = 2.5V 0.30 V DD = 5V, P O = 1W, R L = 8Ω, f = 1KHz 0.2 Total Harmonic Distortion plus Noise, V DD = 3.6V, P O = 0.5W, R L = 8Ω, f = 1KHz 0.17 THDN V DD = 3.0V, P O = 0.2W, R L = 8Ω, f = 1KHz 0.27 W W W W % Supply Ripple Rejection Ratio, ksvr V DD = 3.6V Input AC-Grounded C i = 2µF f = 215Hz V (RIPPLE) = 0.2V PP -67 db Signal to Noise Ratio, SNR V DD = 5V, P O = 1W, R L = 8Ω 93 db Output Noise Voltage, Vn Common Mode Rejection Ratio, CMRR V DD = 3.6V f = 20Hz to 20KHz Input AC-Grounded C i = 2µF V DD = 3.6V V IC = 1V PP No Weight 88 A-Weighted 63 µv RMS f = 217Hz -63 db Input Impedance, ZI kω Start-up Time from Shutdown, TSTART V DD = 3.6V 30 ms Rev01-5 -

6 Measuring Environment C I INP AP (Analog Generator) - C I INN BA16853 Performance Testing Board Load AP AUX AP (Analog Analyzer) 1µF Power Supply Notes: 1. C I was shorted for any Common-Mode input voltage measurement. 2. A 22µH inductor was placed in series with the load resistor to emulate a small speaker for efficiency measurement. 3. The AP AUX-0025 low-pass filter is required. 4. The 22-KHz or 30-KHz low-pass filter is required even if the AP analyzer has an internal low-pass filter. Typical Performance Characteristics Efficiency vs. Output Efficiency vs. Output Rev01-6 -

7 Typical Performance Characteristics (Contd.) Power Dissipation vs. Output Power Dissipation vs. Output Supply Current vs. Output Rev01-7 -

8 Typical Performance Characteristics (Contd.) Quiescent Current vs. Supply Range Shutdown Current vs. Shutdown Voltage Output Power at 1% THDN vs. Load Resistance Rev01-8 -

9 Typical Performance Characteristics (Contd.) Output Power at 10% THDN vs. Load Resistance Output Power vs. Supply Voltge THDN vs. Supply Rev01-9 -

10 Typical Performance Characteristics (Contd.) THDN vs. Supply THDN vs. Supply THDN vs. Frequency Rev

11 Typical Performance Characteristics (Contd.) THDN vs. Frequency THDN vs. load,250mw output THDN vs. Frequency Rev

12 Typical Performance Characteristics (Contd.) THDN vs. Frequency THDN vs. Frequency THDN vs. load,250mw output Rev

13 Typical Performance Characteristics (Contd.) Supply Ripple Rejction Ratio vs. Supply Ripple Rejction Ratio vs. Supply Ripple Rejction Ratio vs. Frequency at Input Floating Rev

14 Application Information General Information The basic structure of BA16853 is a Class D amplifier with differential inputs and BTL output. The BA16853 has one differential amplifier and one common-mode amplifier inside. The differential amplifier output a differential voltage that is equal to the differential input times the gain. The common-mode feedback ensures that the common-mode voltage at the output is biased around V DD /2 regardless of the common-mode voltage at the input. The BA16853 can still be used with a single ended input. The BA16853 should be used with differential inputs when in a noisy environment, like a wireless handset, to ensure maximum noise rejection. Input Resistance (RI) The gain of BA16853 can be set by external resistors shown in Figure 1. Set the gain of the amplifier according to Equation (1) 2 200kΩ Gain = (V/V) (1) The gain should be set to 2 V/V or lower for best performance. Lower gain implies the BA16853 use a higher amplitude signal input and make the input less susceptible to noise. 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. It is recommended to use 1% tolerance resistor or better for best performance. Matching is more important than overall tolerance. Resistor arrays with 1% matching can be used with a tolerance greater than 1%. The resistor should be placed close to the BA16853 and keep the input traces close to each other with the same length in high noise environment. It can limit noise injection on the high-impedance nodes. Power Supply Decoupling Capacitor (CS) As with any power amplifier, proper power supply decoupling capacitor is critical for low noise performance and high power supply rejection ration (PSRR). A good low equivalent-series-resistance (ESR) ceramic capacitor, typically 1µF, placed as close as possible to the device V DD lead works best. Placing this decoupling capacitor close to the BA16853 is very important for the efficiency of the class-d amplifier, because any resistance or inductance in the trace between the device and capacitor can cause a loss in efficiency. Rev

15 Input Capacitor (CI) The input capacitor may be needed for some applications or when the source is single-ended (See Figure 28). This capacitor can block the DC voltage at the amplifier input terminal and create a high-pass filter with the input resistor. The cut-off frequency of high-pass filter is according to Equation (2) f C = 1 2 π R C (Hz) (2) I I The value of the input capacitor affects the low frequency performance of the circuit directly. Speakers in wireless phone can t respond well to low frequency, so the cut-off frequency can be set to block low frequency in this application. For example, power supply noise is at 217Hz in a GSM phone. Setting cut-off frequency of high-pass filter above 217Hz can filter out this noise that it is not amplified and heard on the output. Capacitor has 10% tolerance or better is recommended for impedance matching. Differential Circuit Configurations The BA16853 can be used in many different circuit configurations. The simplest and best performing is the DC-coupled, differential input configuration show in Figure 1. The resistor can set the amplifier output gain. Set the gain of the amplifier according to Equation (1). The input capacitors can be used in a differential configure as show in Figure 2. The input capacitor C I with input resistor can create a high-pass filter. The cut-off frequency of high-pass filter is according to Equation (2). Equation (1) above is used to determine the value of the resistors for a desired gain. The BA16853 can be used to amplify more than one audio source. Figure 3 shows a dual differential input configuration. The gain for each input source can be set independently according to Equation (3) and (4) kΩ Gain 1 = (V/V) (3) kΩ Gain 2 = (V/V) (4) 2 The input capacitors can be used with one or more input source as well to have different frequency responses depending on the source or if a DC voltage needs to be blocked from the source. Rev

16 Differential Input INN Internal Osciliator VDD To Power Source C S PWM Driver INP SD_B Bias Circuitry GND Shutdown Control BA16853 Figure 1. Differential Input Configuration Differential Input C I INN Internal Osciliator VDD To Power Source C S PWM Driver C I INP SD_B Bias Circuitry GND Shutdown Control BA16853 Figure 2. Differential Input Configuration with Input Capacitors Differential Input Differential Input 2 2 INN Internal Osciliator VDD To Power Source C S PWM Driver 2 INP SD_B Bias Circuitry GND Shutdown Control BA16853 Figure 3. Dual Differential Input Configuration Rev

17 Single-Ended Circuit Configurations The BA16853 can also be used with single-ended sources, but input capacitors will be needed to block any DC at the input terminals. The typical single-ended application configuration is shown in Figure 4. The equation of gain is Equation (1) and the equation of frequency response is Equation (2), hold for the single-ended configuration as shown in Figure 4. When using more than one single-ended source as shown in Figure 5. The gain and cut-off frequency (f C1 and f C2 ) for each input source can be set independently, shows in Equation (5) ~ Equation (8). Resistor, 3, and capacitor, C I3, are needed on the INP terminal to match the impedance on the INN terminal. Equation (9) and Equation (10) shows how to calculate C I3 and 3 value. The single-ended inputs must be driven by low impedance source even if one of the inputs does not output any AC signal kΩ Gain 1 = (V/V) (5) kΩ Gain 2 = (V/V) (6) 2 f C1 = 1 2 π R C (Hz) (7) I1 I1 f C2 = 1 2 π R C (Hz) (8) I2 I2 C = C C (9) I3 I1 I2 R I3 = ( 1 R I1 1 1 R I2 R = ) R I1 I1 R R I2 I2 (10) Single-Ended Input C I INN Internal Osciliator VDD To Power Source C S C I INP PWM Driver SD_B Bias Circuitry GND Shutdown Control BA16853 Figure 4. Single-Ended Input Configuration Rev

18 Single-Ended Input 1 C I1 1 Single-Ended Input 2 C I2 2 INN Internal Osciliator VDD To Power Source C S C I3 3 INP PWM Driver SD_B Bias Circuitry GND Shutdown Control BA16853 Figure 5. Dual Single-Ended Input Configuration Combine Single-Ended and Differential Input Configurations A typical application with one single-ended source and one differential source shows in Figure 6. Ground noise will disturb input signal within INP terminal by using this configuration. It is better to use dual differential inputs. The cut-off frequency of the single-ended input is set by C I is shown in Equation (13). To assure that all inputs are balanced with each other, the single-ended input must be driven by a low-impedance source even if the input is not in use kΩ Gain 1 = (V/V) (11) kΩ Gain 2 = (V/V) (12) f C2 2 = 1 2 π R C (Hz) (13) I2 I Rev

19 Differential Input Single-Ended Input 2 C I 2 INN Internal Osciliator VDD To Power Source C S C I 2 INP PWM Driver SD_B Bias Circuitry GND Shutdown Control BA16853 Figure 6. Dual Input with a Single-Ended Input and a Differential Input Configuration Shutdown Mode The BA16853 provides a shutdown mode for reduce supply current to the absolute minimum level during periods of nonuse for battery-power conservation. The BA16853 has an internal 300kΩ resistor connected between GND and SD_B pins. The purpose of this resistor is to eliminate any unwanted state changes when shutdown pin is floating. The SD_B input pin should be held high during normal operation when the amplifier is in use. Pulling SD_B low or left floating causes the outputs to mute and the amplifier to enter a low-current state. During the shutdown mode, the DC quiescent current of the circuit does not exceed 0.5µA. Output Filter Configurations Design the BA16853 without the filter if the traces from amplifier to speaker are short (<100mm) when the speaker is in the same enclosure as the amplifier. This configuration is a typical application for class D portable application. Like wireless handsets and PDAs are applications for class D without a filter. Many applications require a ferrite bead filter. The ferrite filter reduces EMI around 30 MHz. When selecting a ferrite bead, choose one with high impedance at high frequencies, but low impedance at low frequencies. Use an LC output filter if there are low frequency (<1 MHz) EMI sensitive circuits and there are long wires (>1.5 m) from the amplifier to the speaker. Rev

20 Figure 7 & 8 show typical LC and ferrite bead output filters. 22µH 0.1µF 22µH 0.47µF 0.1µF Figure 7. Typical LC Output Filter BEAD (600R) 470pF BEAD (600R) 330pF 330pF Figure 8. Typical Ferrite Chip Bead Output Filter (Chip bead example: Queen Core / TI321611U601) Board Layout Considerations Place all the external components very close to the BA Placing the decoupling capacitor, C S, close to the BA16853 V DD terminal is very important for the efficiency of the class-d amplifier. Any resistance and inductance in the trace between the device and the capacitor can cause a loss in efficiency. Additionally, the input resistors need to be very close to the BA16853 input terminal, so noise does not couple on the high-impedance nodes between the input resistors and the input amplifier of the BA Rev

21 Package Outline TDFN-8 with Exposed Pad SYMBOL DIMESION (MM) DIMESION (MIL) MIN. NOM. MAX. MIN. NOM. MAX. A A A REF 8 REF b D D E E L 0.35 BASIC 13.8 BASIC e BASIC 25.6 BASIC e BASIC 76.8 BASIC y Rev

22 NOTICE The specifications and product information of INNO-TECH Co., Ltd. are subject to change without any prior notice, and customer should contact INNO-TECH Co., Ltd. to obtain the latest relevant information before placing orders and verify that such information is current and complete. The information provided here is believed to be reliable and accurate; however INNO-TECH Co., Ltd. makes no guarantee for any errors that appear in this document. LIFE SUPPORT POLICY INNO-TECH products are not designed or authorized for use as critical components in life support devices or systems without the express written approval of the president of INNO-TECH Co., Ltd. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury of the user. 2. A critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. Rev