Electronic Components Datasheet Search |
|
APA4801 Datasheet(PDF) 10 Page - Anpec Electronics Coropration |
|
APA4801 Datasheet(HTML) 10 Page - Anpec Electronics Coropration |
10 / 15 page Copyright ANPEC Electronics Corp. Rev. A.5 - Apr., 2001 APA4801 www.anpec.com.tw 10 Input Capacitor, 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 , the external capacitor Ci and the internal re- sistance Ri form a high-pass filter with the corner fre- quency determined in the follow equation : fc (highpass)= 1/ (2 πRiCi) (1) The value of Ci is important to consider as it directly affects the low frequency performance of the circuit . Consider the APA4801 where Ri is 130k Ω internal fixed . Equation is reconfigured as follow : Ci= 1/(2 π*130kΩ*fc) (2) And the ceramic capacitor is recommanded Bias Capacitor, Cb As with any power amplifier , proper supply bypass- ing is critical for low noise performance and high power supply rejection . The capacitor location on both the bypass and power supply pins should be as close to the device as possible . The effect of a larger half supply bias capacitor is improved PSRR due to increased half-supply stability . Typical applications employ a 5V regulator with 10 µF and a 0.1µF bias capacitors which aid in supply filtering . This does not eliminate the need for bypassing the supply nodes of the APA4801 . The selection of bias capacitors , especially Cb , is thus dependent upon desired PSRR requirements , click and pop performance . The ca- pacitor is fed from a 50k Ω source inside the amplifier. To keep the start-up pop as low as possible , the relationship shown in equation should be maintained. 1/(Cb*50k Ω)≤ 1/{Ci*Ri} (3) As an example , consider a circuit where Cb is 4. 7µF , Ci is 1µF and Ri is 130kΩ . Inserting these values into the equation we get 4.26 ≤ 7.69 which satisfies the rule . Bias capacitor , Cb , values of 2.2 µF to 10µF ceramic or tantalum low-ESR capaci- tors are recommended for the best THD and noise performance. Output Coupling Capacitor, Cc In the typical single-supply SE configuration , an out- put coupling capacitor (Cc) is required to block the DC bias at the output of the amplifier thus preventing DC currents in the load . As with the input coupling capacitor , the output coupling capacitor and imped- ance of the load form a high-pass filter governed by equation . fc(highpass)= 1/(2 πR LCc) (4) For example , a 220 µF capacitor with an 32Ω speaker would attenuate low frequencies below 22Hz . The main disadvantage , from a performance standpoint, is the load impedance is typically small , which drives the low-frequency corner higher degrading the bass response . Large values of Cc are required to pass low frequencies into the load . Optimizing Depop Circuitry When the amplifier is in mute mode , both of the out- put stage and input bypass continues to be biased . And no pop noise will be heard during the transition out of mute mode . Power Supply Decoupling , Cs APA4801 is a high-performance CMOS audio ampli- fier that requires adequate power supply decoupling to ensure the output total harmonic distortion (THD) is as low as possible . Power supply decoupling also prevents the oscillations causing by long lead length between the amplifier and the speaker . The optimum decoupling is achieved by using two different type capacitors that target on different type of noise on the power supply leads . For higher frequency tran- sients , spikes , or digital hash on the line , a good low equivalent-series-resistance (ESR) ceramic ca- pacitor , typically 0.1 µF placed as close as possible to the device V DD lead works best . For filtering lower- frequency noise signals , a large aluminum electro- lytic capacitor of 10 µF or greater placed near the audio power amplifier is recommended . Application Note |
Similar Part No. - APA4801 |
|
Similar Description - APA4801 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |