The super capacitor fills the power gap between the battery and the general capacitor. It can supply higher trigger power than the battery and store more energy than the general capacitor. Super capacitor module It can be considered that peak power events (such as GSM/GPRS RF burst transmission, GPS data reading, music broadcasting, flash photography and video broadcasting) supply the required trigger power, and then accept the recharging of the battery. Farad capacitor Its advantages include extended talk time, extended battery life, brighter flash and better music quality. Designers can also use this to save space and cost, because they only need to consider the battery and power circuit that meet the uniform power consumption, and do not need to pay attention to the peak load.
At present, mobile phones generally use Class D audio amplifiers. These amplifiers use two pairs of FETs in an H-bridge circuit to control the speaker coil.
The coil is driven in the opposite direction. The power supply of this circuit is generally 3.6V battery. Mobile phones with stereo audio have a pair of amplifiers and speakers. For 8 Ω speakers, audio power=3.6V2/8 Ω=1.6W, or 3.2W for stereo speakers. Battery current under peak stereo audio power=3.2W/3.6V=0.9A. Therefore, audio broadcasting in this case may be affected by power constraints, distortion and interference.
Problem 1: When the peak battery current exceeds 1A, audio noise/buzzing will occur, which will cause significant ripple on the power supply voltage of the audio amplifier.
Super capacitor manufacturer If the total impedance of the battery pack+connector+PCB wiring is equal to 150m Ω, the peak current of 1A will ripple 150mV on the power supply voltage, and the peak current of 1.8A will ripple 270mV. This ripple in the power supply voltage will bring audio noise to the listener. The peak current of GSM/GPRS/EDGE transmission is as high as 1.8A, so audio noise will also occur, and the user will hear 217Hz buzz during the call.
Problem 2: The battery cannot meet the peak power requirements of wireless data transmission and audio amplifier at the same time, which will lead to distortion.
When users use GSM/GPRS/EDGE mobile phones to appreciate music, the mobile phone battery will not be able to simultaneously supply peak audio current and peak RF transmission power to respond to network visits. The network will periodically visit the mobile phone to track which cell the mobile phone is located in, and confirm the transmission power that the mobile phone should use. During this network visit, the power supply of the audio amplifier may drop when the mobile phone responds, and the user will hear a "click". However, the battery can easily supply a uniform audio current of about 100mA to 200mA.
Question 3: Limited audio power and poor low voice echo in CDMA, GSM&3G mobile phones.
No matter what type of mobile phone, its audio ability and quality depend on the output power of the audio amplifier and the impedance of the speaker. In a typical mobile phone equipment, two Class D amplifiers drive a pair of 8 Ω speakers under the 3.6V power supply supplied by the battery. As mentioned above, the high audio power is 3.2W and the peak battery current is 0.9A. As a result, whether through the internal speaker of the mobile phone or through the external connected speaker/headset, the audio function will be shallow and low-power, and the function of low-voice echo is very limited.
The other circuit scheme uses Farad capacitor, which can handle all the above problems and supply four times of peak audio power. CAP-XX HS206 is a 0.55F, 85m Ω dual cell supercapacitor, which is used to supply peak power while the battery supplies uniform power. The boost converter charges the super capacitor to 5V.
In addition, the ripple on the battery voltage due to RF emission will not be reflected on the audio amplifier. These ripples have been filtered out by the line regulator circuit and super capacitor of the boost converter, thus eliminating the 217Hz hum completely.
