description:
The output voltage of the "POUT" terminal of the MAX1703 switching power supply is set to 3.4V, and the linear regulator consisting of the P-channel FET Q1 and the on-chip standby amplifier has an output voltage of 3.3V. Therefore, when the USB peripheral is powered by the battery pack, Q1 The power loss is almost negligible. When the external device is connected to the USB port, the diode D1 is forward biased to make the switching power supply "idle" state; that is, as long as the source voltage of Q1 is higher than 3.4V, the external device is always powered by the USB port. At the same time, the USB port also charges the battery pack through a constant current source composed of a PNP transistor Q2, etc., and the resistance value of the resistor R1 can be set to set the charging current to meet the requirements of the ten-hour charging system. Once the external device is disconnected from the USB port, the switching power supply immediately exits the "idle" state and continues to be powered by the internal battery pack.
Small UPS power circuit:
The role of the car amplifier is to select and preprocess the audio input signal, and to amplify the power, so that the electrical signal has the ability to drive the speaker. Car power amplifiers are slightly different from those in ordinary home theaters. Because many car hosts integrate power amplification functions to play a pre-amplification function, car power amplifiers are sometimes called post-amplification, which means that they can be connected and amplified. High level input over.
Amplifier is an indispensable component of a good sound system. The power amplifier on the host often cannot really amplify the sound current, so if you want to have a good music experience, you must install a power amplifier. Generally speaking, the power of the power amplifier is greater than the power of the speaker. Many car owners think that installing a bass amplifier is just to have a shocking effect. In fact, this is ignoring the characteristics of the car. No matter how high-end cars are, there will be noise. The bass part of the music released during driving will be different to different degrees. The roar is mixed, and the addition of a bass amplifier can increase the reserve power, reduce noise interference and reduce distortion.
When the power tube of the power amplifier is working, the temperature of the tube core is about 120 degrees, and the heat must be dissipated in a certain way. But the temperature of the Heat Sink exceeds 60 degrees, and even the case is hot, which may be a problem. Therefore, it can be seen that adding a cooling fan with good cooling performance and high reliability is a necessary way and the key to solving the heat dissipation problem of the power amplifier system.
Original Electronics Technology (Suzhou) Co., Ltd. , https://www.original-te.com