A brief introduction to the application knowledge of tantalum capacitors in power supplies
Published on:2021-05-27
Generally, when tantalum capacitors are used, if there is no large ripple, the withstand voltage can be as long as 20% greater than the actual value. That is, 10V for 7805 output is enough, and 6V is enough; 16V for 7809 is enough, but 10V is not enough. There will be big problems. The output of the three-terminal regulator does not need to be connected to a large capacitor. Depending on the actual load, generally 100mA is connected to 47-100uF, 1A is connected to 470-1000uF, and it is best to connect another 0.01-0.1 uF small ceramic chip or monolithic capacitor.
Tantalum capacitors are widely used in audio components, filtering, anti-crosslinking, high-frequency compensation, DC feedback... can be seen everywhere. But if it is broken down by function, manufacturing materials, and manufacturing methods, it cannot be explained overnight. So to narrow the scope, this article only talks about electrolytic capacitors, and only talks about aluminum electrolytic capacitors for power smoothing and filtering. Every audio machine needs power supply-except for the passive front stage, since power is needed, the action of "filtering" is indispensable. Don't fight with me, tantalum capacitors use battery power supply, of course, it is not necessary to smooth the power supply. But the battery charging circuit also has rectification and filtering, so the filter capacitor will still exist. The official name of the filter capacitor we are used to now should be: aluminum foil dry electrolytic capacitor. From my observation, except for the Canadian Sonic Frontiers vacuum tube front stage, which used PP plastic capacitors for filtering in the high-voltage voltage regulator circuit, all other models use aluminum foil dry electrolytic capacitors; therefore, it is necessary for netizens to learn more about it. Faced with the tantalum capacitors that serve as power smoothing and filtering in the power supply voltage regulator circuit, what will you first think of? ─Capacity? Withstand voltage? There must be a capacity mark on the outer skin of the capacitor, which refers to the electrostatic capacity; there must also be a withstand voltage mark, which refers to the working voltage or the rated voltage. The working voltage (working voltage) is referred to as WV, which is an absolute safe value; if it is surge voltage (referred to as SV or Vs), it is the surge voltage or breakdown voltage; if this voltage value is exceeded, the capacitor will be guaranteed to be drowned by the wave-be careful of the capacitor. burst!