Capacitive Power Supply Microchip

In a resistor based design if there is any load current then the voltage drop across z 1 will increase and vout will correspondingly decrease which is undesirable.

Capacitive power supply microchip.

Power supply is more efficient than a resistive transformerless power supply discussed next. 2004 microchip technology inc. Pic18 q41 the pic18 q41 family of mcus combines sophisticated analog peripherals and powerful cips for small high performance data acquisition and sensor interfacing applications to help reduce development time. A capacitive power supply also called a capacitive dropper is a type of power supply that uses the capacitive reactance of a capacitor to reduce the mains voltage to a lower voltage.

First the high withstanding voltage required of the capacitor along with the high capacitance required for a given output current mean that this type of supply is only practical for low power applications. 2016 microchip technology inc. Disadvantages of capacitive power supply. There are two important limitations.

Power supply i m working in a project with very tight space limitations i need 3 3v 400ma from 120ac mains i have explored some possible solutions but space is always the constraint isolated or non isolated will work. To conserve power the device mostly operates in an ultra low power sleep mode in which minimal current µa is drawn. The pic24f gu gl family of xlp mcus is packed with many cips that function in power saving modes offering ultra low power operation for battery powered designs. Good power supplies support a range of output current from vout while holding the output voltage constant.

The second is that due to the absence of electrical isolation between. Qt ics are optimized for low power operation. The voltage at the load will remain constant so long as current out iout is less than or equal to current in iin. So we can use the capacitive supply circuit that microchip gives in its app note as an example of what a capacitive supply for an illumination grade led might look like.

Resistive power supply the board includes both a resistive and capacitive power supply. But the application microchip seemed to have in mind in its note was powering low power microcontroller chips not leds. Here are the issues i ve had with the alternatives. Higher cost than a resistive power.

Poor power supply design. Periodically the qt ic wakes up to perform sampling and communication routines that consume ma of current. Not isolated from the ac line voltage which introduces safety issues. This section will discuss part selection with their associated power ratings.

More cost effective than a transformer based or switcher based power supply.