Here is a web-based tool that will give you the schematic and will calculate the component values, automatically:Ĥ) Vripple = the peak-to-peak output voltage ripple that you can tolerateĥ) Fmin = the desired switching frequency (up to 100 kHz). It is usually done with a "switch-mode power supply" (smps) circuit.Įdit: OK, you can raise 5 Volts to 9 Volts very, very easily, using the MC34063A chip, if you don't need more than about 300 mA of current. (You will probably also need to have a resistor in between the charger and the battery, to limit the current to a level that is safe for the battery.)įor methods and circuits to raise the supply voltage, from 5 Volts to about 9 Volts, do a search for "boost converter" or "boost mode" smps. To be able to do that, you would need a circuit to raise the supply voltage to at least as high as the desired battery voltage. In this case, you are wanting to charge a higher-voltage battery from a lower-voltage supply. There are also dedicated battery-charging circuits, with features such as automatically stopping charging when the battery is fully charged, and contouring the voltage and current levels during charging. You will need to know what voltage the battery should be charged from (it is always a little higher than the desired final battery voltage), and what the ideal charging current might be. Usually, you would also need to limit the current flowing into the battery, during charging, so the battery wouldn't get too hot, so it wouldn't be damaged or explode. In order to charge a battery, the charging voltage must be at least as high as the desired battery voltage, and not too much higher. Re: How to charge a 9 volt from a 5 volt supply
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