First of all let’s be familiar with a 12V LED PWM controller dimmer circuit, soon after at the concluding part of the article we’ll observe how the similar could be applied applying 5V supply in addition to a mosfet.
The following circuit thought displays an easy PWM controller circuit making use of IC 555 that are available for handling LED intensities from 0 to maximum digitally.
In the image above, the supply is gained from an SMPS unit which used on the PWM circuit by means of a LM338 current controller circuit stage.
The pot P1 is commonly used for adjusting the PWM duty cycles to the LED bank for accomplishing the required power levels.
The resistor R3 decides the reducing current level from the IC LM338, perhaps it is measured with the following procedure:
R3 = 1.25/LED current
The circuit displays a 36 LED (1 watt each) bank being determined by the PWM as well as the current controller stages.
The LED series resistors are released for protecting each 3 LED string from over voltage. seeing that the overall advanced voltage drop of the strings form to 3.3 x 3 = 9.9V and the supply voltage 12V that may be about 2V higher.
R3 handles the overall current for the overall LED bank, and could be measured by applying the previously discussed formula, for the proven design the consequence could be estimated as:
R3 = 1.25/0.35 x 12 = 0.29 Ohms
Wattage = 1.25 x 0.35 x 12 = 5.25 watts, the following 0.35 is the current by way of each LED string, 12 is the range of strings, and 1.25 is the fixed reference as described by the IC LM338 datasheet.
In instances where the supply voltage is confined to 5V, as well as the planned programs demands a PWM control of the LEDs as a result of a mosfet, the following circuit could be aptly designed for the same.
While you can easliy observe, the above configuration is similar to the first one, barring the addition of the voltage booster level between pin3 of the IC 555 as well as the mosfet gate.
Listed here several diodes and capacitors appropriately boost the pin3 PWM level from 5V peak to 10V peak, this evolves into essential since a mosfet is getting employed for the regulations, and mosfets usually do not reply optimally with gate voltages cheaper than 9V.
The proven mosfet gate voltage booster stage could be as well practiced with PWM outputs which may be produced from an Arduino board or other MCUs.