Hi, i'm trying to build a 14 segment number display using these 10W high powered LED bars. Every LED is controlled by a IRF530N and de final MOSFET at the bottom is an IRLZ44N used to dim the whole thing using one PWM pin on the arduino mega controlling it. Every LED bar has current limiting built-in but in the schematic it is displayed as 13.3Ohm resistors. This circuit works fine until we start turning off LED's, whenever there are 4 or less LED's active the PWM seems to stop working causing the LED's to ramp up to full brightness. In this configuration the LED's consume 480-600 mA on full power depending on the amount of enabled LED's (less LED's = Higher Amperage).
i hope you can help me with a few questions:
Q1: What would be the proper way to wire up 2 MOSFETS in series while being able to control them indepentently? this is the only way i found to get them to work but it feels like there is a much better way to do this.
Q2: Would it be better to use a logic level MOSFET as PWM switch? we're planning to have a PWM frequency of 1-2KHz
Q3: Why does the LED's power consumption decrease when more LED's are enabled? the supply is not limited.
Also, i know it would be better to control every led using PWM individually but we dont have enough PWM outputs available.
i hope you can help me with a few questions:
Q1: What would be the proper way to wire up 2 MOSFETS in series while being able to control them indepentently? this is the only way i found to get them to work but it feels like there is a much better way to do this.
Q2: Would it be better to use a logic level MOSFET as PWM switch? we're planning to have a PWM frequency of 1-2KHz
Q3: Why does the LED's power consumption decrease when more LED's are enabled? the supply is not limited.
Also, i know it would be better to control every led using PWM individually but we dont have enough PWM outputs available.