Using PWM 5v to control LEDs at 12v

Thread Starter

FroceMaster

Joined Jan 28, 2012
662
Can this curcuit work to "Dimmer" of the LED's ?
using TPIC6B595 to control the LEDS, all is then controlled from the Microchip PIC16Fxxxx
Led are 1,85v an resistor R3-R6 is 68Ohm
Using 13.2mA pr Line Giving med total Watt of 156mW pr line,


PWM Out.pngDatasheet for TPIC6B595
Shifting time will be 3 sec interval, but for Dimming lights i will run a 5khz PWM DC 5-95 % i think.
TPIC6B595 datasheet.JPG
 

schmitt trigger

Joined Jul 12, 2010
463
Looks good.
The turn-off time is related directly to the gate resistor value.
You may want to check this to ensure it is switching quickly enough.
Most likely it is, but is something you should check.
 

Thread Starter

FroceMaster

Joined Jan 28, 2012
662
Looks good.
The turn-off time is related directly to the gate resistor value.
You may want to check this to ensure it is switching quickly enough.
Most likely it is, but is something you should check.
This is the way we dim LED's and control motor speed with a PIC. Just replace the motor with 12V strings of Led's.
View attachment 232896
Not so smart, i need digital control, not with a variabel resistor.
 

djsfantasi

Joined Apr 11, 2010
7,830
Not so smart, i need digital control, not with a variabel resistor.
You don’t need the variable resistor. The PIC can provide the digital control.

If you don’t need the pic, all you need is the IRLZ44N and the 47k resistor.

BTW, if you’re controlling leds, you don’t need the diode across the motor.
 

Thread Starter

FroceMaster

Joined Jan 28, 2012
662
I will have to use the mcu,
Simpel control like i have in my first post. Have to check the resistor, think the pwm will be 5khz, but dont know yet.
 

Audioguru again

Joined Oct 21, 2019
3,523
Nobody makes an LED rated at one voltage. An LED has a range of voltages. Yours is probably red with a voltage range from 1.7V to 2.2V.
If all 6 LEDs are 1.7V then the 68 ohms fed from 12.0V produces a current of 26mA which might destroy the LEDs.
If the LEDs are 2.2V then six of them need 13.2V plus some voltage for the resistor then they will not produce any light.
 

Thread Starter

FroceMaster

Joined Jan 28, 2012
662
Nobody makes an LED rated at one voltage. An LED has a range of voltages. Yours is probably red with a voltage range from 1.7V to 2.2V.
If all 6 LEDs are 1.7V then the 68 ohms fed from 12.0V produces a current of 26mA which might destroy the LEDs.
If the LEDs are 2.2V then six of them need 13.2V plus some voltage for the resistor then they will not produce any light.
Ok, then nevermind the datasheet ?
If datasheet says 1,85 i will asume 1.8 to 1.9, or else why have datasheet

The TC4420, just connect direct to MCU pinout. ?
INPUT =5V ?
VDD = 12V ?
GND is ground
OUTPUT Is to the LEDs
No resistor between mcu and Device ?
 

Audioguru again

Joined Oct 21, 2019
3,523
The motor speed controller circuit operates at a low frequency that might cause visible flicker on LEDs.
Reduce the 0.1uF capacitor value for a higher frequency with less flicker.
 

ElectricSpidey

Joined Dec 2, 2017
1,806
No, he wont be using this circuit to drive the LEDs, it was only an example that the driver can do more than just drive a MOSFET.

Driving LEDs would come directly from the MCU.
 

Thread Starter

FroceMaster

Joined Jan 28, 2012
662
No, he wont be using this circuit to drive the LEDs, it was only an example that the driver can do more than just drive a MOSFET.

Driving LEDs would come directly from the MCU.
What do u mean. I drive up to 170 Leds with the TPIC6B595 that is controlled by MCU, the MCU should also handle the contrast of the LEDs. By a 5v PWM Signal
 
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