Energy efficient LED driver circuit should be used in Automotive applications for the betterment of battery, here the Automotive LED driver circuit composed with Low Noise, Regulated Charge Pump DC/DC Converter IC LTC3200 from linear technology.
This IC will give upto 100mA output current with low noise constant frequency operation, it takes input voltage between 2.7V to 4.5V and the circuit with this IC may not require inductor element. It can be used in White LED Backlighting and automobile applications.
Circuit Construction & Working
The LTC 3200 is constant frequency switched capacitor voltage doublers and it produce a regulated output voltage from a 2.7V to 4.5V input with up to 100mA of output current. It requires only few external operating components and hence reduce the BOM. This IC and Circuit designed to work with low voltage and current. If you want to use this circuit in automotive applications then bring the battery voltage and current to 4V by using voltage regulators. Otherwise you can use external battery.
The LTC3200 comes in MS8 package and also the LTC3200-5 is available in a 6-pin ThinSOT package.
Here upto 6 White LEDs are connected to the Vout and Pgnd pins, feedback signal is given from LED1 this act as output divider to the feedback pin and it required to LTC3200 for program the output voltage. C+ and C- pins are fed with Flying Capacitor. pin 6 is Active Low Shutdown Input pin, Circuit operation disabled if low signal appears to it. Make the high or 3V input to this pin for Enabling the circuit operation. You can apply PWM signal to this pin to control the brightness of LEDs.
Pins 4 & 5 tied to ground supply, this circuit can be used as headlight or tail light or the brightness controlled lighting applications in automobiles.