dimming ratio of 5000:1. LED Downlight
30/08/2013 08:49
Figure 2: one from a 45V input to drive the 160 white LED 16-channel LED driver. PWM dimming ratio of 5000:1.
Most battery-powered portable products have one or more display graphical information delivered to the user. However, TFT-LCD screen (even OLED screen) power supply system designers need to be given special attention. TFT-LCD screen in order to achieve the correct power supply, a DC / DC converter will need to be able to properly power-up and power-down sequencing to provide three independent output voltages, namely: AVDD, VON and VOFF. Linear Technology recognizes this and developed specifically for the purpose dedicated monolithic DC / DC converters. The latest of a device is our LT3513. The converter has five independent controlled regulator for providing a TFT-LCD screen inside all the necessary power rails.
Its buck regulator capable of delivering up to 1.2A logic supply rail of continuous output current. You can use LDO controller and an external NPN MOSFET generates a logic low voltage auxiliary power supply. A high power boost converter (ISW = 1.5A), a lower power step-up converter (ISW = 250mA) and a negative output converter (ISW = 250mA) provides three independent output voltage,
that is : LCD screens typically needed AVDD, VON and VOFF. an integrated high-side PNP VON delay of the signal provided on, and the display will be in the protection circuit 4 outputs any one of the below its programmed output voltage up to 10% or more disabling VON, thus helping protect the TFT-LCD screen role. Other features include an integrated Schottky diode for AVDD pin PGOOD pin, output disconnect and for the buck regulator inductor current sensing.
