DC1137A

DC1137A demonstration circuit features the LT3498, 20mA six white LED driver and OLED driver with integrated Schottky. The LT3498 is a dual output boost converter featuring a 2.3MHz PWM LED driver and a PFMOLED driver. The demo board is designed to operate from 3V to 5V, ideal for Li Ion battery powered dual display applications, such as main and sub-displays for cell phones. The LED driver runs at 2.3MHz (typ) fixed frequency, results in tiny circuit size. It can drive 6 white LEDs at 20mA from a minimum of 3V. The demo board offers flexible LED dimming methods. Users can use DC dimming, filter PWM dimming or direct PWM dimming. A MOSFET in series with the LED string disconnects the output capacitor discharge path if PWM terminal becomes low. This results in higher direct PWM dimming ratio. The high side LED current sensing is versatile. The parts functions as a “one wire” current source from the LED string point of view.

• Circuit protection clamps LED driver output to 27V (typ) in open circuit condition
• When CTRL2 is higher than 1.5V, the demo board OLED side output is 16V
• It can deliver up to 24mA from a 3V source
• The OLED driver features a novel PFM control technique
• Novel PFM control technique results in low O/P voltage ripple, high efficiency over wide load range
• Internal PMOS O/P disconnect switch turns itself off in shutdown, disconnecting O/P from I/P source
• Disconnect function is often required in OLED applications
• Switch also minimizes leakage current drain from the battery
• It can deliver up to 24mA output current at OLED driver
• 16.6V max output voltage at OLED driver, 75% typ efficiency at LED driver, VIN=3.6V

Avisos

Do not look at operating LED. This circuit produces light that can damage eyes.