An introduction of inductorless high current white LED driver LTC3218

Linear Technology Corporation (Linear Technology Corporation) has no inductor type high current white LED driver LTC3218, the device provides LED current up to 400mA. The multi-mode architecture switches between 1x or 2x boost mode, which monitors the voltage at both ends of the LED current source, switching mode only when the ILED voltage drop is detected. LTC3218 adjust the LED current by using the high voltage side detection resistor. This achieves low pressure drop and allow the device to stay in 1x mode for longer periods of time, thus the lithium ion / polymer battery voltage range to maximize efficiency, and thus prolong working time and minimizes noise.

LTC3218 provides a pulse current of up to 400mA for the camera flash, or provides a continuous current of up to 150mA for the camera flashlight lighting applications, with the ability to facilitate single resistor programming. When the input voltage of the integrated circuit is close to the forward voltage of LED, an ultra low dropout current source begins to provide accurate current to the LED. The LTC3218 uses a built-in soft start circuit to prevent excessive inrush current during start-up and provides a two second flash current timeout for LED protection. The device inductorless charge pump structure, 1MHz high switching frequency and small number of external components (a jumper capacitor, a programming resistor, two bypass capacitors) and compact DFN package can ensure the solution composition and economic area is very fragile, so it is very suitable for the camera the phone in the video and flash applications, digital cameras and other portable lighting applications. LTC3218 requires only one lead to the LED, which is useful in flip phone, because in this type of mobile phone, drive IC and LED are located on both sides of the hinge.

LTC3218 uses a flat (0.75mm) 2mm 3mm 10 lead DFN package, available from stock, rated operating temperature range of -40 x to +85 C. In 1000 pieces for the bulk purchase, each price starts at $1.44.

Performance summary:

Multi mode work: 1x or 2x boost mode

Automatic mode switching

Output current

- pulse: 400mA

- continuous: 150mA

Low noise constant frequency operation

* two second flash current timeout to protect LED

Automatic soft start

Output disconnect

No inductors

220m internal high side current sense resistor

* single resistance programming capability for pulse / continuous mode

The application circuit (all components and delicate height