Linear Technology Introduces Inductorless LED/CAM Driver LTC3207

Photocoupler

Linear Technology Corporation (Linear Technology Corporation) Release inductorless, low noise, high efficiency LED / CAM driver The LTC3207, the device for cell phone displays and lighting. The LTC3207 provides 12 independently configurable current sources for primary, secondary, RGB, auxiliary or general purpose (GPO) displays/lights/outputs, and the IC also has the ability to drive a 400mA high current LED camera light. The universal current source features a digital controller with independent dimming, brightness, flash, and grayscale control that can be set up via a simple two-wire I2C serial interface. The current level of the camera flash (pulse) or flashlight (continuous) can be selected in real time via the CAM HL pin and can also be controlled via the I2C port. The LTC3207 's 2.9V to 5.5V input voltage range has been optimized for single cell Li-Ion/Polymer battery applications. When driven with a lithium-ion battery (nominally 3.6V), the efficiency is 92% and the quiescent current is only 500uA, maximizing battery run time. Switching operation with limited slew rate reduces conducted and radiated noise (EMI).

The LTC3207's multimode charge pump operates with low noise and constant frequency, automatically optimizing efficiency based on VIN and LED forward voltage conditions. The device powers up in 1x mode and automatically switches to boost (1.5x) mode when any enabled LED current source begins to enter a voltage drop state, and the subsequent voltage drop switches the device to a voltage doubler ( 2x) mode. Internal circuitry prevents inrush current and excessive input noise during startup and mode switching. In addition, the device features short-circuit protection and thermal protection.

The LTC3207 is available from stock in a flat 24-lead QFN (4mm x 4mm) package. The IC requires only five small capacitors to form a tiny, complete LED power and current controller solution. Buy in 1,000-piece quantities starting at $1.95 each.

Performance Summary: LTC3207

• Multi-mode 1x/1.5x/2x charge pump delivers up to 92% efficiency • Switching rate limited switching operation reduces conducted and radiated noise (EMI)
• Total output current up to 600mA
• 12 independently configurable 28mA current sources with 64 linear brightness control stages • 400mA CAM LED current source with 16 levels of linear brightness control and a two second high current safety timer • Two currents with a two-wire I2C interface Source for independent on/off, brightness, flicker and grayscale control • Automatic or manual mode switching • Low noise, constant frequency operation • Internal soft start limiting inrush current • Short circuit protection / thermal protection • 2.9V to 5.5V Input voltage range • Flat 4mm x 4mm x 0.75mm QFN-24 package