An 250mA general cellular phone LED driver can drive 9 LED

Linear Technology Corporation (Linear Technology Corporation) launched inductorless, low noise, high efficiency LED driver LTC3219, the device for cellular phone display and lighting. LTC3219 based, vice and RGB display provides 9 separate configurable current sources. The display current is set by an accurate internal current reference. The general current source can be controlled in a digital way, and has the independent dimming, brightness, flicker and gray level control, and can be programmed by a simple two wire I2C serial interface. The 2.9V to 5.5V input voltage range of the LTC3219 has been optimized for single-cell Li ion / polymer battery applications. When the lithium ion battery (3.6V nominal value) is driven, the efficiency is 91%, the quiescent current is only 400uA, and the working time of the battery is prolonged. The rate dependent switch reduces the conduction and radiation noise (EMI).

The LTC3219 multi mode charge pump operates at low noise constant frequency and automatically optimizes the voltage on the LED current source. The device is powered up in the 1x mode and automatically switches to the boost mode (1.5x) when the LED current source in any start-up is in a fast differential voltage, and the subsequent voltage drop switches the device to a voltage doubler mode (2x). Internal circuitry prevents inrush current and excessive input noise during start-up and mode switching. In addition, the device also has a short circuit and overheating protection.

LTC3219 uses a flat (0.75mm) 20 lead QFN (3mm x 3mm) package, available from stock. The integrated circuit requires only 5 capacitors, LED power supply, can form a complete and delicate current controller solution. In 1000 pieces for the bulk purchase, each price starts at $1.80.

Performance overview: LTC3219

Multi mode (1x/1.5x/2x), low noise charge pump achieves up to 91% efficiency

Transfer rate limited switches reduce conduction and radiated noise (EMI)

Total output current up to 250mA

9 independently configurable 28mA current sources with 64 linear brightness control stages

Using the two wire I2C interface for each current source for independent on / off, brightness level, flicker and gray control

2.9V to 5.5V input voltage range for lithium-ion / polymer battery applications optimized

Internal current reference

Configurable ENU pin for asynchronous LED on / off control

Automatic or manual mode switching

Internal soft start limits inrush current

Short circuit / overheat protection

Slim, flat 3mm x 3mm x 0.75mm QFN-20 package

Source: International Electronic Business