IC Integrated Circuit of Multi-LED Camera Light Charge Pump

Product Description

600mA Low Noise Multi-LED Camera Light Charge Pump
 
Features
Charge Pump Provides High Efficiency with
Automatic Mode Switching
Multimode Operation: 1x, 1.5x, 2x
Four Low Dropout LED Outputs
Up to 600mA Total Output Current
Independent Torch and Flash ISET and Enable Pins
Low Noise Constant Frequency Operation*
PWM Brightness Control via the EN2 Pin
Low Shutdown Current: 4µA
Internal Soft-Start Limits Inrush Current During
Start-Up and Mode Switching
Open/Short LED Protection
No Inductors
(3mm x 3mm) 16-Lead QFN Plastic Package
 
Applications
Multi-LED Camera Light Supply for Cellphones/
DSCs/PDAs
 
Description
The LTC®3217 is a low noise charge pump DC/DC converter
designed to power four high current LEDs. The
LTC3217 requires only four small ceramic capacitors and
two current set resistors to form a complete LED power
supply and current controller.
 
Built-in soft-start circuitry prevents excessive inrush current
during start-up and mode changes. High switching
frequency enables the use of small external capacitors.
Independent high and low current settings are programmed
by two external resistors. Shutdown mode and current
output levels are selected via two logic inputs.
 
The current through the LEDs is programmed via ISET1 and
ISET2. In addition, the brightness can be controlled by
pulse width modulation of the EN2 pin.
 
The charge pump optimizes efficiency based on the voltage
across the LED current sources. The part powers up
in 1x mode and will automatically switch to boost mode
whenever any enabled LED current source begins to enter
dropout. The first dropout switches the part into 1.5x
mode and a subsequent dropout switches the part into 2x
mode. The LTC3217 resets to 1x mode whenever the part
is shut down.
The LTC3217 is available in a low profile 16-lead (3mm ×
3mm × 0.75mm) QFN package.