DC1055A: 28mA x9, 2.9 ~ 5.5V in, Charge Pump

Summary

Demonstration circuit 1055 is a 250mA Universal Nine Channel LED Driver with two RGB displays and three white LEDs featuring the LTC3219.

The LTC3219 is a low noise charge pump designed to drive nine universal LED current sources. The LTC3219 requires only five small ceramic capacitors to form a complete LED power supply and current controller.

The maximum display currents are set with an internal precision current reference. On/Off blinking, gradation, and intensity are achieved via an I2C serial interface. See the LTC3219 data sheet for more information on this process. There are 64 dimming states available for the universal LEDs.

The charge pump optimizes efficiency based on the volt-age 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 drop out. The first dropout switches the part to 1.5x mode and a subsequent dropout switches the part into 2x mode. The part resets to 1x mode whenever a data byte is up-dated via the I2C port.

Specifications

Manufacturer	Analog Devices Inc.
Category	Lighting
Sub-Category	LED Drivers - DC In
Eval Board Part Number	DC1055A-ND
Eval Board Supplier	Analog Devices Inc.
Eval Board	Normally In Stock
Voltage In	2.9 ~ 5.5 V
Topology	Step Up Switch Cap, Charge Pump
Current Out	250 mA
Voltage Out (Max)	4 V
Outputs and Type	9 Non-isolated
Efficiency @ Conditions	>60%, 3.3 ~ 5.25V in, 3.2V @ 15 mA/LED (x9)
Features	Current Limit (Adj. or Fixed) I²C Interface Short Circuit Protection Soft Start Thermal Protection
Switching Frequency	850 kHz
Component Count + Extras	11 + 4
Design Author	Linear Technology
Application / Target Market	LCD Backlighting
Main I.C. Base Part	LTC3219
Date Created By Author	2005-11
Date Added To Library	2015-06