LM3646 Texas instruments

LM3646

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LM3646

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Описание

The LM3646 utilizes a 4-MHz fixed-frequency synchronous boost converter to provide power to dual 1.5-A constant current LED sources. The high-side current sources allow for grounded cathode LED operation providing flash current up to 1.5 A total. An adaptive headroom regulation scheme ensures the LED currents remain in regulation and maximizes efficiency. The combination of dual LED driving capability, high LED current, small solution size and high level of adjustability make the LM3646 perfect for camera phone LED flash and torch applications. The LM3646 is controlled through an I2C-compatible interface. The main features of the LM3646 include: a hardware flash enable (STROBE) input for direct triggering of the flash pulse, a hardware Torch enable (TORCH) for movie mode or flashlight functions, a TX input which forces the flash pulse into a low-current torch mode allowing for synchronization to RF power amplifier events or other high-current conditions, an integrated comparator designed to monitor an NTC thermistor and provide an interrupt to the LED current, and a programmable input voltage monitor which monitors the battery voltage and can reduce the flash current during low battery conditions. A hardware enable (ENABLE) input provides a hardware shutdown during system software failures. The 4-MHz switching frequency, overvoltage protection, and adjustable current limit allow for the use of tiny, low-profile inductors and (10-µF) ceramic capacitors. The device is available in a small 20-bump DSBGA package and operates over the –40°C to 85°C temperature range.

High-Side Current Sources Allowing for Grounded
LED Cathode for Improved Thermal Management
> 85% Efficiency in Torch and Flash Modes
Small Solution Size < 20 mm²
Accurate and Programmable Flash LED Current from
24 mA to 1.5 A in 11.7-mA Steps
Accurate and Programmable Torch LED Current
from 2.5 mA to 187 mA in 1.5-mA Steps
Dual 1.5-A High-Side Current Sources for Dual
LED Drive
Hardware Flash and Torch Enables
Hardware Enable Pin
Soft-Start Operation for Battery Protection
LED Thermal Sensing and Current Scale-Back
Synchronization Input for RF Power Amplifier
Pulse Events
VIN Flash Monitor Optimization
1-MHz I²C-Compatible Interface
I²C-Programmable NTC Trip Point
0.4-mm Pitch, 20-Bump DSBGA

Input voltage type	DC/DC
Topology	Boost, current mode
Vin (min) (V)	2.7
Vin (max) (V)	5.5
Vout (max) (V)	5.5
Vout (min) (V)	2.7
Iout (max) (A)	1.5
Iq (typ) (mA)	1
Features	I2C control, Input/Output Isolation, LED Thermal Monitor, Load Disconnect During Shutdown, OVP, Over Current Protection, Synchronous Rectification
Operating temperature range (°C)	-40 to 85
Dimming method	Analog, PWM
Number of channels	2
Rating	Catalog