Catalogs >
ADI >
LT3964 - Dual 36V Synchronous 1.6A Buck LED Driver with I2C

LT3964 - Dual 36V Synchronous 1.6A Buck LED Driver with I2C
34Pages

Catalog excerpts

LT3964 - Dual 36V Synchronous 1.6A Buck LED Driver with I2C - 1

LT3964 Dual 36V Synchronous 1.6A Buck LED Driver with I2C FEATURES Wide Input Voltage Range: 4V to 36V nn Two Independent 1.6A/40V Synchronous Bucks nn I2C Interface for Internal True Color PWM™ Dimming (8192:1), Analog Dimming and Fault Reporting nn 1000:1 External True Color PWM Dimming and 10:1 External Analog Dimming nn PMOS Switch Driver for PWM and Output Disconnect nn ±3% Constant Current Regulation nn Adjustable Frequency: 200kHz to 2MHz nn Frequency Synchronization with Clock Output nn Programmable OPENLED Protection with Reporting nn Short-Circuit Protection with Reporting nn Programmable Undervoltage Lockout with Hysteresis nn Internal Compensation nn 9 Unique Device Addresses for I2C nn Available in 5mm × 6mm 36-Lead QFN Package The LT®3964 is a dual synchronous step-down DC/DC converter with I2C interface designed to operate as a constant-current and constant-voltage source and is ideal for driving LEDs. The fixed frequency and peak current mode topology result in stable operation over a wide range of supply and output voltages. The ground referred voltage FB pin serves as the input for several LED protection features, and also allows the converter to operate as a constant-voltage source. The maximum output current is set by an external resistor, and the output current amplifier has a rail-to-rail common mode range. LT3964 uses an I2C interface to communicate with a microcontroller to read LED faults, write PWM and analog dimming registers and set fault masking. The I2C PWM input provides LED dimming ratios up to 8192:1. The I2C programmable CTRL register sets the gain of the external CTRL pin, and maximum current sense threshold, providing additional analog dimming capability. APPLICATIONS General Purpose, Industrial, Medical and Automotive Lighting nn Constant-Current, Constant-Voltage Source L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and True Color PWM is a trademark of Analog Devices, Inc. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 7199560, 7321203, 7746300. TYPICAL APPLICATION 50W Dual Buck 1A LED Driver 10µF ×2

Open the catalog to page 1

LT3964 - Dual 36V Synchronous 1.6A Buck LED Driver with I2C - 2

absolute mnximum ratings UHE PACKAGE 36-LEAD (5mm x 6mm) PLASTIC QFN 6ja = 43°C/W, 6JC = 5°C/W EXPOSED PAD (PIN 37) IS PGND, MUST BE SOLDERED TO PCB Consult LTC Marketing for parts specified with wider operating temperature ranges. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/. Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix.

Open the catalog to page 2

LT3964 - Dual 36V Synchronous 1.6A Buck LED Driver with I2C - 5

Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: Do not apply a positive or negative voltage source to PWMTG pin, otherwise permanent damage may occur. Note 3: Do not apply a positive or negative voltage source to INTVCC pin, otherwise permanent damage may occur. Iintto = 5mA is the maximum external load that can be applied. The internal load will be higher due to the power consumption of the IC. Note 4: The...

Open the catalog to page 5

LT3964 - Dual 36V Synchronous 1.6A Buck LED Driver with I2C - 6

EN/UVLO Thresholds vs Temperature EN/UVLO Current vs Temperature VIN Shutdown Current vs Temperature VIN Quiescent Current vs Temperature INTVcc UVLO vs Temperature

Open the catalog to page 6

LT3964 - Dual 36V Synchronous 1.6A Buck LED Driver with I2C - 7

OVFB Threshold vs Temperature OPENLED Threshold vs Temperature SHORTLED Threshold vs Temperature

Open the catalog to page 7

LT3964 - Dual 36V Synchronous 1.6A Buck LED Driver with I2C - 8

Visp-isn Full Scale vs Temperature VISP-ISN 1/2 Scale (vCTRL = 0-7V) v<s Temperature Visp-isn 1/2 Scale (ADIM = 0x7f) vs Temperature VISP-ISN 1/5 Scale (vCTRL = °.4V) vs Temperature Visp-isn 1/10 Scale (Vctrl = 0.3 V) vs Temperature

Open the catalog to page 8

LT3964 - Dual 36V Synchronous 1.6A Buck LED Driver with I2C - 9

LT3964 TYPICAL PERFORMANCE CHARACTERISTICS Minimum Off-Time vs Minimum On-Time vs Temperature 60 FREQ = 1MHz POWER SWITCH ON RESISTANCE (mΩ) TOP SWITCH CURRENT LIMIT (A) PWMTG Falling Edge IL1 200mA/DIV Transient Response at VIN = 34V One LED On to Zero LED On IL1 200mA/DIV Transient Response at VIN = 34V Zero LED On to One LED On PWMTG Rising Edge TOP SWITCH BOTTOM SWITCH Power Switch On-Resistance vs Temperature vs Temperature Top Switch Current Limit vs Duty Cycle Top Switch Current Limit vs Temperature Temperature Minimum OFF Time vs Temperature TA = 25°C, unless otherwise noted....

Open the catalog to page 9

LT3964 - Dual 36V Synchronous 1.6A Buck LED Driver with I2C - 10

LT3964 PIN FUNCTIONS RT (Pin 1): Switching Frequency Adjustment Pin. Set the master clock frequency using a resistor to GND (for resistor values, see Typical Performance curve or Table 3). Do not leave the RT pin open. CTRL1, CTRL2 (Pins 2, 3): Current Sense Threshold Adjustment Pins. The V(ISP-ISN) threshold is regulated by the internal 1.2V reference voltage, CTRL and ADIM[7:0] of the respective channel as follows: V(ISP-ISN) = 0V, when VCTRL < 0.2V V(ISP-ISN) = [(VCTRL –0.2V)/10]•(ADIM[7:0]+1)/256, when 0.2V ≤ VCTRL ≤ 1.1V ALERT (Pin 6): Chip Alert Status Report Pin. An opencollector...

Open the catalog to page 10

LT3964 - Dual 36V Synchronous 1.6A Buck LED Driver with I2C - 11

LT3964 PIN FUNCTIONS SW1, SW2 (Pins 16, 17, 30, 31): SW Pins. The SW pins are the outputs of the internal power switches of each channel. Tie each channel SW pins together and connect them to the appropriate inductor and boost capacitor. These nodes should be kept small on the PCB for good performance. BST1, BST2 (Pins 18, 29): Boost Pins. These pins are used to provide a drive voltage, higher than the input voltage, to the topside power switch of each channel. Place a 0.1µF or larger boost capacitors as close as possible to the IC. ISP1, ISP2 (Pins 19, 28): Connection Points for the...

Open the catalog to page 11

LT3964 - Dual 36V Synchronous 1.6A Buck LED Driver with I2C - 12

UVLO TLIM RAMP GENERATOR SYNCHRONOUS CONTROLLER BOTTOM SWITCH For more information www.linear.com/LT

Open the catalog to page 12

LT3964 - Dual 36V Synchronous 1.6A Buck LED Driver with I2C - 13

LT3964 OPERATION The LT3964 is a dual constant-frequency, current mode step-down DC/DC converter with internal synchronous power switches. The operation of the LT3964 is best understood by referring to the Block Diagram of the IC. In normal operation, with the PWM pin is low or CH1,2_ON signal is low, TGOFFB is disabled. The power switches are turned off, the PWMTG pin is pulled high to ISP to turn off the PMOS disconnect switch, and the ISP and ISN pin bias currents are reduced to several µA. When the PWM pin and CH1,2_ON signal transitions high, the PWMTG pin transitions low after a short...

Open the catalog to page 13