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LM3434

BST

CSP

CSN

BST2

DMO

DIMR

COMP

ADJ

DIM

CGND

0.47 PF

2.2 PF

0.01

-12V

GND

4.7 PF

+3.3V

DIM

44.2k

0.1

ADJ

-12V

270 pF

22 PF

6 PH

0.01 LED CATHODE

LED ANODE

LED

LM3434

www.ti.com

SNVS619B –MARCH 2010–REVISED MAY 2013

Common Anode Capable High Brightness LED Driver with High Frequency Dimming

Check for Samples: LM3434

FEATURES

DESCRIPTION

The LM3434 is an adaptive constant on-time DC/DC

• Operating Input Voltage Range of –9V to -30V

buck (step-down) constant current controller (a true

w.r.t. LED Anode

current source). The LM3434 provides a constant

• Control Inputs are Referenced to the LED

current for illuminating high power LEDs. The output

Anode

configuration allows the anodes of multiple LEDs to

be tied directly to the ground referenced chassis for

• Output Current Greater than 6A

maximum heat sink efficacy. The high frequency

• Greater than 30kHz PWM Frequency Capable

capable architecture allows the use of small external

• Negative Output Voltage Capability Allows

passive components and no output capacitor while

LED Anode to be Tied Directly to Chassis for

maintaining low LED ripple current. Two control

Maximum Heat Sink Efficiency

inputs are used to modulate LED brightness. An

analog current control input is provided so the

• No Output Capacitor Required

LM3434 can be adjusted to compensate for LED

• Up to 1MHz Switching Frequency

manufacturing variations and/or color temperature

• Low I

, 1mA Typical

correction. The other input is a logic level PWM

control of LED current. The PWM functions by

• Soft Start

shorting out the LED with a parallel switch allowing

• Adaptive Programmable ON Time Allows for

high PWM dimming frequencies. High frequency

Constant Ripple Current

PWM dimming allows digital color temperature

• 24-Pin WQFN Package

control, interference blanking, field sequential

illumination, and brightness control. Additional

APPLICATIONS

features include thermal shutdown, V

under-voltage

lockout, and logic level shutdown mode. The LM3434

• Projection Systems

is available in a low profile 24-pin WQFN package.

• Solid State Lighting

• Automotive Lighting

TYPICAL APPLICATION CIRCUIT

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

2All trademarks are the property of their respective owners.

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.

Summary of content (20 pages)

PAGE 1
LM3434 www.ti.com SNVS619B – MARCH 2010 – REVISED MAY 2013 Common Anode Capable High Brightness LED Driver with High Frequency Dimming Check for Samples: LM3434 FEATURES DESCRIPTION • The LM3434 is an adaptive constant on-time DC/DC buck (step-down) constant current controller (a true current source). The LM3434 provides a constant current for illuminating high power LEDs.
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LM3434 SNVS619B – MARCH 2010 – REVISED MAY 2013 www.ti.com NC BST2 DIMO DIMR 21 20 19 CSN 23 22 CSP 24 CONNECTION DIAGRAM TON 1 18 HS ADJ 2 17 HO EN 3 16 BST DIM 4 15 VCC VIN 5 14 LO CGND 6 13 LS 9 10 11 NC SS NC 12 8 NC 7 VEE COMP LM3434 Figure 1. 24-Lead WQFN (Top View) See RTW0024A Package PIN DESCRIPTIONS 2 Pin Name Function 1 TON On-time programming pin. Tie an external resistor (RON) from TON to CSN, and a capacitor (CON) from TON to VEE.
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LM3434 www.ti.com SNVS619B – MARCH 2010 – REVISED MAY 2013 PIN DESCRIPTIONS (continued) Pin Name 23 CSN Current sense amplifier inverting input. Connect to current sense resistor negative terminal. Function 24 CSP Current sense amplifier non-inverting input. Connect to current sense resistor positive terminal. EP VEE Exposed Pad on the underside of the device. Connect this pad to a PC board plane connected to VEE.
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LM3434 SNVS619B – MARCH 2010 – REVISED MAY 2013 www.ti.com These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. ABSOLUTE MAXIMUM RATINGS (1) If Military/Aerospace specified devices are required, contact the Texas Instruments Semiconductor Sales Office/ Distributors for availability and specifications. VALUE / UNIT VIN, EN, DIM, ADJ to CGND -0.
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LM3434 www.ti.com SNVS619B – MARCH 2010 – REVISED MAY 2013 ELECTRICAL CHARACTERISTICS Specifications in standard type face are for TJ = 25°C and those with boldface type apply over the full Operating Temperature Range ( TJ = −40°C to +125°C). Minimum and Maximum limits are specified through test, design, or statistical correlation. Typical values represent the most likely parametric norm at TJ = +25ºC, and are provided for reference purposes only.
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LM3434 SNVS619B – MARCH 2010 – REVISED MAY 2013 www.ti.com ELECTRICAL CHARACTERISTICS (continued) Specifications in standard type face are for TJ = 25°C and those with boldface type apply over the full Operating Temperature Range ( TJ = −40°C to +125°C). Minimum and Maximum limits are specified through test, design, or statistical correlation. Typical values represent the most likely parametric norm at TJ = +25ºC, and are provided for reference purposes only.
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LM3434 www.ti.com SNVS619B – MARCH 2010 – REVISED MAY 2013 TYPICAL PERFORMANCE CHARACTERISTICS Efficiency vs. LED Forward Voltage (VCGND-VEE = 9V) Efficiency vs. LED Forward Voltage (VCGND-VEE = 12V) 97 96 2A 4A 6A 8A 96 94 94 EFFICIENCY (%) EFFICIENCY (%) 95 93 92 91 90 2A 4A 6A 8A 89 88 87 1 2 3 4 5 92 90 88 86 6 84 7 1 2 3 VLED (V) 5 6 7 VLED (V) Figure 2. Figure 3. Efficiency vs. LED Forward Voltage (VCGND-VEE = 14V) VSENSE vs. VADJ (VIN = 3.
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LM3434 SNVS619B – MARCH 2010 – REVISED MAY 2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS (continued) VSENSE vs. Temperature (ADJ = 1.0V) Average LED Current vs. DIM Duty Cycle (30kHz dimming, ILED = 6A nominal) 61 7 AVERAGE LED CURRENT (A) 60.8 60.6 VSENSE (mV) 60.4 60.2 60 59.8 59.6 59.4 59.2 59 -40 -20 0 20 40 60 6 5 4 3 2 1 0 80 0 AMBIENT TEMPERATURE (°C) 10 20 30 40 50 60 70 80 90 100 DIM DUTY CYCLE (%) Figure 8. Figure 9.
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LM3434 www.ti.com SNVS619B – MARCH 2010 – REVISED MAY 2013 OPERATION CURRENT REGULATOR OPERATION The LM3434 is a controller for a Continuous Conduction Buck Converter. Because of its buck topology and operation in the continuous mode, the output current is very well controlled. It only varies within a switching frequency cycle by the inductor ripple current. This ripple current is normally set at 10% of the DC current.
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LM3434 SNVS619B – MARCH 2010 – REVISED MAY 2013 www.ti.com FIXED LED CURRENT The ADJ pin sets VSENSE. Tie ADJ to VIN to use a fixed 60mV internal reference for VSENSE. Select RSENSE to fix the LED current based on the following equation: RSENSE = 60mV/ILED (2) ADJUSTABLE LED CURRENT When tied to an external voltage the ADJ pin sets VSENSE based on the following equation: VSENSE = (VADJ - VCGND)/16.
PAGE 11
LM3434 www.ti.com SNVS619B – MARCH 2010 – REVISED MAY 2013 INDUCTOR SELECTION The most critical inductor parameters are inductance, current rating, and DC resistance. To calculate the inductance, use the desired peak to peak LED ripple current (IRIPPLE), RON, and CON. A reasonable value for IRIPPLE is 10% of ILED. The inductor value is calculated using the following equation: L= 0.
PAGE 12
LM3434 SNVS619B – MARCH 2010 – REVISED MAY 2013 www.ti.com PWM DIM OPERATION The DIM pin of the LM3434 is designed so that it may be controlled using a 1.6V or higher logic signal. The PWM frequency easily accomodates more than 40kHz dimming and can be much faster if needed. If the PWM DIM pin is not used, tie it to CGND or leave it open. The DIM pin is tied to CGND internally through a 100k pull down resistor.
PAGE 13
LM3434 www.ti.com SNVS619B – MARCH 2010 – REVISED MAY 2013 APPLICATION INFORMATION 0.1 PF 44.2k LED ANODE ADJ ADJ EN EN DIM DIM DMO DIMR TON BST2 CSP 270 pF -12V CSN Q3* Q1 HO LED HS 0.47 PF LM3434 BST LED CATHODE Q2 LO 22 PF LS SS 4.7 PF COMP 100 VEE CGND VIN +3.3V 0.01 15 PH VCC 2.2 PF * Only required if PWM dimming is used. GND + 68 PF* 0.01 PF 0.1 PF -12V Figure 13. Up to 10A Output Application Circuit 0.
PAGE 14
LM3434 SNVS619B – MARCH 2010 – REVISED MAY 2013 www.ti.com Table 2. Some Recommended Input/Bypass Capacitors (Others May Be Used) Manufacturer Capacitor Contact Information Vishay Sprague 293D, 592D, and 595D series tantalum www.vishay.com 407-324-4140 Taiyo Yuden High capacitance MLCC ceramic www.t-yuden.com 408-573-4150 Cornell Dubilier ESRD seriec Polymer Aluminum Electrolytic SPV and AFK series V-chip series www.cde.com MuRata High capacitance MLCC ceramic www.murata.com Table 3.
PAGE 15
LM3434 www.ti.com SNVS619B – MARCH 2010 – REVISED MAY 2013 REVISION HISTORY Changes from Revision A (May 2013) to Revision B • Page Changed layout of National Data Sheet to TI format ..........................................................................................................
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PACKAGE OPTION ADDENDUM www.ti.
PAGE 17
PACKAGE MATERIALS INFORMATION www.ti.com 8-May-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant LM3434SQ/NOPB WQFN RTW 24 1000 178.0 12.4 4.3 4.3 1.3 8.0 12.0 Q1 LM3434SQX/NOPB WQFN RTW 24 4500 330.0 12.4 4.3 4.3 1.3 8.0 12.
PAGE 18
PACKAGE MATERIALS INFORMATION www.ti.com 8-May-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM3434SQ/NOPB WQFN RTW 24 1000 210.0 185.0 35.0 LM3434SQX/NOPB WQFN RTW 24 4500 367.0 367.0 35.
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MECHANICAL DATA RTW0024A SQA24A (Rev B) www.ti.
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IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.