Related Manuals for Texas Instruments LM3429
Summary of Contents for Texas Instruments LM3429
- Page 1 LM3429 LM3429 LM3429Q1 N-Channel Controller for Constant Current LED Drivers Literature Number: SNVS616F...
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Page 2: General Description
Q100 grade 1 qualified (-40°C to +125°C operating boost, buck-boost and SEPIC topologies. This flexibility, junction temperature) ■ along with an input voltage rating of 75V, makes the LM3429 range from 4.5V to 75V ideal for illuminating LEDs in a very diverse, large family of ■... -
Page 3: Connection Diagram
Connection Diagram 30094404 14-Lead TSSOP EP Ordering Information Order Number Spec. Package Type NSC Package Supplied As Features Drawing LM3429MH NOPB TSSOP-14 EP MXA14A 94 Units, Rail LM3429MHX NOPB TSSOP-14 EP MXA14A 2500 Units, Tape and Reel LM3429Q1MH NOPB TSSOP-14 EP MXA14A 94 Units, Rail AEC-Q100 Grade 1... -
Page 4: Absolute Maximum Ratings
PGND -0.3V to 0.3V Absolute Maximum Ratings (Note -2.5V to 2.5V for 100 ns If Military/Aerospace specified devices are required, Maximum Junction Internally Limited please contact the National Semiconductor Sales Office/ Temperature Distributors for availability and specifications. Storage Temperature Range −65°C to +150°C , nDIM -0.3V to 76.0V... - Page 5 Symbol Parameter Conditions Units (Note (Note (Note PWM COMPARATOR COMP to PWM Offset CURRENT LIMIT (IS) Current Limit Threshold Delay to Output Leading Edge Blanking ON-MIN Time HIGH SIDE TRANSCONDUCTANCE AMPLIFIER Input Bias Current µA Transconductance mA/V Input Offset Current -1.5 µA Input Offset Voltage...
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Page 6: Typical Performance Characteristics
Typical Performance Characteristics =+25°C and V = 14V unless otherwise specified Boost Efficiency vs. Input Voltage Buck-Boost Efficiency vs. Input Voltage = 32V (9 LEDs) (Note = 20V (6 LEDs) (Note 300944b5 300944b6 Boost LED Current vs. Input Voltage Buck-boost LED Current vs. Input Voltage (Note (Note = 32V (9 LEDs) - Page 7 vs. Junction Temperature vs. Junction Temperature 300944b0 300944b1 vs. Junction Temperature vs. Junction Temperature 300944b3 300944b2 vs. Junction Temperature ON-MIN 300944b4 www.national.com...
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Page 8: Block Diagram
The LM3429 can then nal control loop compensation, while providing an inherent be used to drive all three basic topologies as shown in the cycle-by-cycle current limit. -
Page 9: Switching Frequency
(f PREDICTIVE OFF-TIME (PRO) CONTROL PRO control is used by the LM3429 to control I . It is a combination of average peak current control and a one-shot off-timer that varies with input voltage. The LM3429 uses peak current control to regulate the average LED current through an array of HBLEDs. - Page 10 HSP and HSN are tied to GND. For all topologies, the C capacitor is recommended to be 1 nF and should be located very close to the LM3429. 30094457 FIGURE 4. LED Current Sense Circuitry...
- Page 11 ANALOG DIMMING CURRENT SENSE/CURRENT LIMIT The CSH pin can be used to analog dim the LED current by The LM3429 achieves peak current mode control using a adjusting the current sense voltage (V ). There are several comparator that monitors the MosFET transistor current,...
- Page 12 CONTROL LOOP COMPENSATION And the right half plane zero (ω ) is: The LM3429 control loop is modeled like any current mode controller. Using a first order approximation, the uncompen- sated loop can be modeled as a single pole created by the...
- Page 13 ) of the error amplifier (typically 5 MΩ): FIGURE 10. Over-Voltage Protection Circuitry The LM3429 can be configured to detect an output (or input) over-voltage condition via the OVP pin. The pin features a precision 1.24V threshold with 20 µA (typical) of hysteresis...
- Page 14 PWM dimming and UVLO PULSE in seconds. STARTUP REGULATOR (V LDO) The LM3429 includes a high voltage, low dropout (LDO) bias regulator. When power is applied, the regulator is enabled and sources current into an external capacitor connected to PWM DIMMING the V pin.
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Page 15: Design Considerations
0.1 µF ceramic capacitor placed as close as pos- sible to the pin. In situations where the bulk input capacitance may be far from the LM3429 device, a 10Ω series resistor can be placed between the bulk input capacitance and the bypass capacitor, creating a 150 kHz filter to eliminate undesired high frequency noise coupling. -
Page 16: Circuit Layout
In some applications the LED or LED array can be far away transistor voltage to ensure safe operation during the ringing (several inches or more) from the LM3429, or on a separate of the switch node and a current rating at least 10% higher PCB connected by a wiring harness. - Page 17 Basic Topology Schematics BOOST REGULATOR (V < V 30094422 BUCK REGULATOR (V > V 30094451 www.national.com...
- Page 18 BUCK-BOOST REGULATOR 30094450 www.national.com...
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Page 19: Design Guide
Buck (Constant Ripple vs. V Design Guide Refer to Basic Topology Schematics section. SPECIFICATIONS Number of series LEDs: N Boost and Buck-boost Single LED forward voltage: V Single LED dynamic resistance: r Nominal input voltage: V Input voltage range: V IN-MAX IN-MIN Switching frequency: f... -
Page 20: Peak Current Limit
5. LED RIPPLE CURRENT Where the pole (ω ) is approximated: Set the nominal LED ripple current (Δi ), by solving for LED-PP Buck the output capacitance (C Buck Boost Boost and Buck-boost Buck-boost To set the worst case LED ripple current, use D when solving for C The minimum allowable RMS output capacitor current rating... -
Page 21: Input Capacitance
A high frequency compensation pole (ω ) can be used to Buck-boost attenuate switching noise and provide better gain margin. As- = 10Ω, C suming R is calculated according to the higher value of the pole and the RHP zero of the system (shown as a maximizing function): 9. - Page 22 The current rating should be at least 10% higher than the 12. INPUT UVLO maximum average diode current (I For all topologies, input UVLO is programmed with the turn- D-MAX on threshold voltage (V ) and the desired hysteresis TURN-ON Buck Method #1: If no PWM dimming is required, a two resistor network can be used.
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Page 23: Design Example
Design Example #1 BUCK-BOOST APPLICATION - 6 LEDs at 1A 300944i1 Solve for D, D', D , and D SPECIFICATIONS N = 6 = 3.5V = 325 mΩ = 24V = 10V IN-MIN = 70V IN-MAX = 700 kHz = 100 mV = 1A Δi = 500 mA... - Page 24 3. AVERAGE LED CURRENT 5. OUTPUT CAPACITANCE Solve for R Solve for C Assume R = 12.4 kΩ and solve for R The closest standard capacitor is 6.8 µF therefore the actual Δi LED-PP The closest standard resistor for R is actually 0.1Ω...
- Page 25 is approximated: 9. NFET Determine minimum Q1 voltage rating and current rating: To ensure stability, calculate ω A 100V NFET is chosen with a current rating of 32A due to the low R = 50 mΩ. Determine I and P DS-ON T-RMS Solve for C...
- Page 26 12. OUTPUT OVLO Solve for R The chosen components from step 12 are: Design #1 Bill of Materials Part ID Part Value Manufacturer Part Number LM3429 Boost controller LM3429MH 0.22 µF X7R 10% 25V MURATA GRM21BR71E224KA01L 2.2 µF X7R 10% 16V MURATA GRM21BR71C225KA12L 0.1 µF X7R 10% 25V...
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Page 27: Applications Information
DESIGN #2: BOOST PWM DIMMING APPLICATION - 9 LEDs at 1A 300944h5 Design #2 Bill of Materials Part ID Part Value Manufacturer Part Number LM3429 Boost controller LM3429MH 0.1 µF X7R 10% 25V MURATA GRM21BR71E104KA01L 2.2 µF X7R 10% 16V... - Page 28 DESIGN #3: BUCK-BOOST ANALOG DIMMING APPLICATION - 4 LEDs at 2A 300944h6 Design #3 Bill of Materials Part ID Part Value Manufacturer Part Number LM3429 Boost controller LM3429MH 1.0 µF X7R 10% 10V MURATA GRM21BR71A105KA01L 2.2 µF X7R 10% 16V...
- Page 29 DESIGN #4: BOOST ANALOG DIMMING APPLICATION - 12 LEDs at 700mA 300944h7 Design #4 Bill of Materials Part ID Part Value Manufacturer Part Number LM3429 Boost controller LM3429MH 1.0 µF X7R 10% 10V MURATA GRM21BR71A105KA01L 2.2 µF X7R 10% 16V...
- Page 30 DESIGN #5: BUCK-BOOST PWM DIMMING APPLICATION - 6 LEDs at 500mA 300944h9 Design #5 Bill of Materials Part ID Part Value Manufacturer Part Number LM3429 Boost controller LM3429MH 0.68 µF X7R 10% 25V MURATA GRM21BR71E684KA88L 2.2 µF X7R 10% 16V...
- Page 31 DESIGN #6: BUCK APPLICATION - 3 LEDS AT 1.25A 300944h8 Design #6 Bill of Materials Part ID Part Value Manufacturer Part Number LM3429 Boost controller LM3429MH 0.015 µF X7R 10% 50V MURATA GRM21BR71H153KA01L 2.2 µF X7R 10% 16V MURATA GRM21BR71C225KA12L 0.01 µF X7R 10% 50V...
- Page 32 DESIGN #7: BUCK-BOOST THERMAL FOLDBACK APPLICATION - 8 LEDs at 2.5A 300944i0 Design #7 Bill of Materials Part ID Part Value Manufacturer Part Number LM3429 Boost controller LM3429MH 0.1 µF X7R 10% 25V MURATA GRM21BR71E104KA01L 2.2 µF X7R 10% 16V...
- Page 33 DESIGN #8: SEPIC APPLICATION - 5 LEDs at 750mA 300944i8 Design #8 Bill of Materials Part ID Part Value Manufacturer Part Number LM3429 Boost controller LM3429MH 0.47 µF X7R 10% 25V MURATA GRM21BR71E474KA01L 2.2 µF X7R 10% 16V MURATA GRM21BR71C225KA12L 0.1 µF X7R 10% 25V...
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Page 34: Physical Dimensions
Physical Dimensions inches (millimeters) unless otherwise noted TSSOP-14 Pin EP Package (MXA) For Ordering, Refer to Ordering Information Table NS Package Number MXA14A www.national.com... - Page 35 Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: www.national.com Products Design Support Amplifiers www.national.com/amplifiers WEBENCH® Tools www.national.com/webench Audio www.national.com/audio App Notes www.national.com/appnotes Clock and Timing www.national.com/timing Reference Designs www.national.com/refdesigns Data Converters www.national.com/adc Samples www.national.com/samples...
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Page 36: Important Notice
IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.