LM3424BKBSTEVAL National Semiconductor, LM3424BKBSTEVAL Datasheet
LM3424BKBSTEVAL
Specifications of LM3424BKBSTEVAL
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LM3424BKBSTEVAL Summary of contents
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... The LM3424Q is an Automotive Grade product that is AEC- Q100 grade 1 qualified. Typical Boost Application Circuit © 2009 National Semiconductor Corporation LM3424 Features ■ LM3424Q is an Automotive Grade product that is AEC- Q100 grade 1 qualified (-40° ...
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Connection Diagram Ordering Information Order Spec. Package Type Number LM3424MH NOPB TSSOP-20 EP LM3424MHX NOPB TSSOP-20 EP LM3424QMH NOPB TSSOP-20 EP LM3424QMHX NOPB TSSOP-20 EP *Automotive Grade (Q) product incorporates enhanced manufacturing and support processes for the automotive market, including ...
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Pin Descriptions Pin Name Description V 1 Input Voltage Enable 3 COMP Compensation 4 CSH Current Sense High 5 RT Resistor Timing Dimming Input / 6 nDIM Under-Voltage Protection 7 SS Soft-start 8 TGAIN Temp Foldback Gain ...
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... Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications EN, nDIM IN OVP, HSP, HSN TREF, TSENSE, TGAIN, S COMP, CSH, RT, SLOPE GATE, DDRV - continuous Electrical Characteristics Specifications in standard type face are for T Range ( T = − ...
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Symbol Parameter OSCILLATOR (RT) f Switching Frequency SW V Sync Threshold RT-SYNC PWM COMPARATOR V COMP to PWM Offset - No CP-BASE Slope Compensation SLOPE COMPENSATION (SLOPE) ΔV Slope Compensation CP Amplitude CURRENT LIMIT (IS) V Current Limit Threshold LIM ...
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Symbol Parameter THERMAL SHUTDOWN T Thermal Shutdown SD Threshold T Thermal Shutdown HYS Hysteresis THERMAL RESISTANCE θ Junction to Ambient JA Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur, including inoperability and degradation ...
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Typical Performance Characteristics Boost Efficiency vs. Input Voltage V = 32V (9 LEDs) (Note O Boost LED Current vs. Input Voltage V = 32V (9 LEDs) (Note O Analog Dimming V = 21V (6 LEDs 24V O IN ...
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V vs. Junction Temperature CSH V vs. Junction Temperature S t vs. Junction Temperature ON-MIN www.national.com V vs. Junction Temperature CC 300857b0 V vs. Junction Temperature LIM 300857b2 f vs. Junction Temperature SW 300857b4 8 300857b1 300857b3 30085701 ...
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I vs. Junction Temperature kΩ 0.5V; V GAIN TSENSE TREF Ideal Thermal Foldback - Varied Slope 49.9 kΩ REF1 REF2 NTC-BK BIAS = 1.5V 30085702 Ideal Thermal ...
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Block Diagram Theory of Operation The LM3424 is an N-channel MosFET (NFET) controller for buck, boost and buck-boost current regulators which are ideal for driving LED loads. The controller has wide input voltage range allowing for regulation of a variety ...
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FIGURE 1. Ideal CCM Regulator Inductor Current i CURRENT REGULATORS Current regulators can be designed to accomplish three basic functions: buck, boost, and buck-boost. All three topologies in their most basic form contain a main switching MosFET, a recirculating diode, ...
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AVERAGE LED CURRENT To first understand how the LM3424 regulates LED current, the thermal foldback functionality will be ignored. shows the physical implementation of the LED current sense circuitry assuming the thermal foldback circuitry is a simple current source which, ...
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THERMAL FOLDBACK / ANALOG DIMMING Thermal foldback is necessary in many applications due to the extreme temperatures created in LED environments. In general, two functions are necessary: a temperature break- point (T ) after which the nominal operating current needs ...
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If an analog temperature sensor such as the LM94022 is used, then R and the NTC are not necessary and BIAS V will be the direct voltage output of the sensor. TENSE Since the NTC is not usually local to ...
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CURRENT SENSE/CURRENT LIMIT The LM3424 achieves peak current mode control using a comparator that monitors the main MosFET (Q1) transistor current, comparing it with the COMP pin voltage as shown in Figure 7. Further, it incorporates a cycle-by-cycle over-current protection ...
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CONTROL LOOP COMPENSATION The LM3424 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 output capacitor and, in the boost and ...
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To mitigate this problem, a compensator should be designed to give adequate phase margin (above 45°) at the crossover frequency. A simple compensator using a single capacitor at the COMP pin (C ) will add a dominant pole to the ...
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Then COMP will clamp to SS, forcing COMP to rise (the last 200 mV before switching begins) according to the C ing time (t ) which can be estimated as: SS The system start-up time ( SU-SS ...
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PWM DIMMING The active low nDIM pin can be driven with a PWM signal which controls the main NFET and the dimming FET (dim- FET). The brightness of the LEDs can be varied by modulat- ing the duty cycle of ...
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Design Considerations This section describes the application level considerations when designing with the LM3424. For corresponding calcu- lations, refer to the Design Guide section. INDUCTOR The inductor (L1) is the main energy storage device in a switching regulator. Depending on ...
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MAIN MosFET / DIMMING MosFET The LM3424 requires an external NFET (Q1) as the main power MosFET for the switching regulator recommend have a voltage rating at least 15% higher than the maximum transistor voltage to ...
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Basic Topology Schematics BOOST REGULATOR (V < www.national.com 22 30085722 ...
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BUCK REGULATOR (V > 30085751 www.national.com ...
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BUCK-BOOST REGULATOR www.national.com 24 30085750 ...
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Design Guide Refer to Basic Topology Schematics section. SPECIFICATIONS Number of series LEDs: N Single LED forward voltage: V LED Single LED dynamic resistance: r LED Nominal input voltage Input voltage range IN-MAX IN-MIN Switching ...
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The minimum allowable inductor RMS current rating (I can be calculated as: Buck Boost and Buck-boost 6. LED RIPPLE CURRENT Set the nominal LED ripple current (Δi the output capacitance ( Buck Boost and Buck-boost To set the ...
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And the uncompensated DC loop gain (T Buck Boost Buck-boost For all topologies, the primary method of compensation is to place a low frequency dominant pole (ω that there is ample phase margin at the crossover frequency. This is accomplished ...
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The current rating should be at least 10% higher than the maximum average NFET current (I T-MAX Buck Boost and Buck-boost Approximate the nominal RMS transistor current (I Buck Boost and Buck-boost Given an NFET with on-resistance (R nominal power ...
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SOFT-START For all topologies, if soft-start is desired, find the start-up time without Then, if the desired total start-up time ( solve for the base start-up time (t SU SU-SS-BASE that a ...
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Design Example DESIGN #1 - BUCK-BOOST Application SPECIFICATIONS 3.5V LED r = 325 mΩ LED V = 24V 10V IN-MIN V = 70V IN-MAX f = 500 kHz 100 ...
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OPERATING POINT Solve for V and Solve for D, D and D : MAX MIN 2. SWITCHING FREQUENCY Solve for The closest standard resistor is 14.3 kΩ therefore f The ...
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OUTPUT CAPACITANCE Solve for The closest capacitance totals 40 µF therefore Δi Determine minimum allowable RMS current rating: The chosen components from step 6 are: 7. PEAK CURRENT LIMIT Solve for R : LIM The closest ...
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INPUT CAPACITANCE Solve for the minimum minimize power supply interaction a 200% larger capaci- tance of approximately 20 µF is used, therefore the actual Δv is much lower. Since high voltage ceramic capacitor IN-PP selection ...
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SOFT-START Solve for less than t , solve for t SU TSU SU-SS-BASE DESIGN #1 Bill of Materials Qty Part ID 1 LM3424 1 C BYP CMP NTC 1 ...
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Applications Information The following designs are provided as reference circuits. For a specific design, the steps in the Design Procedure section should be performed. In all designs filter (0.1 µF, 10Ω) is recommended at VIN placed as close ...
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DESIGN #2 Bill of Materials Qty Part ID 1 LM3424 1 C BYP 1 C CMP OUT NTC REF ...
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DESIGN #3 - BUCK-BOOST Application Features • Input: 10V to 30V • Output: 4 LEDs at 2A • PWM Dimming up to 10kHz • Analog Dimming • 600 kHz Switching Frequency 37 300857h6 www.national.com ...
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DESIGN #3 Bill of Materials Qty Part ID 1 LM3424 BYP CMP REF NTC 4 C OUT ...
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DESIGN #4 - BOOST Application Features • Input: 18V to 38V • Output: 12 LEDs at 700mA • 85°C - 125°C Thermal Foldback • Analog Dimming • 700 kHz Switching Frequency 39 300857h7 www.national.com ...
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DESIGN #4 Bill of Materials Qty Part ID 1 LM3424 1 C BYP CMP REF 1 C NTC OUT ...
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DESIGN #5 - BUCK-BOOST Application Features • Input: 10V to 70V • Output: 6 LEDs at 500mA • PWM Dimming kHz • 5 sec Fade-up • MosFET R Sensing DS-ON • 700 kHz Switching Frequency 41 300857h9 ...
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DESIGN #5 Bill of Materials Qty Part ID 1 LM3424 BYP CMP REF NTC 4 C OUT ...
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DESIGN #6 - BUCK Application Features • Input: 15V to 50V • Output: 3 LEDS AT 1.25A • PWM Dimming kHz • Analog Dimming • 700 kHz Switching Frequency 43 300857h8 www.national.com ...
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DESIGN #6 Bill of Materials Qty Part ID 1 LM3424 1 C BYP CMP DIM NTC OUT REF SS ...
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DESIGN #7 - BUCK-BOOST Application Features • Input: 15V to 60V • Output: 8 LEDs at 2.5A • 80°C - 110°C Thermal Foldback • 500 kHz Switching Frequency • External Synchronization > 500 kHz 45 300857i0 www.national.com ...
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DESIGN #7 Bill of Materials Qty Part ID 1 LM3424 FLT 1 C BYP CMP NTC OUT REF ...
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DESIGN #8 - SEPIC Application Features • Input 36V • Output: 5 LEDs at 750mA • 60°C - 120°C Thermal Foldback • PWM Dimming kHz • 500 kHz Switching Frequency 47 300857i8 www.national.com ...
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DESIGN #8 Bill of Materials Qty Part ID 1 LM3424 1 C BYP CMP NTC OUT 1 C SEP REF ...
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Physical Dimensions inches (millimeters) unless otherwise noted For Ordering, Refer to Ordering Information Table TSSOP-20 Pin EP Package (MXA) NS Package Number MXA20A 49 www.national.com ...
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