NSI50350AST3G Constant Current Regulator & LED Driver 50 V, 350 mA + 10%, 5.8 W Package The linear constant current regulator (CCR) is a simple, economical and robust device designed to provide a cost−effective solution for regulating current in LEDs. The CCR is based on Self−Biased Transistor (SBT) technology and regulates current over a wide voltage range. It is designed with a negative temperature coefficient to protect LEDs from thermal runaway at extreme voltages and currents. The CCR turns on immediately and is at 20% of regulation with only 0.5 V Vak. It requires no external components allowing it to be designed as a high or low−side regulator. The high anode−cathode voltage rating withstands surges common in Automotive, Industrial and Commercial Signage applications. The CCR comes in thermally robust packages and is qualified to AEC−Q101 standard and UL94−V0 Certified. Also available in DPAK: NSI50350ADT4G. http://onsemi.com Ireg(SS) = 350 mA @ Vak = 7.5 V Anode 2 Cathode 1 Features • • • • • • • • Typical Applications • Automobile: Chevron Side Mirror Markers, Cluster, Display & Instrument Backlighting, CHMSL, Map Light • AC Lighting Panels, Display Signage, Decorative Lighting, Channel • • Lettering Application Note AND8349/D − Automotive CHMSL Application Notes AND8391/D, AND9008/D − Power Dissipation Considerations Mechanical Characteristics • CASE: Void-free, transfer-molded, thermosetting plastic • • • • • 1 Robust Power Package: 5.8 W Wide Operating Voltage Range Immediate Turn−On Voltage Surge Suppressing − Protecting LEDs AEC−Q101 Qualified and PPAP Capable, UL94−V0 Certified SBT (Self−Biased Transistor) Technology Negative Temperature Coefficient These Devices are Pb−Free, Halogen Free/BFR Free and are RoHS Compliant FINISH: All external surfaces are corrosion resistant and leads are readily solderable MAXIMUM CASE TEMPERATURE FOR SOLDERING PURPOSES: 260°C for 10 seconds LEADS: Modified L−Bend providing more contact area to bond pads POLARITY: Cathode indicated by molded polarity notch MOUNTING POSITIONS: Any © Semiconductor Components Industries, LLC, 2012 May, 2012 − Rev. 3 1 2 SMC CASE 403 MARKING DIAGRAM 1 AYWW 350AG G 2 350A = Specific Device Code A = Assembly Location Y = Year WW = Work Week G = Pb−Free Package (Note: Microdot may be in either location) ORDERING INFORMATION Device Package Shipping† NSI50350AST3G SMC (Pb−Free) 2500 / Tape & Reel †For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specifications Brochure, BRD8011/D. Publication Order Number: NSI50350AS/D NSI50350AST3G MAXIMUM RATINGS (TA = 25°C unless otherwise noted) Rating Anode−Cathode Voltage Reverse Voltage Operating and Storage Junction Temperature Range ESD Rating: Human Body Model Machine Model Symbol Value Unit Vak Max 50 V VR 500 mV TJ, Tstg −55 to +175 °C ESD Class 3B (8000 V) Class C (400 V) Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect device reliability. ELECTRICAL CHARACTERISTICS (TA = 25°C unless otherwise noted) Characteristic Symbol Min Typ Max Unit Steady State Current @ Vak = 7.5 V (Note 1) Ireg(SS) 315 350 385 mA 405.5 460 516.5 mA Voltage Overhead (Note 2) Voverhead Pulse Current @ Vak = 7.5 V (Note 3) Ireg(P) 1.8 V 1. Ireg(SS) steady state is the voltage (Vak) applied for a time duration ≥ 300 sec, using 900 mm2 DENKA K1, 1.5 mm Al, 2kV Thermally conductive dielectric, 2 oz. Cu (or equivalent), in still air. 2. Voverhead = Vin − VLEDs. Voverhead is typical value for 70% Ireg(SS). 3. Ireg(P) non−repetitive pulse test. Pulse width t ≤ 360 msec. THERMAL CHARACTERISTICS Characteristic Symbol Max Unit PD 3112 20.75 mW mW/°C Thermal Resistance, Junction−to−Ambient (Note 4) RθJA 48.2 °C/W Thermal Reference, Junction−to−Tab (Note 4) RψJL PD 8.7 °C/W 4225 28.17 mW mW/°C Total Device Dissipation (Note 4) TA = 25°C Derate above 25°C Total Device Dissipation (Note 5) TA = 25°C Derate above 25°C Thermal Resistance, Junction−to−Ambient (Note 5) RθJA 35.5 °C/W Thermal Reference, Junction−to−Tab (Note 5) RψJL 8.0 °C/W PD 5119 34.13 mW mW/°C Thermal Resistance, Junction−to−Ambient (Note 6) RθJA 29.3 °C/W Thermal Reference, Junction−to−Tab (Note 6) RψJL 7.2 °C/W PD 5859 39.06 mW mW/°C Thermal Resistance, Junction−to−Ambient (Note 7) RθJA 25.6 °C/W Thermal Reference, Junction−to−Tab (Note 7) RψJL 6.9 °C/W PD 3061 20.41 mW mW/°C Total Device Dissipation (Note 6) TA = 25°C Derate above 25°C Total Device Dissipation (Note 7) TA = 25°C Derate above 25°C Total Device Dissipation (Note 8) TA = 25°C Derate above 25°C Thermal Resistance, Junction−to−Ambient (Note 8) RθJA 49 °C/W Thermal Reference, Junction−to−Tab (Note 8) RψJL 15.1 °C/W NOTE: Lead measurements are made by non−contact methods such as IR with treated surface to increase emissivity to 0.9. Lead temperature measurement by attaching a T/C may yield values as high as 30% higher °C/W values based upon empirical measurements and method of attachment. 4. 400 mm2, see below PCB description, still air. 5. 900 mm2, see below PCB description, still air. 6. 1600 mm2, see below PCB description, still air. 7. 2500 mm2, see below PCB description, still air. (For NOTES 4−7: PCB is DENKA K1, 1.5 mm Al, 2kV Thermally conductive dielectric, 2 oz. Cu, or equivalent). 8. 1000 mm2, FR4, 3 oz Cu, still air. http://onsemi.com 2 NSI50350AST3G TYPICAL PERFORMANCE CURVES (Minimum DENKA K1 @ 900 mm2, 1.5 mm Al, 2kV Thermally conductive dielectric, 2 oz. Cu, or equivalent) Ireg(SS), STEADY STATE CURRENT (mA) Ireg, CURRENT REGULATION (mA) 400 350 300 250 200 150 100 50 0 TA = 25°C −50 −10 0 10 20 30 50 40 60 Ireg(SS), STEADY STATE CURRENT (mA) Ireg(P), PULSE CURRENT (mA) TA = 85°C 300 350 300 250 200 Non−Repetitive Pulse Test TJ, maximum die temperature limit 175°C 200 150 100 50 0 DC Test Steady State, Still Air 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 380 3 4 5 6 8 7 9 10 11 12 13 14 15 Vak @ 7.5 V TA = 25°C 370 360 350 340 330 320 310 400 410 420 430 440 450 460 470 480 490 500 510 520 Ireg(P), PULSE CURRENT (mA) Figure 3. Pulse Current (Ireg(P)) vs. Anode−Cathode Voltage (Vak) Figure 4. Steady State Current vs. Pulse Current Testing 450 9000 Vak @ 7.5 V TA = 25°C 440 430 PD, POWER DISSIPATION (mW) Ireg, CURRENT REGULATION (mA) 2 390 Vak, ANODE−CATHODE VOLTAGE (V) 420 410 400 390 380 370 360 350 0 ≈−0.847 mA/°C typ 250 Figure 2. Steady State Current (Ireg(SS)) vs. Anode−Cathode Voltage (Vak) 400 340 ≈−0.773 mA/°C typ Figure 1. General Performance Curve for CCR TA = 25°C 1 TA = 25°C 350 Vak, ANODE−CATHODE VOLTAGE (V) 450 150 TA = −40°C 400 Vak, ANODE−CATHODE VOLTAGE (V) 550 500 450 50 100 150 200 250 300 2500 mm2, Denka K1, 2 oz 8000 7000 1600 mm2, Denka K1, 2 oz 6000 5000 4000 3000 2000 900 mm2, Denka K1, 2 oz 1000 0 −40 350 400 mm2, Denka K1, 2 oz 1000 mm2, FR4, 3 oz 0 40 80 TIME (s) TA, AMBIENT TEMPERATURE (°C) Figure 5. Current Regulation vs. Time Figure 6. Power Dissipation vs. Ambient Temperature @ TJ = 1755C http://onsemi.com 3 120 NSI50350AST3G APPLICATIONS INFORMATION The CCR is a self biased transistor designed to regulate the current through itself and any devices in series with it. The device has a slight negative temperature coefficient, as shown in Figure 2 – Tri Temp. (i.e. if the temperature increases the current will decrease). This negative temperature coefficient will protect the LEDS by reducing the current as temperature rises. The CCR turns on immediately and is typically at 20% of regulation with only 0.5 V across it. The device is capable of handling voltage for short durations of up to 50 V so long as the die temperature does not exceed 175°C. The determination will depend on the thermal pad it is mounted on, the ambient temperature, the pulse duration, pulse shape and repetition. Single LED String The CCR can be placed in series with LEDs as a High Side or a Low Side Driver. The number of the LEDs can vary from one to an unlimited number. The designer needs to calculate the maximum voltage across the CCR by taking the maximum input voltage less the voltage across the LED string (Figures 7 and 8). Figure 8. Higher Current LED Strings Two or more fixed current CCRs can be connected in parallel. The current through them is additive (Figure 9). Figure 7. Figure 9. http://onsemi.com 4 NSI50350AST3G Other Currents LEDs on and off for a portion of a single cycle. This on/off cycle is called the Duty cycle (D) and is expressed by the amount of time the LEDs are on (Ton) divided by the total time of an on/off cycle (Ts) (Figure 12). The adjustable CCR can be placed in parallel with any other CCR to obtain a desired current. The adjustable CCR provides the ability to adjust the current as LED efficiency increases to obtain the same light output (Figure 10). Figure 12. The current through the LEDs is constant during the period they are turned on resulting in the light being consistent with no shift in chromaticity (color). The brightness is in proportion to the percentage of time that the LEDs are turned on. Figure 13 is a typical response of Luminance vs Duty Cycle. 6000 5000 ILLUMINANCE (lx) Figure 10. 4000 Dimming using PWM The dimming of an LED string can be easily achieved by placing a BJT in series with the CCR (Figure 11). 3000 2000 Lux Linear 1000 0 0 10 20 30 40 50 60 70 DUTY CYCLE (%) 80 90 100 Figure 13. Luminous Emmitance vs. Duty Cycle Reducing EMI Designers creating circuits switching medium to high currents need to be concerned about Electromagnetic Interference (EMI). The LEDs and the CCR switch extremely fast, less than 100 nanoseconds. To help eliminate EMI, a capacitor can be added to the circuit across R2. (Figure 11) This will cause the slope on the rising and falling edge on the current through the circuit to be extended. The slope of the CCR on/off current can be controlled by the values of R1 and C1. The selected delay / slope will impact the frequency that is selected to operate the dimming circuit. The longer the delay, the lower the frequency will be. The delay time should not be less than a 10:1 ratio of the minimum on time. The frequency is also impacted by the resolution and dimming steps that are required. With a delay of 1.5 microseconds on the rise and the fall edges, the minimum on time would be 30 microseconds. If the design called for a resolution of 100 dimming steps, then a total duty cycle time (Ts) of 3 milliseconds or a frequency of 333 Hz will be required. Figure 11. The method of pulsing the current through the LEDs is known as Pulse Width Modulation (PWM) and has become the preferred method of changing the light level. LEDs being a silicon device, turn on and off rapidly in response to the current through them being turned on and off. The switching time is in the order of 100 nanoseconds, this equates to a maximum frequency of 10 MHz, and applications will typically operate from a 100 Hz to 100 kHz. Below 100 Hz the human eye will detect a flicker from the light emitted from the LEDs. Between 500 Hz and 20 kHz the circuit may generate audible sound. Dimming is achieved by turning the http://onsemi.com 5 NSI50350AST3G Thermal Considerations P D(MAX) + As power in the CCR increases, it might become necessary to provide some thermal relief. The maximum power dissipation supported by the device is dependent upon board design and layout. Mounting pad configuration on the PCB, the board material, and the ambient temperature affect the rate of junction temperature rise for the part. When the device has good thermal conductivity through the PCB, the junction temperature will be relatively low with high power applications. The maximum dissipation the device can handle is given by: T J(MAX) * T A R qJA Referring to the thermal table on page 2 the appropriate RqJA for the circuit board can be selected. AC Applications The CCR is a DC device; however, it can be used with full wave rectified AC as shown in application notes AND8433/D and AND8492/D and design notes DN05013/D and DN06065/D. Figure 14 shows the basic circuit configuration. Figure 14. Basic AC Application http://onsemi.com 6 NSI50350AST3G PACKAGE DIMENSIONS SMC CASE 403−03 ISSUE E NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. 3. D DIMENSION SHALL BE MEASURED WITHIN DIMENSION P. 4. 403-01 THRU -02 OBSOLETE, NEW STANDARD 403-03. HE E b DIM A A1 b c D E HE L L1 D MIN 1.90 0.05 2.92 0.15 5.59 6.60 7.75 0.76 MILLIMETERS NOM MAX 2.13 2.41 0.10 0.15 3.00 3.07 0.23 0.30 5.84 6.10 6.86 7.11 7.94 8.13 1.02 1.27 0.51 REF MIN 0.075 0.002 0.115 0.006 0.220 0.260 0.305 0.030 INCHES NOM 0.084 0.004 0.118 0.009 0.230 0.270 0.313 0.040 0.020 REF MAX 0.095 0.006 0.121 0.012 0.240 0.280 0.320 0.050 A L L1 c A1 SOLDERING FOOTPRINT* 4.343 0.171 3.810 0.150 2.794 0.110 SCALE 4:1 mm Ǔ ǒinches *For additional information on our Pb−Free strategy and soldering details, please download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D. ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. 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