PT4115B89E

PT4115 30V, 1.2A Step-down High Brightness LED Driver with 5000:1 Dimming GENERAL DESCRIPTION FEATURES The PT4115 is a continuous conduction mode inductive step-down converter, designed for driving single or multiple series connected LED efficiently from a voltage source higher than the total LED chain voltage. The device operates from an input supply between 6V and 30V and provides an externally adjustable output current of up to 1.2A. Depending upon the supply voltage and external components, the PT4115can provide more than 30 watts of output power. The PT4115 includes the power switch and a high-side output current sensing circuit, which uses an external resistor to set the nominal average output current, and a dedicated DIM input accepts either a DC voltage or a wide range of pulsed dimming. Applying a voltage of 0.3V or lower to the DIM pin turns the output off and switches the device into a low current standby state. The PT4115 is available in SOT89-5 and ESOP8 packages.              Simple low parts count Wide input voltage range: 6V to 30V Up to 1.2A output current Single pin on/off and brightness control using DC voltage or PWM Up to 1MHz switching frequency Typical 5% output current accuracy Inherent open-circuit LED protection High efficiency (up to 97%) High-Side Current Sense Hysteretic Control: No Compensation Adjustable Constant LED Current ESOP8 package for large output power application RoHS compliant APPLICATIONS        Low voltage halogen replacement LEDs Automotive lighting Low voltage industrial lighting LED back-up lighting Illuminated signs SELV lighting LCD TV backlighting ORDERING INFORMATION PACKAGE TEMPERATURE RANGE SOT89-5 -40 oC to 85 oC ESOP8 -40 oC to 85 oC ORDERING PART NUMBER PT4115B89E:A type PT4115B89E-B:B type TRANSPORT MEDIA Tape and Reel 1000 units PT4115BSOH:A type PT4115BSOH-B:B type Tape and Reel 2500 units MARKING PT4115 xxxxxX PT4115 xxxxxX Note: xxxxxX Assembly Factory Code Lot Number TYPICAL APPLICATION CIRCUIT VIN RS DC6-30V LED 3W 0.13Ω L 68uH D CIN AC12-18V 100uF VIN DIM CSN SW PT4115 GND China Resources Powtech (Shanghai) Limited PT4115_DS Rev EN_2.9 WWW.CRPOWTECH.COM Page 1 PT4115 30V, 1.2A Step-down High Brightness LED Driver with 5000:1 Dimming PIN ASSIGNMENT 1 VIN 2 SW 3 NC 4 PT4115 CSN 8 DIM 7 GNDA 6 GNDP 5 NC ESOP8 PIN DESCRIPTIONS PIN No. PIN NAMES 1 SW 2 GND 3 DIM 4 CSN Current sense input 5 VIN Input Supply Pin. Must be locally bypassed. - Exposed ESOP8 4,5 DESCRIPTION Switch Output. SW is the drain of the internal N-Ch MOSFET switch. Signal and power ground. Connect directly to ground plane. Logic level dimming input. Drive DIM low to turn off the current regulator. Drive DIM high to enable the current regulator. PAD NC Internally connected to GND. Mount on board for lower thermal resistance. No connection ABSOLUTE MAXIMUM RATINGS (note1) SYMBOL ITEMS VALUE UNIT VIN Supply Voltage -0.3~45 V SW Drain of the internal power switch -0.3~45 V CSN Current sense input (Respect to VIN) +0.3~(-6.0) V DIM Logic level dimming input -0.3~6 V Switch output current 1.5 A Power Dissipation (Note 2) 1.5 W ISW PDMAX PTR θJA Thermal Resistance, SOT89-5 θJA 45 o 40 o C /W PTR Thermal Resistance, ESOP8 TJ Operation Junction Temperature Range -40 to 150 o Storage Temperature -55 to 150 o TSTG ESD Susceptibility (Note 3) China Resources Powtech (Shanghai) Limited PT4115_DS Rev EN_2.9 2 WWW.CRPOWTECH.COM C /W C C kV Page 2 PT4115 30V, 1.2A Step-down High Brightness LED Driver with 5000:1 Dimming RECOMMENDED OPERATING RANGE SYMBOL ITEMS VIN VDD Supply Voltage TOPT Operating Temperature VALUE UNIT 6 ~ 30 V o -40 to +85 C Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Recommended Operating Range indicates conditions for which the device is functional, but do not guarantee specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which guarantee specific performance limits. This assumes that the device is within the Operating Range. Specifications are not guaranteed for parameters where no limit is given, however, the typical value is a good indication of device performance. Note 2: The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX, θJA, and the ambient temperature TA. The maximum allowable power dissipation is PDMAX = (TJMAX - TA)/ θJA or the number given in Absolute Maximum Ratings, whichever is lower. Note 3: Human body model, 100pF discharged through a 1.5kΩ resistor. ELECTRICAL CHARACTERISTICS (Note 4, 5) The following specifications apply for VIN=12V, TA=25 oC, unless specified otherwise. SYMBOL VIN VUVLO VUVLO, HYS FSW ITEMS CONDITIONS Input Voltage Min. Typ. 6 Max. UNIT 30 V Under voltage lock out VIN falling 5.1 V UVLO hysterisis VIN rising 500 mV Max. Switching Frequency 1 MHz Current Sense Mean current sense VCSN VCSN_hys ICSN threshold voltage VIN-VCSN A type 95 98 101 mV B 99 102 105 mV type Sense threshold hysteresis CSN Pin Input Current ±15 % VIN-VCSN=50mV 8 µA VDIM 115mV, the output of CS working. When a voltage applied to DIM falls below comparator switches low and the switch turns off. The the threshold (0.3V nom.), the output switch is turned current flowing on the RS decreases at another rate. off. The internal regulator and voltage reference remain When (VIN-VCSN) < 85mV, the switch turns on again powered during shutdown to provide the reference for and the mean current on the LED is determined by the shutdown circuit. Quiescent supply current during ( 85+2115 mV ) / RS = 100mV / RS . shutdown is nominally 95uA and switch leakage is The high-side current-sensing scheme and on-board Additionally, to ensure the reliability, the PT4115 is current-setting circuitry minimize the number of built with a thermal shutdown (TSD) protection and a external components while delivering LED current with thermal pad. The TSD protests the IC from over ±5% accuracy, using a 1% sense resistor. temperature (160℃). Also the thermal pad enhances The PT4115 allow dimming with a PWM signal at the power dissipation. As a result, the PT4115 can handle a DIM input. A logic level below 0.3V at DIM forces large amount of current safely. below 5uA. PT4115 to turn off the LED and the logic level at DIM must be at least 2.5V to turn on the full LED current. The frequency of PWM dimming ranges from 100Hz to more than 20 kHz. The DIM pin can be driven by an external DC voltage China Resources Powtech (Shanghai) Limited PT4115_DS Rev EN_2.9 WWW.CRPOWTECH.COM Page 5 PT4115 30V, 1.2A Step-down High Brightness LED Driver with 5000:1 Dimming TYPICAL PERFORMANCE CHARACTERISTICS Efficiency1,3 and 7 LEDs 100% L=47uH Rs=0.13ohm 7LEDs Efficiency 95% 90% 3 LEDs 85% 80% 75% 1LED 8 10 12 14 16 18 20 22 24 26 28 30 Supply Voltage Vin(V) Vdim vs Supply Voltage 5.5 5.4 5.3 Vdim(V) 5.2 5.1 5.0 4.9 4.8 4.7 4.6 4.5 5 10 15 20 25 30 Supply Voltage Vin(V) Vdim vs Temperature 5.30 Vdim(V) 5.25 5.20 5.15 5.10 5.05 5.00 -40 -20 0 20 40 60 80 100 120 Temperature(Deg C) China Resources Powtech (Shanghai) Limited PT4115_DS Rev EN_2.9 WWW.CRPOWTECH.COM Page 6 PT4115 30V, 1.2A Step-down High Brightness LED Driver with 5000:1 Dimming Rsw vs Supply Voltage 1.0 Rsw (ohm) 0.9 0.8 0.7 0.6 0.5 0.4 0.3 5 15 25 35 Supply Voltage Vin(V) Supply Current vs Supply Voltage 250 Iin (uA) 200 150 100 50 0 0 5 10 15 20 25 30 Supply Voltage Vin(V) LED Current vs Vdim 800 LED current (mA) 700 R=0.13ohm 600 500 400 300 R=0.33ohm 200 100 0 0 1 2 3 4 Dim Pin Voltage (V) China Resources Powtech (Shanghai) Limited PT4115_DS Rev EN_2.9 WWW.CRPOWTECH.COM Page 7 5 PT4115 30V, 1.2A Step-down High Brightness LED Driver with 5000:1 Dimming Output Current L=27uH Rcs=0.0825ohm Output Current Deviation Output Current 1.22 1.20 1.18 4LEDs 1.16 1.14 7LEDs 6LEDs 1LED 2LEDs 1.12 1.10 5 5LEDs 3LEDs 10 15 20 25 Output Current L=27uH Rcs=0.0825ohm 3% 1.24 2% 1% 0% -1% -3% -4% -5% -6% 1LED 5LEDs -7% -8% 30 4LEDs -2% 2LEDs 5 3LEDs 10 15 Supply Voltage(V) 2LEDs Duty Cycle 80% 70% 4LEDs 5LEDs 6LEDs 7LEDs 1LED 50% 40% 30% 20% 10% 900 800 700 600 500 400 10 15 20 25 4LEDs 300 7LEDs 30 5 10 Output Current L=47uH Rcs=0.13ohm Output Current Deviation Output Current(mA) 780 770 760 750 740 7LEDs 710 4LEDs 2LEDs 720 5LEDs 6LEDs 3LEDs 10 15 20 PT4115_DS Rev EN_2.9 30 2% 0% 25 30 7LEDs -2% 1LED -4% 4LEDs 5LEDs 6LEDs 2LEDs 3LEDs 5 10 15 20 25 30 Supply Voltage(V) Supply Voltage Vin(V) China Resources Powtech (Shanghai) Limited 25 4% -6% 5 20 Output Current L=47uH Rcs=0.13ohm 6% 790 730 1LED 15 Supply Voltage Vin(V) Supply Voltage Vin(V) 800 5LEDs 6LEDs 200 1LED 2LEDs 3LEDs 100 0 5 30 Switching Frequency L=27uH R=0.0825ohm 60% 0% 25 1000 Switching Frequency(kHZ) 3LEDs 90% 20 Supply Voltge(V) Duty Cycle L=27uH R=0.0825ohm 100% 6LEDs 7LEDs WWW.CRPOWTECH.COM Page 8 PT4115 30V, 1.2A Step-down High Brightness LED Driver with 5000:1 Dimming Duty Cycle L=47uH Rcs=0.13ohm 3LEDs 90% 5LEDs Switch Frequency L=47uH Rcs=0.13ohm 900 6LEDs Switch Frequency(kHz) 100% 7LEDs 4LEDs Duty Cycle 80% 2LEDs 70% 60% 50% 40% 30% 1LED 20% 10% 800 700 600 500 400 1LED 4LEDs 300 5LEDs 2LEDs 200 6LEDs 3LEDs 100 7LEDs 0% 8 0 10 12 14 16 18 20 22 24 26 28 30 8 10 12 Supply Voltage Vin(V) 14 16 18 20 22 24 26 28 30 Supply Voltage Vin(V) Output Current L=100uH Rcs=0.33ohm Output Current Deviation 8% 6% 4% 2% 0% -2% 1LED -4% -6% 2LEDs 4LEDs 3LEDs 5 10 15 5LEDs 20 6LEDs 7LEDs 25 30 Supply Voltage Duty Cycle L=100uH R=0.33ohm 80% 3LEDs Duty Cycle 70% 5LEDs 4LEDs 6LEDs 1000 7LEDs Switch Frequency(kHz) 90% 2LEDs 60% 50% 1LED 40% 30% 20% 10% 0% 5 10 15 20 25 Supply Voltage Vin(V) China Resources Powtech (Shanghai) Limited PT4115_DS Rev EN_2.9 30 Switch Frequency L=100uH R=0.33ohm 900 800 700 600 500 2LEDs 4LEDs 400 300 7LEDs 3LEDs 1LED 200 5LEDs 6LEDs 100 0 5 10 15 20 25 30 Supply Voltage Vin(V) WWW.CRPOWTECH.COM Page 9 PT4115 30V, 1.2A Step-down High Brightness LED Driver with 5000:1 Dimming China Resources Powtech (Shanghai) Limited PT4115_DS Rev EN_2.9 WWW.CRPOWTECH.COM Page 10 PT4115 30V, 1.2A Step-down High Brightness LED Driver with 5000:1 Dimming APPLICATION NOTES Setting nominal average output current with external resistor RS The nominal average output current in the LED(s) is determined by the value of the external current sense resistor (RS) connected between VIN and CSN and is given by: I OUT  0.1 / Rs ( Rs  0.082) This equation is valid when DIM pin is float or applied with a voltage higher than 2.5V (must be less than 5V). Actually, RS sets the maximum average current which can be adjusted to a less one by dimming. cycle PWM can be applied to the DIM pin, as shown below, to adjust the output current to a value below the nominal average value set by resistor RS: I OUT  0.1  D Rs (0  D  100%,2.5V  V pulse  5V ) I OUT  V pulse  0.1  D 2.5  Rs (0  D  100%,0.5V  V pulse  2.5V ) Output current adjustment by external DC control voltage The DIM pin can be driven by an external dc voltage (VDIM), as shown, to adjust the output current to a value below the nominal average value defined by RS. RS VIN 0.13Ω LED 3W L 68uH D RS VIN 0.13Ω LED 3W VIN L 68uH D DIM CSN SW PT4115 GND VIN DIM CSN SW PT4115 GND The average output current is given by: I OUT  0.1  VDIM (0.5V  VDIM  2.5V ) 2.5  Rs Note that 100% brightness setting corresponds to: (2.5V  VDIM  5V ) Output current adjustment by PWM control A Pulse Width Modulated (PWM) signal with duty China Resources Powtech (Shanghai) Limited PT4115_DS Rev EN_2.9 PWM dimming provides reduced brightness by modulating the LED’s forward current between 0% and 100%. The LED brightness is controlled by adjusting the relative ratios of the on time to the off time. A 25% brightness level is achieved by turning the LED on at full current for 25% of one cycle. To ensure this switching process between on and off state is invisible by human eyes, the switching frequency must be greater than 100 Hz. Above 100 Hz, the human eyes average the on and off times, seeing only an effective brightness that is proportional to the LED’s on-time duty cycle. The advantage of PWM dimming is that the forward current is always constant, therefore the LED color does not vary with brightness as it does with analog dimming. Pulsing the current provides precise brightness control while preserving the color purity. The dimming frequency of PT4115 can be as high as 20 kHz. WWW.CRPOWTECH.COM Page 11 PT4115 30V, 1.2A Step-down High Brightness LED Driver with 5000:1 Dimming Shutdown mode Taking the DIM pin to a voltage below 0.3V will turn off the output and the supply current will fall to a low standby level of 95μA nominal. Soft-start An external capacitor from the DIM pin to ground will provide additional soft-start delay, by increasing the time taken for the voltage on this pin to rise to the turn-on threshold and by slowing down the rate of rise of the control voltage at the input of the comparator. Adding capacitance increases this delay by approximately 0.8ms/nF. Inherent open-circuit LED protection If the connection to the LED(s) is open-circuited, the coil is isolated from the SW pin of the chip, so the device and LED will not be damaged. lower efficiency. Higher values of inductance also result in a smaller change in output current over the supply voltage range. (See graphs). The inductor should be mounted as close to the device as possible with low resistance connections to the SW and VIN pins. The chosen coil should have a saturation current higher than the peak output current and a continuous current rating above the required mean output current. Following table gives the guideline on inductor selection: Load current Inductor Saturation current Iout>1A 27-47uH 0.8A