VP3162STG5

VP3162 1A/40V/1.2MHz White LED Driver General Description Features The VP3162 is designed to drive up to 10 white - Wide Input Voltage from 2.75V to 6V LEDs in series with a 3.6V cell Li-Ion battery. It - 300mV Feed-Back Voltage works as a boost converter using current mode, - 40V Open Load Protection 1.2MHz PWM frequency with the measure of an - DC Voltage/PWM Dimming Control external current sense resistor to regulate the LED - 1A Maximum Input Current current. In order to minimize the power loss and - Integrated 400mΩ MOSFET Switch keep the efficiency, the feedback voltage is de- - 1.2MHz Switching Frequency signed as low as 300mV. With the DC voltage - 2.75V UVLO Protection dimming control, it is easily to adjust the bright- - 1µA Low Shutdown Current ness of LEDs in either analog method or PWM duty - Over Temperature Protection control. - SOT23-5 Package with RoHS 2.0 Compliant The VP3162 features many protection schemes such as UVLO, open load protection, 1A current limit and over-temperature protection. VP3162 is packaged with the popular SOT23-5 small package with RoHS 2.0 compliant, green package is optional. Applications - LCD Panel - MID/PND/GPS - Digital Still Camera/Photo Frame - Smart Phone Typical Application VP3162 Rev A.00 1 http://www.viva-elec.com.tw VP3162 Functional Block Diagram Pin Assignments And Descriptions Pin No. Pin I/O/P 1 LX O 2 GND P Function Description Switch Output. Connect this pin to the node between the inductor and the schottky diode. Power Ground. Feedback Input. FB monitors the feedback voltage to regulate the LED 3 FB I current. Connect a current sense resistor from the bottom of the LED string to ground to configure LED current. 4 EN I 5 IN P VP3162 Rev A.00 Chip Enable. Pull EN high to enable the regulator, pull it low to turn it off. Pull up with a 100kΩ resistor to start it up automatically. Power Input. Drive IN pin with a 2.75V to 6V power source to activate the LED driver. 2 http://www.viva-elec.com.tw VP3162 Absolutely Maximum Ratings Over operating free-air temperature range, unless otherwise specified (* 1) Symbol Parameter Limit Unit VIN Supply voltage range -0.3 to 6.5 V VLX Switch voltage range -0.3 to 42 V VIN(EN, FB) Low voltage input range -0.3 to 6.5 TJ Operating junction temperature range -40 to +160 o TSTG Storage temperature range -65 to 150 o Electrostatic discharge Human body model ±2 Electrostatic discharge Machine model ±200 θJC Thermal Resistance (Junction to Case) 110 o θJA Thermal Resistance (Junction to Air) 220 o V C C kV V C/W C/W ( *1): Stress beyond those listed at “absolute maximum rating” table may cause permanent damage to the device. These are stress rating ONLY. For functional operation are strongly recommend follow up “recommended operation conditions” table. Recommended Operating Conditions Symbol Parameter VIN Specification Unit Min Max Supply voltage 2.75 6 TA Operating free-air temperature range -40 85 o TJ Operating Junction range -40 125 o VP3162 Rev A.00 3 V C C http://www.viva-elec.com.tw VP3162 Electrical Characteristics TA = 25℃, VIN = 3.6V, unless otherwise noted Specification Symbol Parameter Test Condition ISD Shutdown supply current IQ Quiescent current VUVLO Under voltage lockout 2.65 V VUVLOHYS UVLO hystersis 100 mV VFB Feedback voltage VEN=2V IFB Feedback bias current VFB=0.1V RDS(ON) Internal switch RDS(ON) (*1) 0.4 Ω Current limit 1 A 42 V Min Unit Typ Max VEN=0V 1 5 µA VEN=3.6V, VFB=0.15V 0.9 2 mA 270 VOVP rising 300 330 mV 0.05 1 µA VOVP Load open protection threshold fOSC Oscillation frequency DMAX Maximum duty cycle VFB=0V 90 % Chip enable threshold VEN rising 1 V Chip shutdown threshold VEN falling 0.4 V 1 1.2 1.4 MHz Thermal shutdown threshold(*1) 160 o C Thermal shutdown hysteresis(*1) 20 o C (*1) Design Center Value VP3162 Rev A.00 4 http://www.viva-elec.com.tw VP3162 Functional Descriptions The VP3162 is a compact high-efficiency boost by setting the external current sense resistor in converter with integrated switch specifically de- series with the LED string. It can be calculated by signed to drive up to 10 WLEDs in series. Series the following formula: connection of the LEDs provides identical LED current resulting in uniform brightness. Fixed 1.2MHz operation allows possible smallest output ripple where ILED is the output current of LEDs, VFB is the and external component size. With high con- feedback reference voltage, RISET is the current version efficiency and small package, the VP3162 is sense resistor. Hence the offset of LED output ideally suitable for portable devices where PCB area current depends on the accuracy of VREF and RISET. is especially concerned. Soft Start The VP3162 limits the inrush current at start-up by increasing the current limit. This prevents unwanted shutdown otherwise may be triggered Figure 1. Setting LED current by voltage drop due to large inrush current. Chip Enable Under Voltage Lock-Out Protection Pull the EN pin higher than 1V to enable the de- Once the VIN becomes too low, the internal gate vice and initiate its soft start cycle. Pulling the EN driver may not work well. The VP3162 internal cir- pin lower than 0.4V disables the device and re- cuit will remain disabled until VIN exceeds the input duces it shutdown current to less than 1µA typi- UVLO threshold voltage. This function assures the cally. Never let the EN pin floating as it will result boost converter works properly and protects the the driver in unknown state. internal gate driver away from entering any unexpected state. Dimming Control Open LED Protection 1. PWM Dimming: During each switching cycle, the VP3162 monitors the voltage at the LX pin. Once the LX voltage exceeds the OVP threshold voltage, the converter will turn off the switch and enter shutdown mode. Toggling EN pin from logic low to logic high will resume the fault state. LED Current Setting Figure 2. PWM dimming control The simplest way to perform LED brightness The LED current is constant and can be adjusted VP3162 Rev A.00 control is to connect an external PWM waveform 5 http://www.viva-elec.com.tw VP3162 Functional Descriptions (cont.) at EN pin. During 0% duty of PWM waveform the VP3162 will be turned off and it will be turned on when the duty of PWM waveform is back to 100%. Since the brightness of LED is proportionally to its driving current and the average LED current is proportionally with the PWM duty where VDIM_MAX is the upper bound of VDIM, cycle, the LED brightness can be controlled ILED_DIMMED_MIN is the minimal value of LED current easily. when VDIM is equal to VDIM_MAX, ILED_UNDIMMED is the maximum ILED current when VDIM is equal to VFB. Figure 2 shows the circuit of PWM dimming to control the brightness of LEDs. The appropriate 3. Filtered PWM Dimming from FB pin: PWM frequency range is about 100Hz~50kHz. 2. Analog Dimming: Figure 4. Dimming with filtered PWM waveform Figure 4 shows the other way to control the LED Figure 3. Dimming with a DC voltage brightness by varying PWM duty. The calaculation of LED current is: Figure 3 shows the circuit of analog dimming control with a external DC voltage. As the VDIM increases, the voltage drop on R2 increases and the LED current decreases. One thing very im- where Duty is the duty of the PWM waveform. portant is the dimming current must be much larger than the FB bias current and much smaller This configuration is recommended if the fre- than the LED current. In this configuration, the quency of PWM controlling waveform is larger LED current can be calculated as: then 100kHz. Over Temperature Protection The VDIM shall be larger than VFB, or the inverse The excessive internal dissipation of thermal case will happen and the brightness of LEDs will protection will damage VP3162. The junction over increase. -temperature threshold is 160ºC. The output voltage resumes automatically when the temper- The analog dimming circuit network can be de- ature reduces more than the temperature hyste- scribed by different resistor value by the fol- resis 20ºC. lowing equation: VP3162 Rev A.00 6 http://www.viva-elec.com.tw VP3162 Application Information 3. Keep the main current traces as possible as Components Selection short and wide. External component selection begins with induc- 4. LX node of DC/DC converter is with high fre- tor value selection based on the considerations of quency voltage swing. It should be kept at a the output voltage, output current, and the maxi- small area. mum/minimum input voltages. Catch diode and 5. Place the feedback components as close as input/output capacitors can be selected according possible to the IC and keep away from the to the inductor value L. noisy devices. Inductor Selection Inductor selection should consider the inductor value, rated current, DC resistance, size, core material and cost. The inductor value is selected based on the consideration of inductor ripple current. The recommended value of inductor for 10 WLEDs applications is from 3.3µH to 4.7µH. The inductor should have low core loss at 1.2MHz and lower DC resistance for better efficiency. The inductor saturation current rating should be considered to cover the inductor peak current. Diode Selection Figure 5. VP3162 layout recommendation The catch diode should be capable of handling the output voltage and the peak switch current. Make sure that the diode peak current rating is at least ILX(PEAK) and that its breakdown voltage exceeds VOUT. Schottky diodes are recommended due to its low forward voltage and low reverse recovery current. The capability for handling power dissipation should be considered. Layout Consideration 1. Input and output capacitors should be placed close to the IC and connected to ground plane to reduce noise coupling. 2. The GND should be connected to a strong ground plane for heat sinking and noise protection. VP3162 Rev A.00 7 http://www.viva-elec.com.tw VP3162 Typical Characteristics TA = 25℃, VIN = 3.6V, unless otherwise noted Figure 6. Efficient vs. Supply Voltage Figure 7. Quiescent Current vs. Supply Voltage VIN=3.6V, LED=1p10s, ILED=20mA, L=4.7µH VLX:10V/div Time base: 400ns/div Figure 8. Frequency vs. Supply Voltage Figure 9. Switching Waveform VIN=3.6V, LED=1p10s, ILED=20mA, L=4.7µH VIN=3.6V, LED=1p10s, ILED=20mA, L=4.7µH VEN:5V/div VEN:5V/div VOUT :10V/div VOUT :10V/div VLX:10V/div VLX:10V/div Time base: 400ms/div Time base: 50ms/div Figure 10. Soft-Start Waveform VP3162 Rev A.00 Figure 11. Shutdown Waveform 8 http://www.viva-elec.com.tw VP3162 Typical Application Circuits Figure 12. Typical Application with Driving 1p10s WLEDs Figure 13. Typical Application with Driving 2p8s WLEDs VP3162 Rev A.00 9 http://www.viva-elec.com.tw VP3162 Package Information SOT23-5 Notes: 1.Package Outline Unit Description: BSC: Basic. Represents theoretical exact dimension or dimension target. MIN: Minimum dimension specified. MAX: Maximum dimension specified. REF: Reference. Represents dimension for reference use only. This value is not a device specification. TYP: Typical. Provided as a general value. This value is not a device specification. 2.Dimensions in Millimeters. VP3162 Rev A.00 10 http://www.viva-elec.com.tw VP3162 Ordering Information VP3162 5: Pin Count G: Green & RoHS Compliant ST: SOT-23 Part No. Q`ty/Reel VP3162STG5 3,000 Contact Information Viva Electronics Incorporated 10F-1, No. 32, Gaotie 2nd Rd., Zhubei City, Hsinchu County, Taiwan, R.O.C. Tel: 886-3-6579508 Fax: 886-3-6579509 WWW: http://www.viva-elec.com.tw Sales: sales@viva-elec.com.tw FAE Support: fae@viva-elec.com.tw IMPORTANT NOTICE Viva Electronics Incorporated reserves the right to make changes without further notice to any products or specifications herein. Viva Electronics Incorporated does not assume any responsibility for use of any its products for any particular purpose, nor does Viva Electronics Incorporated assume any liability arising out of the application or use of any its products or circuits. Viva Electronics Incorporated does not convey any license under its patent rights or other rights nor the rights of others. VP3162 Rev A.00 11 http://www.viva-elec.com.tw