NCP1422LEDGEVB NCP1422 High Current LED Driver Evaluation Board User's Manual http://onsemi.com EVAL BOARD USER’S MANUAL Description The circuit is configured to minimize power dissipation in the current sense resistor and the effects of lot-to-lot LED forward voltage (VF) variation on LED current. Application note AND8171/D describes how to design this circuit. The NCP1422 is a monolithic, micro-power, high-frequency, step-up switching converter IC designed for battery operated hand-held electronic products with up to 800 mA loading. It integrates a synchronous rectifier (Sync-Rect) to improve efficiency and to eliminate the external Schottky Diode. The NCP1422’s high switching frequency (up to 1.2 MHz) allows for a low profile, small sized inductor and output capacitor to be used. When the device is disabled, the internal conduction path from the battery to the load is fully blocked, which isolates the load from the battery. This True-Cutoff function reduces the shutdown current to typically only 50 nA. A Ring-Killer is also integrated to eliminate high-frequency ringing in discontinuous conduction mode. Finally, a Low-Battery Detector, Logic-Controlled Shutdown, Cycle-by Cycle Current Limiting and Thermal Shutdown provide value-added features for various battery operated applications. With all these functions on, the quiescent supply current is typically only 8.5 mA. This device is available in the compact and low profile DFN-10 package. The NCP1422LED evaluation board uses the NCP1422 to drive a high power, white LED. A low voltage MOSFET switch circuit on the board can be pulsed to switch between a low and high LED current as would be found in a focus and flash application. D1 SNS C2 R2 R3 FLASH ON + OFF 50 ms Pulse − Q1 R5 Features Capable of driving White LEDs up to 800 mA High Switching Frequency, up to 1.2 MHz True-Cutoff Function Reduces Device Shutdown Current to Typically 50 nA Figure 1. NCP1422LEDG Evaluation Board R1 NCP1422 1 FB VOUT 2 LBI/EN LX 3 LBO GND 4 REF BAT R6 R7 C3 Vbat 8 7 6 5 L1 C1 VIN U1 ENABLE R4 GND R8 Vbat Figure 2. NCP1422LEDG Evaluation Board Schematic Semiconductor Components Industries, LLC, 2012 September, 2012 − Rev. 1 1 Publication Order Number: EVBUM2136/D NCP1422LEDGEVB Test Procedure 9. Measure SNS voltage. It Should be between 700−900 mV 10. Disconnect Jumper from FLASH 11. Apply Function Generator Output Across FLASH+ and FLASH− 12. LED Should Alternate between Two Brightness Levels 13. Disconnect Function Generator from FLASH 14. Turn Off Power Supply and Disconnect. Reconnect Jumpers to ENABLE and FLASH Required Equipment 1. Power Supply (Capable of > 5 V, 2 A with 100 mV Resolution) 2. Voltmeter 3. Function Generator Set to Parameters in PULSE Table (see Table 1) Testing 1. Set DC Power Supply to 3.6 Vdc and Current Limit to 2 A 2. Disconnect Jumper from ENABLE 3. Connect Jumper to FLASH 4. Connect DC Power Supply to VIN and GND at Top of Board (Positive on VIN, Negative on GND) 5. LED Should be OFF 6. Connect Voltmeter between SNS and GND 7. Connect Jumper to ENABLE 8. LED Should be ON (CAUTION, DO NOT LOOK DIRECTLY AT THE LED. IT IS EXTREMELY BRIGHT) Table 1. PULSE (Note 1) Waveform Squarewave Trequency 4.0 Hz Amplitude 2.5 Vpp Offset 1.25 Vdc % Duty 20% 1. This produces a 5 V, 50 ms pulse train. Table 2. NCP1422LEDG EVALUATION BOARD BILL OF MATERIALS Designator RoHS Compliant Value U1 1 NCP1422 Boost Converter − − DFN−10 (3 3 mm) ON Semiconductor NCP1422MNR2G No Yes D1 1 Lumiled High Power White LED − − (1.64 2.04 0.9 mm) Lumiled LXCL−PWF1 No Yes Q1 1 Torch/Flash Switch − − SC−88 ON Semiconductor NTJS3157NT4G No Yes L1 1 Inductor 6.8 mH, 800 mA 20% (5.6 5.0 1.0 mm) TDK VLP5610T−6R8MR80 No Yes C1, C2 2 Ceramic Capacitor 22 mF, 6.3 V X5R 20% 0805 TDK C2012X5R0J226M Yes Yes C3 1 Ceramic Capacitor 470 nF, 6.3 V X5R 10% 0402 TDK ECJ−0EB0J474K Yes Yes Qty. Description Footprint Manufacturer Manufacturer Part Number Substitution Allowed Tolerance R1 1 Resistor 665 kW 1% 0402 Vishay CRCW0402665KFKED Yes Yes R2, R6, R7 3 Resistor 100 kW 1% 0402 Vishay CRCW0402100KFKED Yes Yes R3 1 Resistor (1.33 W)* 2.67 W 1% 1206 Vishay CRCW12062R67FKED Yes Yes R4 1 Resistor 6.65 W 1% 1206 Vishay CRCW12066R65FKED Yes Yes R5 1 Resistor 1.0 kW Any 0402 Vishay CRCW04021K00FKED Yes Yes R8 1 Resistor 10 kW Any 0402 Vishay CRCW040210K0FKED Yes Yes GND 1 Ground Shunt − − − Harwin D3082−05 Yes Yes VIN, GND 2 Post, 3 position, 0.1” spacing − − − Molex 90120−0160 Yes Yes FLASH, SNS, ENABLE 3 Post, 2 position, 0.1” spacing − − − Molex 90120−0161 Yes Yes *2−2.67 W resistors were used in parallel http://onsemi.com 2 NCP1422LEDGEVB ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC owns the rights to a number of patents, trademarks, copyrights, trade secrets, and other intellectual property. A listing of SCILLC’s product/patent coverage may be accessed at www.onsemi.com/site/pdf/Patent−Marking.pdf. SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. “Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC does not convey any license under its patent rights nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner. PUBLICATION ORDERING INFORMATION LITERATURE FULFILLMENT: Literature Distribution Center for ON Semiconductor P.O. Box 5163, Denver, Colorado 80217 USA Phone: 303−675−2175 or 800−344−3860 Toll Free USA/Canada Fax: 303−675−2176 or 800−344−3867 Toll Free USA/Canada Email: [email protected] N. American Technical Support: 800−282−9855 Toll Free USA/Canada Europe, Middle East and Africa Technical Support: Phone: 421 33 790 2910 Japan Customer Focus Center Phone: 81−3−5817−1050 http://onsemi.com 3 ON Semiconductor Website: www.onsemi.com Order Literature: http://www.onsemi.com/orderlit For additional information, please contact your local Sales Representative EVBUM2136/D