Designed and produced by Diodes Zetex Applications team, Oldham, UK ZXLD1370EV3 EVALUATION BOARD USER GUIDE 9 AMP HIGH CURRENT BUCK LED DRIVER APPLICATION Fig. 1 ZXLD1370EV3 Evaluation board connection diagram Issue 1 – February 2011 © Diodes Incorporated, 2011 www.diodes.com ZXLD1370EV3 Fig. 2 ZXLD1370EV3 Schematic Diagram PARTS LIST Ref Value U1 LED Driver Controller Q1 30V Nch 20A MOSFET Q2 NOT FITTED D1 Freewheeling diode 20A X2 45V L1 4.7uH 15A C1 C2 C3 C4 C11 C12 C13 C5 C6 C7 C8 C9 C10 R1 R2 R3 R8 R7 R9 R4 R5 R6 R12 R13 HS1 Package TSSOP16L - EP DPAK Part Number ZXLD1370 Manufacturer Diodes Contact Details www.diodes.com DMN3020LK3 Diodes www.diodes.com TO220 MBR2045CTP Diodes www.diodes.com Bourns Wurth 100pF 50V X7R 4.7uF 25V X7R 10uF 25V X7R NOT FITTED 0805 SRP1270-4R7M 7443551470 Generic www.bourns.com www.we-online.com www.murata.com GRM31CR71E475K A88L GCM32ER71E106K A57L Murata www.murata.com Murata www.murata.com 10nF 50V X7R 0R05 1% 0805 Generic 4527 0R 47K 1% 33R 1% NOT FITTED 0805 0805 0805 1206 WSR3R0500FEA WSR2R0500FEA Generic Generic Generic 5R6 1% Heatsnk for D1 0805 1206 1210 www.murata.com Generic 6396BG Vishay Vishay www.vishay.com www.vishay.com AVVID Thermalloy Issue 1 – February 2011 www.diodes.com © Diodes Incorporated 2011 2 ZXLD1370EV3 NOTES The PCB is supplied with R3 and R8 0R0 resistors fitted. The ‘ADJ’ pin and the ‘TADJ’ pin are disabled. The LED current of the ZXLD1370EV3 boards = 9A with 2x // 0R05 = 0R025 (R1 & R2) For other reference designs or more applications information, please see the ZXLD1370 datasheet. DESCRIPTION ZXLD1370EV3 is designed for LED Lighting applications which require a very high LED current such as LED projectors, entertainment lighting, emergency vehicle lighting etc. The LED current of this evaluation board is set at 9A with the input voltage ranging from 10V up to 18V. OPERATION In buck mode, the LED current is sensed by the resistor (R1 // R2). The ‘GI’ output drives the input of a comparator, and the ‘ADJ’. ‘GATE’ drives the gate of the external NMOS switch transistor through the chip. When the NMOS switch is on, current flows from ‘VIN’, through (R1 // R2), the LED, the inductor and the switch to ground, and increases until a high value is reached. Then, ‘GATE’ goes low, the switch turns off and the current flows through (R1 // R2), the LED, the inductor and D1, back to ‘VIN’. When the inductor current has gone low, ‘GATE’ goes high, the switch turns on, and the cycle repeats. The circuit oscillates. The average current in the LED equals the average of the maximum and minimum threshold currents. The ripple current (hysteresis) is equal to the difference between the thresholds. The control loop keeps the average LED current at the level set by the voltage on the ‘ADJ’ pin. Loop compensation is achieved by C1. Issue 1 – February 2011 www.diodes.com © Diodes Incorporated 2011 3 ZXLD1370EV3 Fig. 3 Waveforms Issue 1 – February 2011 www.diodes.com © Diodes Incorporated 2011 4 ZXLD1370EV3 ADJ Terminal (DC output current adjustment) On the ZXLD1370EV3, R3 connects the ‘ADJ’ pin to ‘VREF’ to give 100% LED current. The ‘ADJ’ pin can be driven with an external DC voltage >=125mV and <=2.5V to adjust the LED current to >=10% and <=200% of the nominal value. To do this, remove R3, fit R5 and apply an external DC voltage between ‘ADJIN’ and ‘GND’. The voltage ‘VADJ ‘ can be derived from a resistor-divider connected between ‘REF’ and ‘GND’. ‘ADJ’ has a high impedance within its normal operating voltage range. An internal 2.6V clamp protects the device against high input voltages and limits the maximum output current to about 4% above the maximum current set by ‘VADJ ‘ if the maximum input voltage is exceeded. PWM Terminal (PWM output current control/dimming) The LED current can be adjusted digitally, by applying a low frequency PWM logic signal to the ‘PWM’ pin to turn the controller on and off. This will produce an average output current proportional to the duty cycle of the control signal. During PWM operation, the device remains powered-up and only the output is switched by the control signal. The device can be shut down by taking the ‘PWM’ pin to to <0.4V with a short to 0V or via a suitable open collector NPN, or open drain NMOS transistor, for >15ms. In shutdown, most of the circuitry inside the device is off and the quiescent current will be typically 90µA. TADJ Terminal (Thermal control of LED current) The Thermal control circuit monitors the voltage on the ‘TADJ’ pin and reduces the output current linearly if the voltage on ‘TADJ’ < 625mV. An NTC thermistor and resistor can be connected to set the voltage on the ‘TADJ’ pin = 625mV at the required threshold temperature. This will give 100% LED current below the threshold temperature and <100% current above it as shown in the graph. The temperature threshold can be changed by adjusting the value of Rth and/or the thermistor to suit the LED used. On the ZXLD1370EV3, Rth is 1K3 (R4). To use Thermal control, remove R8, fit R6, and fit a 10K NTC (Negative Temperature Coefficient) type thermistor between ‘TADJ’ and ‘GND’. This will set the threshold temperature to ~90ºC. Thermal control by LED current reduction Fig. 4 Thermal control The Thermal Control feature can be disabled by connecting ‘TADJ’ to ‘REF’ through the jumper resistor R8. Issue 1 – February 2011 www.diodes.com © Diodes Incorporated 2011 5 ZXLD1370EV3 BOARD LAYOUT Issue 1 – February 2011 www.diodes.com © Diodes Incorporated 2011 6 ZXLD1370EV3 INTENTIONALLY BLANK Issue 1 – February 2011 www.diodes.com © Diodes Incorporated 2011 7 ZXLD1370EV3 IMPORTANT NOTICE DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARD TO THIS DOCUMENT, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION). Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes without further notice to this document and any product described herein. Diodes Incorporated does not assume any liability arising out of the application or use of this document or any product described herein; neither does Diodes Incorporated convey any license under its patent or trademark rights, nor the rights of others. Any Customer or user of this document or products described herein in such applications shall assume all risks of such use and will agree to hold Diodes Incorporated and all the companies whose products are represented on Diodes Incorporated website, harmless against all damages. Diodes Incorporated does not warrant or accept any liability whatsoever in respect of any products purchased through unauthorized sales channels. Should Customers purchase or use Diodes Incorporated products for any unintended or unauthorized application, Customers shall indemnify and hold Diodes Incorporated and its representatives harmless against all claims, damages, expenses, and attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized application. Products described herein may be covered by one or more United States, international or foreign patents pending. Product names and markings noted herein may also be covered by one or more United States, international or foreign trademarks. LIFE SUPPORT Diodes Incorporated products are specifically not authorized for use as critical components in life support devices or systems without the express written approval of the Chief Executive Officer of Diodes Incorporated. As used herein: A. Life support devices or systems are devices or systems which: 1. are intended to implant into the body, or 2. support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in significant injury to the user. B. A critical component is any component in a life support device or system whose failure to perform can be reasonably be expected to cause the failure of the life support device or to affect its safety or effectiveness. Customers represent that they have all necessary expertise in the safety and regulatory ramifications of their life support devices or systems, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products and any use of Diodes Incorporated products in such safety-critical, life support devices or systems, notwithstanding any devices- or systems-related information or support that may be provided by Diodes Incorporated. Further, Customers must fully indemnify Diodes Incorporated and its representatives against any damages arising out of the use of Diodes Incorporated products in such safety-critical, life support devices or systems. Copyright © 2009, Diodes Incorporated www.diodes.com Sales offices The Americas Europe Taiwan Shanghai Shenzhen Korea 3050 E. Hillcrest Drive Westlake Village, CA 91362-3154 Tel: (+1) 805 446 4800 Fax: (+1) 805 446 4850 Kustermannpark Balanstraße 59, D-81541 München Germany Tel: (+49) 894 549 490 Fax: (+49) 894 549 4949 7F, No. 50, Min Chuan Road Hsin-Tien Taipei, Taiwan Tel: (+886) 289 146 000 Fax: (+886) 289 146 639 Rm. 606, No.1158 Changning Road Shanghai, China Tel: (+86) 215 241 4882 Fax (+86) 215 241 4891 Room A1103-04, ANLIAN Plaza, #4018 Jintian Road Futian CBD, Shenzhen, China Tel: (+86) 755 882 849 88 6 Floor, Changhwa B/D, 1005-5 Yeongtong-dong, Yeongtong-gu, Suwon-si, Gyeonggi-do, Korea 443-813 Tel: (+82) 312 731 884 Fax: (+82) 312 731 885 Fax: (+86) 755 882 849 99 Issue 1 – February 2011 www.diodes.com © Diodes Incorporated 2011 8