IS31LT3360 AIC DEMO BOARD GUIDE DESCRIPTION RECOMMENDED EQUIPMENT The IS31LT3360 is a continuous mode inductive step-down converter, designed for driving a single LED or multiple series connected LEDs efficiently from a voltage source higher than the LED voltage. The chip operates from an input supply between 6V and 40V and provides an externally adjustable output current of up to 1.2A. The IS31LT3360 includes an integrated output switch and a high-side output current sensing circuit, which uses an external resistor to set the nominal average output current. Output current can be adjusted linearly by applying an external control signal to the ADJ pin. The ADJ pin will accept either a DC voltage or a PWM waveform. This will provide either a continuous or a gated output current. Applying a voltage of 0.2V or lower to the ADJ pin turns the output off and switches the chip into a low current standby state. The chip is assembled in SOT89-5 package. IS31LT3360 AIC DEMO board is used in RGB lamp or the general LED lamp. 40VDC or 12~24VAC power supply 3 pcs of LED panel (1W LED, 9 LEDs in series on each panel) Multi-meter RECOMMENDED INPUT AND OUTPUT RATINGS Input: 6~40VDC or 12~24VAC Output: 1~9 LEDs in series/667mA Note: The input voltage must be 5V higher than the output voltage (total VREF). ABSOLUTE MAXIMUM RATINGS Input voltage ≤ 40VDC or 28VAC Caution: Do not exceed the conditions listed above, otherwise the board will be damaged. PROCEDURE The IS31LT3360 DEMO Board is fully assembled and tested. Follow the steps listed below to verify board operation. Caution: Do not turn on the power supply until all connections are completed. FEATURES Simple low parts count Internal 40V power switch Wide input voltage range: 6V to 40V Up to 1.2A output current High efficiency (up to 98% ) Typical 1200:1 dimming rate Typical 3% output current accuracy Single pin on/off and brightness control using DC voltage or PWM Up to 1MHz switching frequency Inherent open-circuit LED protection Thermal shutdown protection circuitry 1) 2) 3) 4) Connect the terminals of the power supply to the AC1 and AC2 pin(If the board don’t have the rectifier(D1-D4), Connect the positive terminal of the power supply to the DC+ of the board and the negative terminal of power supply to the DC- of the board) . Connect the negative of the one of LED panel (LED arrays) to the LED1- terminal. And connect the positive of the same LED panel (LED arrays) to the LED1+ terminal. Connect the other two LED panels to LED2 and LED3 as above. Turn on the power supply and the LED panel (LED arrays) will be light. QUICK START Figure 1: Photo of IS31LT3360 Evaluation Board Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 08/31/2015 1 IS31LT3360 AIC DEMO BOARD GUIDE ORDER INFORMATION Part No. Temperature Range Package IS31LT3360-SDLS3-EBAIC IS31LT3360-SDLS4-EBAIC -40°C to +105°C (Industrial) -40°C to +125°C (Industrial) SOT89-5, Lead-free For pricing, delivery, and ordering information, please contacts ISSI’s analog marketing team at [email protected] or (408) 969-6600. DETAILED DESCRIPTION LED Current Control 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 ISENSE and in is given by: IOUT nom = 0.1/R S [for R S>0.082Ω] The table below gives values of nominal average output current for several preferred values of current setting resistor (RS) in the typical application circuit shown on Page 1: RS (Ω) Nominal Average Output Current (mA) 0.082 1200 0.1 1000 0.15 0.3 667 333 VSENSE is divided into two range to improve current accuracy, please refer to bin information on Page 2. The above values assume that the ADJ pin is floating and at a nominal voltage of VREF =1.2V. Note that RS=0.082Ω is the minimum allowed value of sense resistor under these conditions to maintain switch current below the specified maximum value. It is possible to use different values of RS if the ADJ pin is driven from an external voltage. Inductor Selection Recommended inductor values are in the range 47μH to 220μH. Higher values of inductance are recommended at higher supply voltages and low output current in order to minimize errors due to switching delays, which result in increased ripple and lower efficiency. Higher Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 08/31/2015 values of inductance also result in a smaller change in output current over the supply voltage range. The inductor should be mounted as close to LX pin as possible with low resistance connections to LX and VIN pins. PCB Layout Consideration Decoupling Capacitors and Coil It is particularly important to mount the coil and the input decoupling capacitor close to the chip to minimize parasitic resistance and inductance, which will degrade efficiency. The input decoupling capacitor (0.1μF fixed) must be placed as close to the VIN and GND pins as possible. It is also important to take account of any trace resistance in series with current sense resistor RS. LX Pin The LX pin of the chip is a fast switching node, so PCB traces should be kept as short as possible. To minimize ground 'bounce', the ground pin of the chip should be soldered directly to the ground plane. ADJ Pin The ADJ pin is a high impedance input, so when left floating, PCB traces to this pin should be as short as possible to reduce noise pickup. ADJ pin can also be connected to a voltage between 1.2V~5V. In this case, the internal circuit will clamp the output current at the value which is set by VADJ=1.2V. High Voltage Traces Avoid running any high voltage traces close to the ADJ pin, to reduce the risk of leakage due to board contamination. Any such leakage may raise the ADJ pin voltage and cause excessive output current. A ground ring placed around the ADJ pin will minimize changes in output current under these conditions. 2 IS31LT3360 AIC DEMO BOARD GUIDE V+ R4 D5 LEDs R5 LED2- C4 NC ADJ Isense 3 R8 0R IS31LT3360 LX R12 0.3R SS26 L2 47uH C3 100nF 1 U3 3 R9 0R IS31LT3360 C5 NC R3 0.3R ADJ LX D3 SS26 4 4 5 1 U2 GND LX C2 100nF 2 Isense 4 SS26 L1 47uH LED3D2 R2 0.3R PWM3 SS36 ADJ R11 0.3R PWM2 R7 0R PWM1 SS36 3 D10 2 D9 U1 GND C1 100nF Vin 5 VIN D1 R1 0.3R Vin 220uF/50V LEDs 6.8K Isense LED1C0 R10 0.3R R6 39V 6.8K 6.8K SS36 D6 LEDs 39V GND 39V 2 SS36 D8 V+ 5 D4 D7 V+ Vin VCC L3 47uH 1 IS31LT3360 C6 NC GND Figure 2: IS31LT3360 AIC DEMO Board Schematic BILL OF MATERIALS Name Symbol IC U1~U3 Resistor Description Qty Supplier Part No. LED driver 3 ISSI IS31LT3360 R1~R3 R10~R12 RES,0.3R,1/8W,±1%,SMD 6 Yageo RL1206FR-070R3L Resistor R4~R6 RES,6.8K,1/8W,±5%,SMD 3 Yageo RC1206JR-076K8L Resistor R7~R9 RES,0R,1/10W,±5%,SMD 3 Yageo RL0805FR-070RL Capacitor C0 CAP, 220µF,50V,±20%,IND 1 Rubycon Capacitor C1~C3 CAP,0.1µF,50V,±10%,SMD 3 Yageo CC0603KRX7R9BB104 Capacitor C4~C6 Not Installed 3 Diode D1~D3 Schottky,SS26,2A,60V SMA 3 TOSHIBA SR260 Diode D4~D6 Zener,39V,0.5W,SMD 3 ST ZMM39B Diode D7~D10 Schottky,SS36,3A,60V SMA 4 TOSHIBA SR360 Inductor L1~L3 47µH,ISAT≥1A 3 Würth Elektronik 744777147 Bill of materials refers to Figure 2 above. Note 1: C8, C9, C10 are the optional components. They can filter the noise coupling to the ADJ pin. Note 2: D4, D5, D6 are the optional components. They can protect the IC as removing the loading with the power on. Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 08/31/2015 3 IS31LT3360 AIC DEMO BOARD GUIDE 3 0 0 2 1 0 0 3 8 7 2 1 0 Figure 3: Board Component Placement Guide - Top Layer Figure 4: Board PCB Layout - Top Layer Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 08/31/2015 4 IS31LT3360 AIC DEMO BOARD GUIDE Figure 5: Board Component Placement Guide - Bottom Layer Figure 6: Board PCB Layout - Bottom Layer Note: Physical dimensions are (L × W × H): 55mm × 21mm × 22mm. Copyright © 2015 Integrated Silicon Solution, Inc. All rights reserved. ISSI reserves the right to make changes to this specification and its products at any time without notice. ISSI assumes no liability arising out of the application or use of any information, products or services described herein. Customers are advised to obtain the latest version of this device specification before relying on any published information and before placing orders for products. Integrated Silicon Solution, Inc. does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such applications unless Integrated Silicon Solution, Inc. receives written assurance to its satisfaction, that: a.) the risk of injury or damage has been minimized; b.) the user assume all such risks; and c.) potential liability of Integrated Silicon Solution, Inc is adequately protected under the circumstances Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 08/31/2015 5