IS31LT3360 3CH DEMO BOARD GUIDE DESCRIPTION RECOMMENDED EQUIPMENT The IS31LT3360 is a continuous mode inductive 40VDC power supply step-down converter, designed for driving a single LED 3 pcs of LED panel (3 WLEDs, 10 LEDs in series or multiple series connected LEDs efficiently from a on each panel) voltage source higher than the LED voltage. The chip Multi-meter operates from an input supply between 6V and 40V and provides an externally adjustable output current of up to 1.2A. RECOMMENDED INPUT AND OUTPUT RATINGS The IS31LT3360 includes an integrated output switch Input: 6~40VDC and a high-side output current sensing circuit, which Output: 1~10 LEDs in series/667mA uses an external resistor to set the nominal average Note: The input voltage must be 2V higher than the output output current. voltage (total V ). F Output current can be adjusted linearly by applying an external control signal to the ADJ pin. The ADJ pin will ABSOLUTE MAXIMUM RATINGS accept either a DC voltage or a PWM waveform. This will provide either a continuous or a gated output Input voltage 40VDC current. Caution: Do not exceed the conditions listed above, otherwise Applying a voltage of 0.2V or lower to the ADJ pin the board will be damaged. turns the output off and switches the chip into a low current standby state. PROCEDURE The chip is assembled in SOT89-5 package. The IS31LT3360 DEMO Board is fully assembled and IS31LT3360 3CH DEMO board is used in RGB lamp or tested. Follow the steps listed below to verify board the general LED lamp. operation. Caution: Do not turn on the power supply until all connections FEATURES are completed. Simple low parts count 1) Connect the terminals of the power supply to the Internal 40V power switch AC1 and AC2 pin(If the board dont have the rectifier(D1-D4), Connect the positive terminal of Wide input voltage range: 6V to 40V the power supply to the VCC of the board and the Up to 1.2A output current negative terminal of power supply to the GND of High efficiency (up to 98% ) the board) . Typical 1200:1 dimming rate 2) Connect the negative of the one of LED panel Typical 3% output current accuracy (LED arrays) to the LED1- terminal. And connect Single pin on/off and brightness control using DC the positive of the same LED panel (LED arrays) voltage or PWM to the LED1+ terminal. Up to 1MHz switching frequency 3) Connect the other two LED panels to LED2 and Inherent open-circuit LED protection LED3 as above. Thermal shutdown protection circuitry 4) Turn on the power supply and the LED panels (LED arrays) will be light. QUICK START Figure 1: Photo of IS31LT3360-3CH Evaluation Board Lumissil Microsystems www.lumissil.com 1 Rev. B, 04/27/2016 IS31LT3360 3CH DEMO BOARD GUIDE ORDER INFORMATION Part No. Temperature Range Package IS31LT3360-SDLS3-EB3CH -40C to +105C (Industrial) SOT89-5, Lead-free IS31LT3360-SDLS4-EB3CH -40C to +125C (Industrial) For pricing, delivery, and ordering information, please contacts Lumissils analog marketing team at analog Lumissil.com or (408) 969-6600. DETAILED DESCRIPTION output current over the supply voltage range. The inductor should be mounted as close to LX pin as LED Current Control possible with low resistance connections to LX and V IN pins. The nominal average output current in the LED(s) is determined by the value of the external current sense resistor (R ) connected between V and I and in S IN SENSE PCB LAYOUT CONSIDERATION is given by: I = 0.1/Rs for Rs>0.082 Decoupling Capacitors And Coil OUT NOM The table below gives values of nominal average It is particularly important to mount the coil and the output current for several preferred values of current input decoupling capacitor close to the chip to setting resistor (Rs) in the typical application circuit minimize parasitic resistance and inductance, which shown on Page 1: will degrade efficiency. The input decoupling capacitor (0.1F fixed) must be placed as close to the V and IN Nominal Average Output GND pins as possible. It is also important to take R ( ) S Current (mA) account of any trace resistance in series with current sense resistor R . S 0.082 1200 LX Pin 0.1 1000 The LX pin of the chip is a fast switching node, so PCB 0.15 667 traces should be kept as short as possible. To 0.3 333 minimize ground bounce , the ground pin of the chip V is divided into two ranges to improve current should be soldered directly to the ground plane. SENSE accuracy, please refer to bin information on Page 3. ADJ Pin The above values assume that the ADJ pin is floating The ADJ pin is a high impedance input, so when left and at a nominal voltage of V =1.2V. REF floating, PCB traces to this pin should be as short as Note that R =0.082 is the minimum allowed value of possible to reduce noise pickup. ADJ pin can also be S sense resistor under these conditions to maintain connected to a voltage between 1.2V~5V. In this case, switch current below the specified maximum value. the internal circuit will clamp the output current at the value which is set by V =1.2V. ADJ It is possible to use different values of R if the ADJ pin S is driven from an external voltage. High Voltage Traces Inductor selection Avoid running any high voltage traces close to the ADJ pin, to reduce the risk of leakage due to board Recommended inductor values are in the range 47 H contamination. Any such leakage may raise the ADJ to 220 H. pin voltage and cause excessive output current. A ground ring placed around the ADJ pin will minimize Higher values of inductance are recommended at higher supply voltages and low output current in order changes in output current under these conditions. to minimize errors due to switching delays, which result in increased ripple and lower efficiency. Higher values of inductance also result in a smaller change in Lumissil Microsystems www.lumissil.com 2 Rev. B, 04/27/2016