User Guide for ANALOG DEVICES models including: DC1019A Radio Magic, DC1019A, Radio Magic, Magic
DC1019A Analog Devices - РКС Компоненти - РАДІОМАГ
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DocumentDocumentQUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1019A DUAL WHITE LED DRIVER CONVERTER LT3497EDDB DESCRIPTION WARNING! Do not look directly at operating LED. This circuit produces light that can damage eyes. Demonstration circuit 1019A is a Dual White LED Driver Converter featuring the LT®3497 in a 3mm x 2mm DFN package. The demo circuit demonstrates small size and low component count in two independent Boost Circuits. It drives two independent LED strings at 20mA from a 3V-10V input. Other features of the LT3497, such as the internal schottky diodes, the high switching frequency and the internal open circuit protection, allow the use of tiny components. Different dimming controls can be implemented on the demo board. Optional N-MOSFET placeholders are provided to test direct PWM dim- ming. Analog dimming is done via the SHDN/DIMMING CONTROL terminals. Please refer to the quick start procedure. The high side current sensing feature of the LT3497 allows "one wire" current source, i.e. the low side of the LED string can return to ground anywhere. The LT3497 datasheet gives complete description of the part, operation and application information. The datasheet must be read in conjunction with this quick start guide for working on or modifying the demo circuit 1019A. Design files for this circuit board are available. Call the LTC factory. LTC, LT is a registered trademark of Linear Technology Corporation Table 1. Performance Summary (TA = 25°C) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VIN Input Supply Range ** IOUT Output Current 3 10 V 19 20 21 mA VOUT VOPEN IQ Output Voltage Efficiency CAP pin Over voltage Protection Quiescent Current VIN=3.6V LED Open VIN = 4.2V, CTRL=ON, LEDs open 19.5 V 72.3 % 30 32 34 V 15 mA IQSHDN Fs Quiescent Current in Shutdown Switching Frequency VIN = 4.2V, CTRL=OFF 10 µA 1.8 2.3 2.8 MHz ** The Input Supply Range of the Demo Circuit 1019A is limited by Maximum Input Voltage of the LT3497. Always ensure that this level is not exceeded. 1 Downloaded from Arrow.com. QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1019A DUAL WHITE LED DRIVER CONVERTER QUICK START PROCEDURE Demonstration circuit 1019A is easy to set up to evaluate the performance of the LT3497. Refer to Figure 1 for proper measurement equipment setup and follow the procedure below: Note: when measuring the input or output voltage ripple, care must be taken to avoid a long ground lead on the oscilloscope probe. Measure the input or output voltage ripple by touching the probe tip directly across the Vin or Vout and GND terminals. See Figure 2 for proper scope probe technique. 1. Place jumpers in the following positions to test the circuit: JP1 ON JP2 ON 2. With power off, connect the input power supply to VIN and GND. 3. Turn on the power at the input. Note: Make sure that the input voltage does not exceed 10V. 4. Check for the proper voltages and currents. Note: If the LEDs do not light up, check the jumper settings. 5. Once the proper operations are established, adjust the input within the operating range and observe the parameters of interest. 6. To test the filtered PWM dimming or the direct DC dimming, remove the jumper JP1 or JP2, apply the PWM or the DC signal to the SHDN/DIMMING CTRL1 or SHDN/DIMMING CTRL2 and observe the brightness of the LED output. 7. To test the direct PWM dimming, follow the Direct PWM Dimming section in the datasheet. Figure 1. Proper Measurement Equipment Setup 2 Downloaded from Arrow.com. QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1019A DUAL WHITE LED DRIVER CONVERTER Figure 2. Measuring Input or Output Ripple 3 Downloaded from Arrow.com. QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1019A DUAL WHITE LED DRIVER CONVERTER 4 Downloaded from Arrow.com.