DC1055A Analog Devices

Demo Circuit 1055 QUICK START GUIDE LTC3219 LTC3219 250mA Universal Nine Channel LED Driver DESCRIPTION the LTC3219 data sheet for more information on this WARNING process. There are 64 dimming states available for the universal LEDs. Do not look directly at operating LED. This circuit produces light that can damage eyes. The charge pump optimizes efficiency based on the volt- age across the LED current sources. The part powers up in 1x mode and will automatically switch to boost mode Demonstration circuit 1055 is a 250mA Universal Nine whenever any enabled LED current source begins to drop Channel LED Driver with two RGB displays and three out. The first dropout switches the part to 1.5x mode and white LEDs featuring the LTC3219. a subsequent dropout switches the part into 2x mode. The LTC3219 is a low noise charge pump designed to The part resets to 1x mode whenever a data byte is up- 2 drive nine universal LED current sources. The LTC3219 dated via the I C port. requires only five small ceramic capacitors to form a Design files for this circuit board are available. Call complete LED power supply and current controller. the LTC factory. The maximum display currents are set with an internal L, LTC, LTM, LT are registered trademarks of Linear Technology Corporation. Other product precision current reference. On/Off blinking, gradation, names may be trademarks of the companies that manufacture the products. 2 and intensity are achieved via an I C serial interface. See QUICK START PROCEDURE Demonstration circuit 1055 is easy to set up to evaluate 3. Connect DC1055 to the DC590 USB Serial Controller the performance of the LTC3219. Refer to Figure 1 for using the supplied 14-conductor ribbon cable as proper measurement equipment setup and follow the shown in Figure 1. procedure below: 4. With power off, connect the input power supply to NOTE. When measuring the input or output voltage ripple, care must be VBAT and GND with a series ammeter and a voltmeter taken to avoid a long ground lead on the oscilloscope probe. Measure the as shown in Figure 1. input or output voltage ripple by touching the probe tip directly across the VBAT and GND terminals. See Figure 2 for proper scope probe technique. Turn on and set the input power supply between 2.9 5. TM 5.5V. The DC1055 has an extra 4.7uF de-coupling ca- 1. Refer to the DC590 Quick Start Guide for QuikEval pacitor between VBAT and GND to help accommodate setup and software installation details. long VBAT source lead lengths. The DC590 board gets 2. Make sure the USB cable is connected between the its power from the USB cable. computer and the DC590 controller board. NOTE. Make sure that the input voltage does not exceed 6V. NOTE. If using the DC590B board, a specific DVCC voltage level may be selected. This is done by setting the VCCIO jumper on the 6. Run the QuikEval program. The program detects the DC590 board to one of the following settings: 3.3V, 5V, removed DC1055 and displays the LTC3219 control window for 2.7V or set to external if use of an external supply is desired. (shown in Figure 3). 1LTC3219 Figure 1. Proper Measurement Equipment Setup Figure 2. Measuring Input or Output Ripple 2