AL3158 Evaluation Module HIGH EFFICIENCY CHARGE PUMP WHITE LED DRIVER Device Features Description • • • The AL3158 is a low noise, constant frequency charge pump DC/DC converter that uses a dualmode load switch (1x), and (2x) conversion for white LED applications. The AL3158 is capable of driving three groups of three LED channels at 20mA from a 2.7V to 5.5V input. The current sinks may be operated using three simple PWM dimming inputs individually or in parallel for driving higher current LEDs. Low external part counts (one 1μF flying capacitor and two 2.2μF capacitors at VIN and VOUT) make this part ideally suited for small, battery-powered applications. • • • • • • • • • • • VIN Range: 2.7V to 5.5V Up to 93% Max Power Efficiency 1% Current Matching Accuracy Between Channels Three Simple PWM Dimming for RGB or WLED Low Transition Threshold Voltage Typical 150 mV Dual-Mode 1x and 2x Charge Pump Drives up to 3 + 3 + 3 Channels of LEDs 1.2 MHz Constant Switching Frequency VOUT Short-Circuit and Thermal Protections Soft Start for Reducing Inrush Current Under Voltage Lockout Protection IQ <1μA in Shutdown Thermally-Enhanced QFN3030-20 Package: Available in “Green” Molding Compound (No Br, Sb) Lead Free Finish/ RoHS Compliant This evaluation board uses the AL3158’s three PWM dimming inputs to enable and disable the device and to control the current level of R, G and B elements of the three color LEDs. Each PWM input controls three LEDs of the same color. The PWM signals are generated by an on-board microcontroller with three push buttons for adjusting current levels. Ordering Information Device Package Code Packaging EVM Part Number AL3158FSG FS DFN3030-20 AL3158FSG-EVM Rev.2 AL3158FSG-EVM Rev.2 1 of 5 www.diodes.com SEPTEMBER 2010 © Diodes Incorporated AL3158 Evaluation Module HIGH EFFICIENCY CHARGE PUMP WHITE LED DRIVER Schematic AL3158FSG-EVM Rev.2 2 of 5 www.diodes.com SEPTEMBER 2010 © Diodes Incorporated AL3158 Evaluation Module HIGH EFFICIENCY CHARGE PUMP WHITE LED DRIVER PCB Layout Top Layer Layout of AL3158FSG-EVM Rev.2 Bottom Layer Layout of AL3158FSG-EVM Rev.2 AL3158FSG-EVM Rev.2 3 of 5 www.diodes.com SEPTEMBER 2010 © Diodes Incorporated AL3158 Evaluation Module HIGH EFFICIENCY CHARGE PUMP WHITE LED DRIVER Bill of Material Bill of Material for AL3158FSG-EVM Rev.2 Ref C1, C3 C2, C5 C4 LED1-3 LED10 LED11 JP1-9 JP10 R1-3 R4-5, 7-9 R6 R10-12 U1 U2 Count Size Mfr 2 0603 STD 2 0603 STD 1 1210 STD 3 0805 STD 1 0603 STD 1 0603 STD 9 0603 STD 1 0803 STD 1 0603 STD 5 0603 STD 1 0603 STD 3 0603 STD DFN3030-20 1 Diodes 0 1 QFN6060-28 Microchip Part Number STD STD STD LTST-C19FD1WT STD STD STD STD STD STD STD STD AL3158SFG PIC16F1827 Description 2.2 µF/10V ceramic capacitor 1 µF/16V ceramic capacitor 10 µF/10 ceramic capacitor RGB color LED Green LED Red LED 0 Ω resistor 0 Ω resistor Not populated 1 kΩ resistor 10 kΩ resistor 100 kΩ resistor Charge pump WLED driver 8-bit microcontroller I/O Terminals and Test Points Terminals and Jumpers for AL3158FSG-EVM Rev.2 I/O and Test Points Description Comments P1 (VIN), P2 (GND) P3 Power Supply and Ground Connect to input power supply Control signal monitoring Use an oscilloscope to monitor the PWM signals J11 Input Jumper to AL3158 Jumper for connecting VIN to the AL3158 J12 Input Jumper to PWM control Jumper for connecting VIN PWM controller circuit VIN, VOUT Voltage Test Points AL3158FSG-EVM Rev.2 Input and output voltage test points 4 of 5 www.diodes.com SEPTEMBER 2010 © Diodes Incorporated AL3158 Evaluation Module HIGH EFFICIENCY CHARGE PUMP WHITE LED DRIVER Quick Start Guide 1. Insert jumper J11 to connect VIN to the AL3158 and J12 to connect VIN to the onboard PWM controller. 2. Connect a +2.7V~+5.5V power supply between VIN (P1) and GND (P2) headers. Turn on the power supply. The red power indicator LED (LED11) will be on. 3. The PWM controller will enter State 1, where three different PWM signals are sent to the AL3158 to set the current levels of the three groups of LEDs, green, red and blue. Each group will be dimming from bright to dark and from dark to bright, causing LED1-3 to show changing colors. 4. In State 1, the green LED10 will be blinking. Pressing the UP and DOWN buttons will change the rate at which LED10 blinks and also change the dimming rate of the color LEDs. 5. Press the CYCLE button to move the PWM controller to the next state. Every time the controller enters a new state between States 2 and 4, the corresponding LED group will be dimming automatically while the other LEDs will stay at the current levels set in the previous States. 6. While in any state between State 2 and State 4, press the UP or DOWN button to stop auto-dimming. Then use the UP button to manually increase the brightness of the LEDs and DOWN button to decrease it. Press the CYCLE button again to resume auto-dimming of the same color. 7. Press the CYCLE button while in State 4 will bring the PWM controller back to State 1. 8. Press and hold the CYCLE button at any time will force the PWM controller to enter State 0. In this state, all color LEDs will be turned off. So will the green LED10. Press the CYCLE button in State 0 will change the PWM controller state to State 1 with all three color LED groups dimming in-synch, resulting in white color. 9. In order to see only one of the three colors, do the following: (1) Do step 8 and then enter State 1. (2) Follow step 4 to slow down the dimming rate. (3) Press the Cycle button while all color LEDs are off so that State 2-4 can be entered with the LEDs of only one color on. Table: PWM Controller Machine States Controller State Green LED (LED10) 0 Off 1 Flashing 2 On Description All RGB LEDs are turned off All three groups auto-dimming; UP and DOWN button to change dimming rate. Set current level for the green LEDs in LED1-3 3 On Set current level for the red LEDs in LED1-3 4 On Set current level for the blue LEDs in LED1-3 AL3158FSG-EVM Rev.2 5 of 5 www.diodes.com SEPTEMBER 2010 © Diodes Incorporated