The Flower Power reference design highlights Intersil’s 4.5V – 18V input switching regulator. This board utilizes the ISL85005, 5A device as a representative of this full line-up of wide-input switching regulators. Additionally, the board uses the ISL29102 Light to Voltage Sensor, the ISL21080 300nA NanoPower Voltage Reference and the ISL28915 Nano Power, Push/Pull Output Comparator. The board is powered from two Energizer CR2032 3V coin cell batteries and thanks to its low-power design, will be able to deliver over 1000 song cycles.
The Flower Power PCB is shaped like a 5-petal flower and comes in two colors, purple and yellow. It has 5 RGB LEDs on the front and an Intersil ambient light sensor to control the LED brightness. The flower features a Microchip MCU programmed to plays 5 songs while the LED lights flash in random patterns. Additionally the reference design:
- Displays a light pattern for low battery alert
- Automatically enters power savings mode
- Is powered with two CR2032 coin cell batteries; includes suction cup for hanging
- When start button is pressed, LEDs flash in a pattern to the melody of the 5 hippie-era songs: “Do You Believe in Magic,” “Are you Going to San Francisco,” “Here Comes the Sun,” “Age of Aquarius/Let the Sun Shine In,” and “Puff the Magic Dragon”
The following Intersil and partner products are featured in this reference design:
- ISL85005 – 4.5V to 18V Input, 5A High Efficiency Synchronous Buck Regulator
- ISL29102 – Low Power Ambient Light-to-Voltage Nonlinear Converter
- ISL21080 – 300nA NanoPower Voltage References
- ISL28915 – Nano Power, Push/Pull Output Comparator
- ATmega328P-AU – picoPower® technology 8-bit AVR® RISC-based (MCU)
- ASPI-0630LR series – Abracon molding type power inductor
- PKLCS1212E4001-R1 – Murata SMD piezoelectric sounder plus 7 capacitors
This reference design is intended to be a fun office adornment. Simply press the button on the back and the flower will play one of 5 classic “Summer of Love” songs and create an eye-pleasing color LED pattern on the petals. It comes with a suction cup hanger that can be used to hang the board on a window or any smooth surface.
|Flower Power Design Files
Gerber and Schematic Files for the Flower Power Reference Design Board
10 Mar 2017
|ZIP||10 Mar 2017||921 KB|
|ISL85005, ISL85005A Datasheet
Highly Efficient 5A Synchronous Buck Regulator
20 Mar 2017
|20 Mar 2017||2.06 MB|
Low Power Ambient Light-to-Voltage Nonlinear Converter
08 Mar 2017
|08 Mar 2017||1.12 MB|
300nA NanoPower Voltage References
13 Mar 2017
|13 Mar 2017||1.78 MB|
Nano Power, Push/Pull Output Comparator
13 Mar 2017
|13 Mar 2017||843 KB|
The ISL85005 was chosen to produce 3.3V rail which is used by the rest of the active components on the board. This regulator has an input voltage range of 4.5V-18V which was a primary reason for selecting this device because the two CR2032 batteries in series deliver a nominal voltage of 6V. Typically, switching regulators often have a maximum input of 5.5V and could therefore be damaged by the batteries. While the ISL85005 is capable of delivering up to 5A of output current, this design actually draws less than 50mA on the 3.3V rail during song-play. This low-current application shows off the Diode Emulation Mode (DEM) feature of the ISL85005 which greatly improves the efficiency at light loads.
The reference design used on the ISL85005 Evaluation Board was followed closely for this design. An Abracon ASPI-0630LR series 3.3uH power inductor was selected to be used in conjunction with the ISL85005 due to its low DC resistance and its high saturation current.
The flower board is populated with the ISL29102 light to voltage sensor. This sensor was added primarily to be used for future demos. While the flower reference design doesn’t use the light sensor as a normal sensor, it does make use of it to generate random numbers in the microcontroller. At power up, the micro reads the output of the ambient light sensor and then feeds that value as the seed for a random number generator. This enables the board to play a random song when the button is pressed rather than repeating the same song at each power-up.
Low Battery Detect
When the batteries near their discharge state, a low battery detect circuit alerts the user that it is time to change the batteries. This is indicated by all 5 LEDs flashing red for 10 seconds. This circuit uses the ISL21080 voltage reference and ISL28915 comparator. The battery voltage is divided down and compared to the 2.048v output of the ISL21080. If the battery voltage drops below 4.72V, the output of the comparator goes HIGH and the microcontroller commands all 5 LEDs to flash red. This feature can most easily be demonstrated by removing the batteries and powering the board with a programmable power supply set below 4.72V. An alternative approach to demonstrate this feature is by playing several songs consecutively which may cause the battery voltage to temporarily dip low enough to trigger this circuit.
Battery and Power-Down Control
The board is powered by two Energizer CR2032 3V batteries in series. This produces a nominal voltage of 6.0V with 240mA/hrs of life. The output of the battery voltage is fed to a power-down control circuit which connects the battery voltage to the input of the ISL85005 via a bi-polar transistor when the push-button is depressed. After the song cycle completes, a signal from the microcontroller triggers the power-down circuit to disconnect the battery from the rest of the board. Thanks to the extremely low leakage current during the off-cycle and the low current draw during song play, a fresh set of batteries should be able to power this reference design for >1000 song cycles before they’ll reach a low battery condition.
The LEDs used on this board are tri-color LEDs. Each LED package actually contains a red, green and blue LED. A different value of pull-up resistor was chosen for each color in order to create an equal light intensity out of each color. The microcontroller has control over each color and can therefore produce any color of the rainbow by changing the duty cycle of each RGB control line. For the reference design, there are 4 different LED patterns that can be used. At power up both the song and the LED pattern are chosen at random. The LEDs change color/intensity on each beat of the song.
The same ATmega328P-AU picoPower® technology 8-bit AVR® RISC-based (MCU) was used on this reference design as was used on the snowflake ornament reference design. The microcontroller was powered at 3.3V and the 8MHz internal oscillator was utilized to minimize component count. The code for the ATmega328P-AU was written in C via the Arduino IDE. The Arduino environment was selected because its simplicity decreases the learning curve and speeds time to market. While the hardware reference design files are available for download, we cannot release the C code because this code contains the copyrighted music that we have licensed for our use.