microGen LTC3330 User manual
Evaluation Kit
User’s Guide
2
Table of Contents
Product Description........................................................................................................ 3
Specifications ................................................................................................................. 4
AC Power Cell ................................................................................................................. 5
LTC3330 Power Management Board ............................................................................. 7
Torex LDO Power Management Board ........................................................................ 10
Connecting AC Power Cell to Power Management Boards ......................................... 11
Connecting two AC Power Cells................................................................................... 12
Diagnostic Board .......................................................................................................... 13
Board Overview..................................................................................................... 13
Connection Diagrams............................................................................................. 17
Frequently Asked Questions ....................................................................................... 19
Appendix....................................................................................................................... 21
3
Product Description
The Evaluation Kit is a modular and configurable kit that assists the user in efficiently assessing
vibrational energy harvesting for their application. Included are two vibrational piezoelectric AC
Power Cells, a Diagnostic Board, and two different Power Management Boards. The AC Power Cell
is a break-out board that provides the user easy connection points to the MEMs based piezoelectric
harvester. The AC Power Cell pairs with either of the two Power Management Boards, which rectify
and condition the harvested energy from the AC Power Cell. The Power Management Boards
provide up to 500µF storage capacitance for powering the application of interest. The LTC3330
Power Management Board is configurable to output between 1.8 and 5 Volts. The Torex LDO
Power Management Board has a fixed 3.3 Volt output.
The Diagnostic Board enables the user to quickly characterize the power consumption of low-
power electronic devices. The Current Sense Circuit has the flexibility to view different current
draw ranges via jumpers and an external oscilloscope (not provided). In addition, the Diagnostic
Board contains a Blinking LED Test Circuit that can be used as a direct load for the AC Power Cell,
or indirectly as a load for the Current Sense Circuit.
Figure 1: Evaluation Kit Contents
4
Specifications
AC Power Cell
Overview
Mass (g)
14.4
Capacitance (nF)
1.8 - 2.1
Dimensions (mm)
40.6 x 40.6 x 6.85
Device Package
68 pin QFN
Resonance Mode
Resonant Frequency (Hz)
500 - 700
Q Factor
> 200
Min acceleration low frequency (g)
0.5
Recommended max acceleration (g)
2.5
Maximum average AC power (µWatts)
200
Impulse Mode
Max acceleration (g)
~300
Recommended impulse duration (ms)
< 1
Impulse frequency* (Hz)
1-5
Est. power (µWatts)
5-40
*half-sine, 0.7ms base width, 300G
peak
5-10
40-70
10-20
70-100
LTC3330 Power Management Board
Torex LDO Power Management Board
Diagnostic Board
Harvesting Voltage Range
3 - 19 Volts
Output Voltage Range
1.8 –5 Volts
Storage Capacitance
500 µF
For more information about the LTC3330, please consult the Linear Technologies LTC3330 datasheet.
Operating Voltage Range
1.5 - 6 Volts
Output Voltage
3.3 Volts
Storage Capacitance
500 µF
For more information about the XC6215, please consult the Torex XC6215 datasheet.
Supply Voltage
9 Volts
Sense Resistor
10 Ohms
Sensing Range
10 uA –25 mA
Maximum Power Through Sense Resistor
0.125 Watts
LED flasher input voltage
2 –8 Volts
For more information about the INA326 Instrumentation Amplifier, please consult the Texas
Instruments INA326 datasheet.
5
AC Power Cell
Product Description
The microGen AC Power Cell allows the user to more readily probe and connect to microGen’s AC
Power Generator, our piezoelectric vibrational energy harvester. Simply mount the board to a
vibration source and the device will generate AC power. Connect one of the supplied Power
Management Boards and you are ready to generate DC power.
Figure 2: AC Power Cell
How it Works
The heart of microGen’s AC Power Cell is the AC Power Generator, a high-Q piezoelectric
vibrational energy harvester with a fixed frequency that is based on a cantilevered beam design.
The piezoelectric layer in the device is compressed and elongated as the cantilever moves in
response to an external vibration source, which generates charge that can be extracted for power.
To generate power, the AC Power Generator can interact with vibrations in the environment in
two different ways. In resonant mode of operation, the AC Power Generator couples directly with
a matching fixed and stable input frequency from the environment. The resonant movement of
the cantilever allows power to be generated at fairly low acceleration levels, depending on the
frequency used. Alternatively, when a stable, fixed frequency is not available, the AC Power
Generator can be driven in impulse mode of operation, where the harvester responds to the initial
shock input, and then continues to vibrate as it rings down at its natural frequency, much like a
tuning fork or a bell struck by its clapper, until the next impulse shock is received. During the
time the harvester rings down, power is generated. The amount of power that can be extracted
under these conditions depends on the resonant frequency of the harvester, sharpness and peak
acceleration of the shock, and time between shock inputs. For further discussions on your
particular application, please contact microGen Systems directly.
6
AC Power Cell Board Components
The AC Power Cell board contains the AC Power Generator, located at the center of the board,
and two 3-pin headers for connecting accessory boards (e.g. microGen’s Power Management
Boards) on top of the AC Power Cell, or the user’s custom electronics. Also included on the board
are configuration resistors that route the power signals, and loops for probe clips should the need
arise to view the harvester voltage output.
Connector
Pin
Number(s)
Connection
Type
IO Type
Description
P1
1
Header
Output
+ AC
P1
2
Header
Output
Ground
P1
3
Header
Output
- AC
P2
1
Header
N/A
Physical Support Only
P2
2
Header
N/A
Physical Support Only
P2
3
Header
N/A
Physical Support Only
Table 1: Connection list
Reference
Designator
Value
Description
+HV1
NA
+AC probe point
-HV1
NA
-AC probe point
+HV2
NA
Probe Point *
-HV2
NA
Probe Point *
R1
0 Ohm
Connect -HV1 to Ground *
R2
0 Ohm
Connect -HV1 to output P1
R3
0 Ohm
+HV2 to output P1 *
R4
0 Ohm
Connect screw holes to ground
R5
0 Ohm
-HV2 to ground *
R6
0 Ohm
Connect +HV1 to output P1
* Not used in standard single AC Power Cell configuration
Table 2: AC Power Cell board components
Mounting
It is essential to mount the AC Power Cell to the vibration source as securely as possible to ensure
vibrations are efficiently transferred to the AC Power Generator. The PCB has (4) mounting holes
to accommodate a standard #4-40 machine screw. Other methods of coupling, such as a strong
magnet, can also be used, as long as the AC Power Cell remains fixed and attached to the surface
of interest. Mounting hole locations can be seen on Figure 17 in the appendix.
7
Power Management Boards
In most instances, it is desirable to convert the output of the AC Power Cell to DC power. To
enable the user to do this quickly, the Evaluation Kit includes two Power Management Boards
which rectify the AC Power Cell output to DC power regulated to a constant voltage. It is
important to note that the harvesting power can be optimized by selecting the proper Power
Management Board for the application. For applications where the AC Power Cell creates a high
AC voltage (up to 20V), the LTC3330 Power Management board should be used. For applications
where in the AC Power Cell creates low AC voltages (less than 6V), the Torex Power Management
board should be used. For impulse mode of operation, selection of the best power management
board should be determined on an application by application basis. Please contact microGen
Systems for further discussions on your specific application.
LTC3330 Power Management Board
Product Description
The LTC3330 Power Management Board uses a low leakage single phase diode bridge to rectify
an AC voltage. A Linear Technologies LTC3330 nanopower DC/DC converter is laid out in a buck
configuration with a 22uH inductor. The switching converter allows for wide range on input
Voltages and a configurable output between 1.8 and 5 Volts. The board is designed to convert
the output power signal of the AC Power Cell to a useable DC power signal. The board connects
directly to the AC Power Cell via two 3-pin receptacles located at either end of the board.
Figure 3: LTC330 Power Management Board
8
How it Works
The AC signal from the AC Power Cell is routed directly to the Linear Technology LTC3330 AC/DC
converter component. The LTC3330 is highly configurable, allowing the user to adjust the output
voltage as well as the voltage range where the device is allowed to harvest energy. The user has
the option to use the onboard capacitance for power storage, or bypass the storage capacitors if
all of the harvested energy is to be transferred off the PCB. This provides the user with a stable
DC power source.
LTC3330 Power Management Board Components
Two 3-pin receptacles are used to connect to the LTC 3330 Power Management Board to the AC
Power Cell. The resulting DC output voltage can be accessed via connector P7 or P8. Additional
headers are provided for connecting to other accessory boards and/or for powering a device with
energy harvesting.
Connector
Pin
Number(s)
Connection
Type
IO
Type
Description
P1
1, 2, 3
Header
N/A
Physical Support Only
P7
1
Header
Output
VDC Out
2
Header
Output
Ground
3
Header
N/A
Not Used
P2
1
Receptacle
Input
AC1 Input
2
Receptacle
Input
Ground
3
Receptacle
Input
AC2 Input
P9
1, 2, 3
Receptacle
N/A
Physical Support Only
P8
1
PicoBlade
Header
Output
VDC Out
2
PicoBlade
Header
Output
Ground
VOUT0
1, 2, 3
Header
Input
Output Voltage Configuration Bit
VOUT1
1, 2, 3
Header
Input
Output Voltage Configuration Bit
VOUT2
1, 2, 3
Header
Input
Output Voltage Configuration Bit
UVLO0
1, 2, 3
Header
Input
Harvesting Voltage Configuration Bit
UVLO1
1, 2, 3
Header
Input
Harvesting Voltage Configuration Bit
UVLO2
1, 2, 3
Header
Input
Harvesting Voltage Configuration Bit
UVLO3
1, 2, 3
Header
Input
Harvesting Voltage Configuration Bit
Bypass/Caps
1-6
Header
Switch
Toggle in/out Onboard Capacitors
Table 3: Board Pinout
9
Configurations
The output voltage of the LTC3330 Power Management Board is configurable by the user. Use
the provided VOUT jumpers and Table 4 for proper configuration. Note that the LTC3330 only
operates in DC/DC Buck Mode so the output voltage cannot equal to or greater than the user
configured harvesting input voltage.
VOUT2
VOUT1
VOUT0
Output
Voltage
0
0
0
1.8V
0
0
1
2.5V
0
1
0
2.8V
0
1
1
3.0V
1
0
0
3.3V
1
0
1
3.6V
1
1
0
4.5V
1
1
1
5.0V
Table 4: Output Voltage Configurations
Depending on the strength of the vibration, there may be an optimum input voltage range to
harvest from. Table 5 shows the configurations available. If using the harvester in resonant mode,
it is recommended that the harvesting voltage range chosen encompass a voltage approximately
½ the peak AC voltage generated by the harvester WITHOUT loading (the “open circuit” voltage).
If using the harvester in impulse mode, typically the lowest voltage range is chosen that can still
provide the desired output voltage (e.g., to use the 3.3V output setting, the lowest usable range
is the 4-5V range since this chip uses a buck regulator).
UVLO0
UVLO1
UVLO2
UVLO3
ULVO
RISING
UVLO
FALLING
0
0
0
0
4V
3V
1
0
0
0
5V
4V
0
1
0
0
6V
5V
1
1
0
0
7V
6V
0
0
1
0
8V
7V
1
0
1
0
8V
5V
0
1
1
0
10V
9V
1
1
1
0
10V
5V
0
0
0
1
12V
11V
1
0
0
1
12V
5V
0
1
0
1
14V
13V
1
1
0
1
14V
5V
0
0
1
1
16V
15V
1
0
1
1
16V
5V
0
1
1
1
18V
17V
1
1
1
1
18V
5V
Table 5: Input Voltage Harvesting Threshold Configurations
10
Torex LDO Power Management Board
Product Description
The Torex Power Management Board uses a low leakage single phase diode bridge to rectify an
AC voltage into an LDO (low-dropout regulator). The Torex XC6215 is a low power consumption
Voltage regulator that provides a fix 3.3 Volt output. The components chosen are designed to
provide an efficient AC to DC conversion. The board is designed to connect directly to the AC
Power Cell via two 3-pin receptacles located at either end of the board. This LDO solution works
best with input voltages lower than 6 Volts AC.
Figure 4: Torex Power Management Boar
How it Works
The AC signal from the Harvester Board is rectified through a diode bridge and passed into a
Torex XC6215 low dropout regulator. A low-dropout regulator is a DC linear voltage regulator that
can regulated the output voltage even when the supply voltage is very close to the output voltage.
The user has the option to use the onboard capacitance for power storage, or bypass the storage
capacitors if all of the harvested energy is to be transferred off the PCB. This provides the user
with a stable DC power source.
11
Torex Power Management Board Components
Two 3-pin receptacles are used to connect the Power Management Board to the AC Power Cell.
The resulting DC output voltage can be accessed via connector P7 or P8. Additional headers are
provided for connecting to other accessory boards and/or for powering a device with energy
harvesting.
Connector
Pin
Number(s)
Connection
Type
IO Type
Description
P1
1, 2, 3
Header
N/A
Physical Support Only
P7
1
Header
Output
+ VDC
2
Header
Output
Ground
3
Header
N/A
Not Used
P2
1
Receptacle
Input
AC1 Input
2
Receptacle
Input
Ground
3
Receptacle
Input
AC2 Input
P8
1
PicoBlade
Header
Output
VDC Out
2
PicoBlade
Header
Output
Ground
P9
1,2,3
Receptacle
NA
Physical Support Only
Bypass/Caps
1-6
Header
Switch
Toggle in/out Onboard Capacitors
Table 6: Board Pinout
Connecting Power Management to AC Power Cell
To properly connect the AC Power cell to one of the Power Management Boards P2 on the Power
Management Board must align with P1 on the AC Power Cell. Figures 5 and 6 show the correct
orientation of the boards. Please note the microGen logo in each picture and how they align
differently on the two Power Management Boards.
Figure 5: LTC3330 and AC Power Cell
Figure 6: Torex LDO and AC Power Cell
12
Connecting Two AC Power Cells
Both of the AC Power Cells included in the Evaluation Kit can be used in conjunction to increase
the amount of energy harvested. This requires the user to modify one of the AC Power Cells to
match the resistor configuration pictured in BOARD A. To modify BOARD A, remove R2 and install
R1. The allows both AC Power Cells to share a common ground.
Board B must remain as the user received it. R3 and R5 may remain on both boards but not
shown below on BOARD B as they are not used. The user must undo this modification when using
BOARD A by itself.
Connect BOARD A, the modified AC Power Cell
,
to one of the Power Management Boards supplied
and use jumpers to connect Board B to BOARD A. Output connector P1 on Board B connects to
Board A using probe points (-HV2 and +HV2).
Figure 7: Two AC Power Cell Connection Schematic
13
Diagnostic Board
Product description
The Diagnostic Board provides the user with several tools to analyze the current consumption of
their device and current generated from the rectified output of the AC Power Cell. It contains a
low power Current Sense Circuit based on a Texas Instruments INA326 Instrumentation Amplifier
that enables measurement of current with low noise levels. Gain configuration jumpers allow the
user to view different current draw ranges via an external oscilloscope (not provided).
The Diagnostic Board requires a power source to for the INA326. An external AC/DC adapter is
provided, but a 9V battery can also be used when operating in remote locations. In addition to
the Current Sense Circuit, the Diagnostic Board contains a Blinking LED Test Circuit that can be
used as a direct load for the rectified output of the AC Power Cell, or indirectly as a load for the
Current Sense Circuit.
Figure 8: Diagnostic Board
14
Diagnostic Board Overview
Figure 9: Diagnostic Board Overview
Current Sense
Circuit Supply Input
Voltage (9VDC)
9V Battery Holder
Device Input Power
Terminal Block
Rectified AC Power Cell
DC Input Connector
Device/Load
Terminal Block
Blinking LED
Test Circuit
Rectified Power Cell
DC Input Connector
Oscilloscope
Probe Clip Loops
15
Current Sense Circuit
The Current Sense Circuit allows the user to connect a DC input (such as a battery, benchtop
supply or the rectified output of the AC Power Cell + Power Management Board) and a load device
through a low-side 10 Ω sense resistor (see Figure 10). Using an external oscilloscope, the user
can view the amplified current signal. This allows the user to quantify the current draw of their
device. The gain settings of the amplifier allow the user to measure current more accurately
without losing accuracy over the full measurement range of the device. The three current sensing
ranges overlap so there is no loss of continuity.
Figure 10: Current Sense Circuit
16
Gain Jumper Configurations
The Current Sense Circuit is able to measure current over a wide range (10 µA to 25 mA).
However, the full range is binned into three groups to ensure complete coverage of the current
sensing range. See Table for the gain jumper configurations. Note any configuration not show in
Table 7 is invalid.
Gain
Minimum
Current
Maximum
Current
JP1
Configuration
P6 Configuration
20
510µA
25mA
500
20µA
980µA
10,000
10µA
49µA
Table 7: Gain Configurations
Blinking LED Test Circuit
The Diagnostic Board also contains a Blinking LED Test Circuit. This test circuit is primarily used
as a quick indicator that DC output is being generated from the AC Power Cell rectified and
conditioned by a Power Management Board, but it can also be used as a test load for the Current
Sense Circuit. Use the configuration Figure 13 in the Connections Diagrams section.
17
Connection Diagrams
Below are three common configurations to utilize the contents of the Evaluation Kit. Terminal
block (P2) or Molex PicoBlade™ connector (P3) allow the user to connect an independent power
supply (e.g. battery, bench-top supply) or the rectified output of the AC Power Cell as the input
power source of the attached load or device as shown in Figure 11.
To characterize the energy harvested from the AC Power Cell and the user’s vibrational source
use Figure 12. To properly measure the power generated a load must be used (e.g. 150K Ohm
resistor).
The Blinking LED Test Circuit may be used as a load for the rectified output of the AC Power Cell
when connected as shown in Figure 13. Also the LED provides a quick visual confirmation that
energy is being harvested
Figure 11: Measuring Current Draw of a Device from a Power Source
Oscilloscope
Device/Load
Power Supply (P2)
Power Supply or
Power Cell (P3)
18
Figure 12: Measuring the Current Draw using the rectified output of the AC Power Cell
Figure 13: Using the Blinking LED Test Circuit as a Load
Oscilloscope
DC Input (AC Power
Cell + Power
Management Board)
Load
Oscilloscope
microGen Power Cell
19
Frequently Asked Questions
Q: The output of the Current Sense Circuit is just noise, what’s wrong?
A: There could be several reasons for lacking a signal. Please check the following:
Ensure Diagnostic Board is powered via the external DC port or with a 9V battery.
oThe Texas Instruments INA326 Instrumentation Amplifier requires power to
amplify the current draw signal.
Ensure the power switch is in the ON position.
oThe power switch controls the power to the circuit. When using a battery, it is
convenient to just turn the board off rather than removing the 9V battery.
Ensure the gain setting is properly configured using jumpers.
oIt is possible to configure invalid gain settings.
Ensure the input wires of the Current Sense Circuit are secure in the terminal blocks.
The amplifier of the Current Sense Circuit has a measurement floor below which current
cannot be measured. Any current draw below this level will appear as noise.
Q: My output from the Current Sense Circuit is sometimes railed to ~5V (or ~0),
how is this possible?
A: The amplified on the Current Sense Circuit has (3) gain settings. Each setting is only capable
of reading a certain range of current. Sensed currents that are above the configured range
appear as ~5V and sensed currents that are below the configured range appear as ~0V.
Configure the gain setting jumpers accordingly to view the high end and/or the low end signal.
Q: I’m not getting the power levels that I was expecting, what’s wrong?
A: There could be several reasons for lack of power. Please check the following:
Ensure the g level of the vibration source is above the minimum to excite the AC Power
Generator. For impulse mode of operation, this is highly dependent on the pulse width
and maximum g level of the pulse. Please contact microGen Systems for further
information.
Ensure the AC Power Cell is rigidly mounted.
oTo transfer the maximum amount of vibration to the AC Power Cell, ensure the
PCB board is securely fastened to the vibration source. Mounting options include
using the provided mounting holes, double-sided tape, or a self-adhesive
magnet.
20
Q: My AC Power Cell rectified through the Power Management Board can generate a
DC voltage but the device I’m trying to power won’t start up; why?
A: On initial power up, many devices draw much more current than when they are in typical
operation. This is may be due to decoupling caps and other components charging up from an
empty state. To ensure the device can power up, add enough charge storage (e.g. capacitance,
rechargeable battery) to get through the initial power hungry state. Some chips require rapid
voltage turn-on to trigger a “power-on-reset”. If this is the case, you can allow the storage
capacitors on the power management board to charge up, then manually connect the device of
interest.
Q: My device uses too much power and drains my storage device too quickly; what
can be done about this?
A: If your device uses a microprocessor remember to disable all unnecessary functions such as
unused timers. Using an efficient operating strategy is also key. If you’re using a device that
transmits RF, transmit only when necessary since the transmission uses the most power. Also
remember to use electronic components with low leakage currents.
Q: My LTC3330 Power Management Board doesn’t appear to be harvesting, what’s
wrong?
A: The LTC3330 is designed to allow the user to select the appropriate input harvesting voltage
(application dependent). Ensure the UVLO jumpers are properly configured. Please see the
Linear Technology LTC3330 datasheet for more information about the voltage ranges and their
respective settings.
Q: The output voltage of my LTC3330 Power Management Board isn’t what I
expected it to be, why?
A: The LTC3330 is designed to allow the user to select the output voltage. Ensure the VOUT
jumpers are properly configured. Please see the Linear Technology LTC3330 datasheet for more
information about configuring the output voltage. Please note that the LTC3330 is designed
only for bucking mode, meaning the input voltage must always be higher than the output
voltage. The boosting capability is not available when using an energy harvester as an input
voltage source.
Q: I want to connect to connector P8 (Molex PicoBlade™), what are the part
numbers for the contacts and housing?
A: The housing part number is Molex 51021-0200. The crimp terminals are Molex 50079-8100
for 26-28 AWG.
Q: I have two AC Power Cells. Can I connect both to one Power Management Board
to increase my power output?
A: Yes, two AC Power Cells can be connected to one Power Management Board, follow the
instructions in the Connection Two Power Cells section (page 12). The negative line of each unit
should be tied together and connected to the Ground line of the Power Management Board.
Attach one of the positive lines to one of the Power Management Board AC inputs, then attach
the remaining positive line to the remaining AC input. Now each AC Power Cell is sharing half of
the diode bridge it is attached to.
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