DS-72-40 Datasheet, PDF (6/17 Pages) Cymbet Corporation – EnerChip™ CC Energy Harvester Evaluation Kit

CBC-EVAL-10B EnerChip CC EH Evaluation Kit
Operating Modes
CBC-EVAL-10B can be configured to operate in any of three modes, as required by the application. The
operating mode is set by configuring the various jumpers on the CBC-EVAL-10B. [See Figure 3 and the
associated tables for jumper settings associated with each of the operating modes.] The three operating
modes are as follows:
Standard energy harvesting mode using PV cells, on-board EnerChips, clamped output voltage, and switchover
control circuit to ensure a seamless transition from PV power to EnerChips when little or no ambient light is
available. In this mode, power from the PV cells is used to power the system load and charge the EnerChips
when sufficient light is available. With very low or no ambient light, the system operates from on-board
EnerChips. Variations of this mode are configured using jumper select pins J11, allowing the user to drive the
internal charge pump of the CBC3150 through one of three control methods, as indicated on the silk screen
next to J11:
a) EH: External control using the BATOFF control line. Used when an external microcontroller derives
input from CHARGE/ in an ‘energy-aware’ operating mode.
b) CCEH: CBC3150 RESET/ output is fed to CBC3150 ENABLE input in a standard transducer
impedance matching mode.
c) CPEH: VIN controls the CBC3150 ENABLE line. When the input transducer voltage falls below 2.5V,
the CBC3150 charge pump is disabled.
“Battery Assist” Hybrid Energy Harvesting/Battery Configurations
The Primary Hybrid EH configuration relies on not only the on-board EnerChips for energy storage, but also taps
into the capacity of a conventional non-rechargeable battery when the EnerChips are at low state-of-charge
(such as during extended periods of darkness). Typical primary batteries might be 2-series alkaline cells, coin
cells, or certain cylindrical cells having output voltage of 3V to 3.6V. This ‘battery assist’ energy harvesting
mode can be used to supplement conventional batteries, extending their operational life by months or years.
Rechargeable Hybrid EH configuration uses not only the PV cells and on-board EnerChips, but also an external
rechargeable battery such as a rechargeable coin cell or other small, Li-ion or Li-polymer cells having a
charging voltage of ~4.1V. This ‘extra capacity’ operating mode allows the designer to incorporate a higher
capacity rechargeable battery in order to achieve longer system run-time in periods of darkness than what the
EnerChips can provide, while avoiding the relative bulk associated with non-rechargeable cells.
In all operating modes, the input power source - whether PV cells, EnerChips, or external battery - passes
through a integrated voltage dropping diode that supplies power to VOUT at 0.5V lower than the EnerChip
voltage of 3.7-3.9V. The output voltage is then typically 3.2 to 3.4V with light loading. The output voltage is
switched on by power-on-reset (POR) circuit when the current-pulse capacitors reach 2.9 volts the first time
since they were discharged. To avoid starving the external system elements of power particularly during start-
up or when pulse currents are required by the system, the POR circuit enables the output only after the output
capacitors are fully charged to a voltage above the 2.9V voltage. Consequently, the user must recognize the
relationship between the POR trip voltage and the output turn-on voltage when designing with a POR/LDO
combination other than the components installed on the CBC-EVAL-10 module.
EH Status LED and Push Button Switch
The Eval-10B also includes a switch and LED combination that is connected to the output POR circuit and
indicates whenever the output capacitors are above 2.9V. When the switch is pressed the LED turns on and
draws the output capacitors down to 2.9V where the LED turns off until the POR detects the output capacitor
voltage rising above 2.9V when the LED turns on again and the cycle repeats. This allows qualitative indication
of the available power by the speed the LED blinks.
©2014 Cymbet Corporation • Tel: [phone] • www.cymbet.com
DS-72-40 Rev C

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