CBC915 EnerChip Energy Processor
In all cases while in the MPPT state, the boost converter is isolated from the EnerChip(s), output capacitor,
and load. During MPPT mode, the load will be operating from the energy stored in the output capacitor and
EnerChip(s). Once the maximum peak power point is found, the CBC915 will then set the ISOLATE EN line high
to connect the boost converter to the power management circuits, then repeatedly pulse the CAP CHG pin low.
The periodic pulsing of EN CAP CHG/ pin low enables small amounts of charge energy to be transferred from
the boost converter to the output capacitor with each low pulse on the EN CAP CHG/ pin. While the output
capacitor is being charged, the CBC915 will monitor the output capacitor voltage on the VCAP pin. When the
output capacitor voltage rises to 2V, the CBC915 will stop pulsing and set the EN CAP CHG/ pin low continuously;
this state allows maximum energy to be transferred from the boost converter into the output capacitor. When
the output capacitor voltage reaches 3.4V, the CBC915 will set the EN VOUT/ line low, connecting the output
capacitor to the application system load. At the same time, the CBC915 will pulse the EC CHG/ line low and
pulse the CUTOFF RST line high, thereby connecting the EnerChip to the boost converter, output capacitor, and
applying power to the application system load. The MODE SEL3 pin controls the charging behavior. If MODE SEL3
is high, the output capacitor will charge and the System load will be powered before the EnerChips are charged.
If MODE SEL3 is low, the EnerChips will be charged before the system load is connected and the CBC915 will set
the EN VOUT/ line low, connecting the output capacitor and EnerChips to the load. On the CBC915-ACA, MODE
SEL3 is fixed high. The purpose for the MODE SEL3 pin is to select whether to power the system load before or
after the EnerChips are charged, so users can select the priority of whether the system load is powered quickly or
the batteries are charged quickly. The CBC915 then monitors the output of the boost converter; when the boost
converter is in regulation the CBC915 will simultaneously pulse low the EC CHG/, CAP CHG/, and MPPT/ pins.
This state indicates the output is turned on and the system is in regulation, which typically happens once the
EnerChips have nearly a full charge.
Calibration Function
The CBC915 features a calibration function to remove errors caused by unit to unit variation in the voltage
divider resistors (R1 and R2 of Figure 3) used to drive the ECFB input. The CALIBRATE/ pin has an internal pull
up resistor and can be driven by an open drain/collector output or switch contact. To calibrate apply 4.06V to the
V+ node. Then short the CALIBRATE/ pin to ground for approximately 100mS. The EC CHG LED/, MPPT LED/, and
CAP CHG/ pins will simultaneously pulse low when the CBC915 has stored its calibration values.
Operating Modes
MODE SEL0 and MODE SEL1 determine which transducer type is being used.
• Type 0: Electromagnetic transducers; input voltage range 0.5V to 4V after rectification and filtering.
• Type 1: Thermoelectric generators; input voltage range 400mV for startup. 200mV to 1V at matched
impedance.
• Type 2: Piezoelectric generators; input voltage range 4V to 20V after rectification, loaded to matched
impedance.
• Type 3: Photovoltaic cells; 900mV to 4V at matched impedance.
MODE SEL3 (not available on CBC915-ACA) dictates whether the EnerChips get charged before being connected
to the output (MODE SEL3 = low), or the Enerchips will begin charging when the output is connected to the
load (MODE SEL3 = high).
Type
0 (Electromagnetic)
1 (Thermoelectric)
2 (Piezoelectric)
3 (Photovoltaic)
MODE SEL3
X
X
X
X
MODE SEL2
X
X
X
X
MODE SEL1
Low
Low
High
High
MODE SEL0
Low
High
Low
High
DS-72-15 Rev F
©2012 Cymbet Corporation • Tel: +1-763-633-1780 • www.cymbet.com
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