AN-1052: Operating the EnerChip™ in High Temp. Environments
EnerChip CC Circuit Description and Operation
The EnerChip CC is a surface mount device that contains a rechargeable battery with integrated battery
management that performs the charge control, discharge control, threshold voltage detection, and supply
supervisory functions all in one low-profile package. It operates over the range of 2.5V to 5.5V and the
switchover threshold voltage is adjustable. A block diagram of the EnerChip CC is shown in Figure 11.
Under normal operation, the RTC, MCU, sensor, or other device, derives its power from the main system supply,
which might be a large coin cell, prismatic cell, cylindrical batteries, or indirectly from wall power through a
voltage regulator. Because the EnerChip has very low self-discharge, it needs to be charged infrequently. To
maintain a charge of 90% or greater on the EnerChip when it has not been used as a backup power source
for prolonged periods, the EnerChip needs no more than one hour of charging time per month. Such a low
charging duty cycle presents a negligible parasitic load to the main power source, as the EnerChip charges
quickly and its charging current decays to just tens of nanoamperes when fully charged. The EnerChip CC
controls the EnerChip charging function internally. When main power is interrupted - as during line power
outages or when the main battery is removed for recharging or replacement, the backup power source provides
enough energy to maintain operation of the RTC, MCU, sensor, etc.
Figure 11. Block diagram of the EnerChip CC Thin Film Battery with Integrated Battery Management
EnerChip CC includes the following functional elements:
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Internal charge control circuit that converts a wide range of input voltages to a tightly regulated battery
charging voltage;
Battery cutoff circuit that disconnects the load from the embedded EnerChip when the discharge
voltage reaches a preset limit;
Output pin (RESET/) for driving an interrupt line on an MCU, indicating the system is in backup mode;
A voltage detection circuit allowing a user-selectable threshold switchover voltage;
A control line that enables and disables the internal charge pump to reduce power consumption when
the internal EnerChip does not need to be charged, and to mitigate temperature effects in applications
requiring such measures.
All of these features have been combined to create a backup power solution that eliminates the need for a
dedicated supply supervisory circuit, battery holder or socket, separate battery management circuitry, and a
conventional power source such as a coin cell or supercapacitor. The result is a compact, single-chip solution to
backup and embedded power.
©2012 Cymbet Corporation • Tel: +1-763-633-1780 • www.cymbet.com
Doc AN-72-1052 Rev A
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