EnerChip CC CBC3105

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DS-72-21 Rev E

Page 9 of 12

Preliminary

EnerChip CC Detailed Description

The EnerChip CC uses a charge pump to generate the supply voltage for charging the integrated energy storage

switchover.

Operating Modes

The EnerChip CC can be operated from various power supplies such as a primary source or a non-rechargeable

battery. With the ENABLE pin asserted high, the charge pump is active and charges the integrated EnerChip.

The EnerChip CC will be 80% charged within 10 minutes. Due to the rapid recharge it is recommended that,

once the EnerChip CC is fully charged, the user de-assert the ENABLE pin (i.e., force low) to reduce power

consumption. A signal generated from the MCU could be used to enable and disable the EnerChip CC.

When controlling the ENABLE pin by way of an external controller - as opposed to fixing the ENABLE line to VDD

- ensure that the ENABLE pin is forced low by the controller anytime the RESET line is low, which occurs when

the switchover threshold voltage is reached and the device is placed in backup mode. Although the internal

charge pump is designed to operate below the threshold switchover level when the ENABLE line is active, it

is recommended that the ENABLE pin be forced low whenever RESET is low to ensure no parasitic loads are

placed on the EnerChip while in this mode. If ENABLE is high or floating while VDD is in an indeterminate

state, bias currents within the EnerChip CC could flow, placing a parasitic load on the EnerChip that could

dramatically reduce the effective backup operating time.

The EnerChip CC supports 2 operational modes as shown in Figures 6 and 7.

Mode 1 Operation

switchover threshold at approximately 3.0 volts.

Figure 6: CBC3105 Typical Circuit for Mode 1 Operation