CBC34813 EnerChip™ RTC

©2013 Cymbet Corporation • Tel: +1-763-633-1780 • www.cymbet.com

DS-72-38 V.01

Page 5 of 9

Preliminary

Important Reference Documents

For complete specifications of the integrated AM0813 Real-Time Clock, see here:

http://ambiqmicro.com

For complete specifications of the Cymbet 5µAh EnerChip and integrated power management circuit, reference

the CBC3105 datasheet here: http://www.cymbet.com/pdfs/DS-72-21.pdf .

The EnerChip and power management functions within the CBC34813 are configured as in Mode 1 (VMODE =

GND) as described in the CBC3105 DS-72-21 data sheet.

For guidelines regarding crystal selection and other important information pertaining to the AM0813, see here:

http://ambiqmicro.com/resource-center/

Functional Description of Integrated AM0813 Real-Time Clock

The AM0813 serves as a full function RTC for host processors such as microcontrollers. The AM0813 includes 3

distinct feature groups: 1) baseline timekeeping features with 32.768 kHz oscillator and 2) advanced

timekeeping features, and 3) basic power management features. Functions from each feature group may be

controlled via memory mapped registers. These registers are accessed using either an I2C serial interface (e.g.,

in the AM0803) or a SPI serial interface (e.g., in the AM0813). For more information on the AM0813, see here:

http://ambiqmicro.com/0800-series.

Low Power Operation

Minimum power operation will be achieved by turning off the charge pump in the power management circuit by

driving ENABLE low once the internal EnerChip has been charged - typically one hour to full charge at room

temperature.

The RTC has 3 low power modes, allowing the designer to make appropriate trade-offs between power

consumption and timing accuracy. Operating current drawn by the RTC is as follows:

<15 nA with RC oscillator

<20 nA with RC oscillator and autocalibration

<55 nA with crystal oscillator

In addition to the RTC current, the integrated power management circuit typically draws 20-25nA from the

EnerChip storage device at room temperature.