AN-1006 Datasheet, PDF (1/3 Pages) Cymbet Corporation – Backing Up Epson Toyocom Real-Time Clock Chips

AN-1006
Application Note
Backing Up Epson Toyocom Real-Time Clock Chips
A Demonstration Tool for Cymbet™ EnerChip™
Solid State Thin Film Rechargeable Batteries
is fully charged. At full charge, the current is in the sub-nanoamps. A
simple but effective technique prevents the battery from discharging
through the charging circuit or the power supply during primary
power outages.
The Cypress USB-to-I²C converter board was chosen to provide a
cost effective way of programming the Epson RTC-8564 JE real time
clock chip and to use the display and operating system of a notebook
computer to provide a graphical user interface (GUI). The board also
provides a convenient way to power the clock chip and charge the
Cymbet solid state battery.
Figure 1. Cymbet Demo Kit for Epson Toyocom RTC chips.
Introduction
Cymbet™ EnerChip™ solid state, thin film batteries are ideal
as rechargeable backup power sources for real-time clock
(RTC) chips, memories, microcontrollers and other low-power
circuits where data or timing information must be retained in
the absence of primary power. They come in standard
integrated circuit packages and can be reflow soldered for high
volume PCB assembly.
This application note describes a test/demo kit and test proce-
dures which allows a user to evaluate Cymbet batteries as a
backup for Epson Toyocom RTC chips. This system consists
of the following items:
1. Cymbet Epson RTC Demo Board (upper right in Figure
1). Includes a Cymbet CBC050 50-µAh battery, a Cymbet
CBC012 12-µAh battery, the same battery charging circuit
as Cymbet’s EVAL-01 board, and an Epson Toyocom
RTC-8564 JE real-time clock chip.
2. CD ROM with Cymbet software.
3. Cypress Semiconductor USB-to-I²C Bridge Kit, CY3240-
I2USB. Includes a USB-to-I²C converter board (upper left
in Figure 1) and a USB cable. Cypress kit or equivalent to
be furnished by user.
The Cymbet Epson RTC Demo Board uses the Cymbet
EVAL-01 circuit to charge an on-board Cymbet battery at a
constant voltage. Please see AN-1003 for details. As the
battery is charging, the charging current drops until the battery
To charge the battery, operate the system with the Demo Board
connected for at least 30 minutes. The battery will be charged to 80%
within 30 minutes and to 100% after 45 minutes. Please see AN-1003
for details on battery charging times.
System Operation
Overview
The demo system utilizes a Microsoft Windows™ based computer
with a USB interface. Upon connection, the RTC Demo Board will
have its time set or read via the computer. The Board will then be
disconnected from the USB-to-I²C converter, and the GUI will blank
the time display digits. When the Demo Board is again connected to
USB-to-I²C converter, the correct updated time will be shown by the
GUI since the RTC module has been powered by the Cymbet battery.
Installing the Software
Open the .zip file and copy the contents into a directory on your
computer. The files should include PSoCfirstTouchUSBNetLib.dll,
RTCDemo.exe and logo1.bmp. The software will not work if installed
on a network drive. To start the GUI, click on the RTCDemo icon. If
there is a warning, go to the Microsoft website, download the .net
Framework update, and install
http://www.microsoft.com/downloads/Search.aspx?displaylang=en
Running the System
Caution: to minimize the possibility of damaging the demo system,
make sure power is off whenever separating or mating the Demo
Board with the USB-to-I²C converter. Do this by turning off the RTC
power button in the GUI, or disconnect the USB connector at the
personal computer or USB-to-I²C converter board.
© Cymbet Corporation • 18326 Joplin Street, Elk River, MN 55330 • 763-633-1780 • www.cymbet.com
DOC-111006 RevA
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