bobricius
At first big thanks Yann Guidon for eagle library for 4014 LED, and great idea with DYP LED project
I understand that this not practical watches, I calling my product
"party watch", not for daily usage but good eye catcher on special
occasions.
Standby time is acceptable, in good condition more than 7 days. If
anybody think that 5 minutes run-time is low? it is abut 300seconds if
you display time
for 3 seconds you can check time 100 times or 350 times in low brightness.
Charging:
Charging is very simple because vinatech scap are 3V, just I use 3V
fixed voltage LDO MCP1700T3002ETT with 10R resistor to limit charging
current + shottky diode
for protection reverse current to LDO .... charging voltage drop to
acceptable 2.95V
Discharging:
Heart is fixed 3V version of MAX1724 extremely low 1.5µA quiescent
supply current Step-Up DC-DC Converter which can work until 0.4V imput
voltage
I can use about 87% of stored energy. In all operation time I have
stable 3.001V for MCU.
I also have on board space for newest MAX17222 ... 300nA Iqc bu I am
unable to solder 6-Pin μDFN
Average consumption is now about 7uA.
MCU:
I am using PICOPOWER Microchip/ATMEL ATMEGA328 stanby consumption with
runing RTC is 0.9uA
Every seconds MCU wake form sleep for add second to counter and flash
led on gauge to show remaining capacity level.
If you press button you can show time, long hold adjust time ...
I am satisfied with results, I have something unique in world ... non
practical but unique ;)
Vishnu Mohanan
nolandoktor
CF
Alex Shakespeare
Totally awesome.
If you want to really extend the dark sleep life look at Ambiq 0815 RTC chips down to 14nA RTC current, and at 1.5V operation it would run direct from the BPW34's in standby.
Using a clock output from the RTC you might be able to have a flyback convertor to bootstrap the cpu VDD, without using a dedicated power IC