DS 1307 Vs PCF 8385 - sustaining supply

[sn_burki]

pcf8385

I am working on a project, in which i am using pcf 8385 and almost finished. my problem is that like 1307 we dont have 3v attachment in pcf 8385, now how to protect time in pcf 8385 in case of absence of power. Plz help me if any one knows here.
Secondly I want to ask if I want to conver my project on 1307 then the same coding of pcf 8385? or any change will take place????????

 

[roughwork2000]

Re: DS 1307 Vs PCF 8385

Hai
Have this simple idea,
What is PCF 8385 it’s a RTC?

 

[hugo]

Re: DS 1307 Vs PCF 8385

Hi,

Just take a look at these schematics :

**broken link removed**

**broken link removed**

and BTW DS1307 they"re not so accurate...

 

[sn_burki]

Re: DS 1307 Vs PCF 8385

Hugo what you mean by saying "and BTW DS1307 they"re not so accurate..."
my second question is that if i connect 3v/230mA battary, how long will it work????
my third question is why we need trimmer capacitor with crystal in PCF 8385 unlike in DS 1307????? how to get 99.99 % acurate time (method).

Regards.

 

[hugo]

Re: DS 1307 Vs PCF 8385

The battery is meant for backup only ... to keep the time when the power goes off...
We had recently at work a defective batch of DS1305 ...
They have a bad reputation in general ... google for more...
On the other hand PCF 8385 seems to be better...
"why we need trimmer capacitor with crystal in PCF 8385" if i remember correctly they can output an ~ 1 Hz signal and you can adjust it from that trimmer... for more read the data sheet

 

[CMOS]

Re: DS 1307 Vs PCF 8385

PCF8385 consumes more current than DS1307 in standby mode so backup battery won't last long.
PCF8383 = 10~50uA
DS1307 = 300nA