All About Circuits Forum  

Go Back   All About Circuits Forum > Electronics Forums > The Projects Forum

Notices

The Projects Forum Working on an electronics project and would like some suggestions, help or critiques? If you would like to comment or assist others with their projects, this is the place to do it.

Reply   Post New Thread
 
Thread Tools Display Modes
  #1  
Old 04-13-2012, 01:12 PM
rakeshm55 rakeshm55 is offline
Member
 
Join Date: Oct 2010
Posts: 53
Default Diode reverse current

Hi,
In one of the project I am working I am having two source of power one from a wall wart 5V and other a single Li ion Battery. I am using power ORing using PMEG3020EP schottky Diodes for automatic switch over of source.

The Li ion battery is also connected to a Single cell Battery charger a
XC6802 a Torex chip with input from the wall wart 5V.
When the battery is unconnected the chip periodically Pulses its output at an interval of 2.5ms as an attempt to charge the Li battery which is not present. In order to avoid this pulsing I have implemented N channel switch (Q4) which will disable charging when battery not present.
Please refer to the schematics attached.

Now The switch (Q4) is always on whether the battery is connected or not . This is mainly due to the reverse current of PMEG3020EP which is of the order of 0.2mA @ 5V reverse. Due to which I can observe the pulsing even when battery is disconnected. How can i solve this problem in the current setup. Is there a work around ,What if I replace R33 with a diode.

PLease help.
Regards
Rakesh M.






Attached Files
File Type: pdf Schematicst.pdf (34.8 KB, 19 views)
File Type: pdf 1-XC6802.pdf (350.4 KB, 14 views)
File Type: pdf PMEG3020EH_EJ.pdf (106.8 KB, 8 views)
Reply With Quote
  #2  
Old 04-14-2012, 12:24 AM
Ron H's Avatar
Ron H Ron H is offline
E-book Developer
 
Join Date: Apr 2005
Location: Idaho, USA (GMT-7)
Posts: 7,050
Default

I read the diode datasheet as Irev=30uA typical at 5V and 25C. See Fig. 2.
Reply With Quote
  #3  
Old 04-14-2012, 11:32 AM
rakeshm55 rakeshm55 is offline
Member
 
Join Date: Oct 2010
Posts: 53
Default



THe value of 0.2mA @ 5V was current I observed when connected VBAT pin to ground.
Reply With Quote
Reply   Post New Thread

Tags
, , ,


Related Site Pages
Section Title
Worksheet Bipolar junction transistors as switches
Video Lecture Power Supplies - Applications - Diodes and Diode Circuits
Textbook CMOS 555 LONG DURATION BLUE LED FLASHER : 555 Timer Circuits
Textbook Current mirrors : Bipolar Junction Transistors
Textbook Special-purpose diodes : Diodes And Rectifiers
Textbook Diode switching circuits : Diodes And Rectifiers
Textbook Diode ratings : Diodes And Rectifiers
Textbook Introduction : Diodes And Rectifiers
Textbook The P-N junction : Solid-state Device Theory
Textbook Valence and Crystal structure : Solid-state Device Theory


Similar Threads
Thread Thread Starter Forum Replies Last Post
Question about being killed with electricity... steev General Electronics Chat 55 05-30-2014 07:55 AM
diode current? noobuser Homework Help 0 10-20-2010 04:07 AM
relay to reverse polarity of 12v current on timer liv2plant General Electronics Chat 7 08-09-2009 08:52 PM
quick check ihaveaquestion Homework Help 23 05-07-2009 09:00 PM
Shunt regulator/Zener diode - current regulation for LEDs akirby General Electronics Chat 18 10-06-2007 01:11 PM

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT. The time now is 01:29 PM.


User-posted content, unless source quoted, is licensed under a Creative Commons Public Domain License.
Powered by vBulletin
Copyright ©2000 - 2014, vBulletin Solutions, Inc.