<div dir="ltr">Hi Olav <div><br></div><div>Why don't do it easy and use a MOSFET and a 12V relay. Then you don't need to worry about heat and 5V power consumption.</div><div>See attached picture sample circuit. You should probably also add a resistor from the output of the PIC to GND to make sure the relay is turn properly off.</div>
<div><br></div><div>Regards, Thomas </div><div><br></div><div><br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">2014-06-17 10:04 GMT+02:00 Olav A. Antonsen <span dir="ltr"><<a href="mailto:olav@ansit.no" target="_blank">olav@ansit.no</a>></span>:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div lang="EN-US" link="blue" vlink="purple"><div><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Seems like most car phone chargers uses a MC34063 switchmode-regulator chip that is much more efficient than a 7805. Will strip one out of its casing and give it a try.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">For stronger currents I was told to use a UBEC.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">--Olav<u></u><u></u></span></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <a href="mailto:ovmsdev-bounces@lists.teslaclub.hk" target="_blank">ovmsdev-bounces@lists.teslaclub.hk</a> [mailto:<a href="mailto:ovmsdev-bounces@lists.teslaclub.hk" target="_blank">ovmsdev-bounces@lists.teslaclub.hk</a>] <b>On Behalf Of </b>Mastro Gippo<br>
<b>Sent:</b> 17. juni 2014 09:38</span></p><div><div class="h5"><br><b>To:</b> OVMS Developers<br><b>Subject:</b> Re: [Ovmsdev] OVMS - HW<u></u><u></u></div></div><p></p><div><div class="h5"><p class="MsoNormal"><u></u> <u></u></p>
<div><div><p class="MsoNormal">Olav, the temperature should not raise that much, as the PCB is dissipating some of the heat. You can just try it and see if it heats up too much (being careful not to blow the fuse, as Mark said), or use your own 7805 slapped to a small heatsink. If you need more power, a car phone charger may be a better choice as it has a more efficient switching supply.<u></u><u></u></p>
</div><p class="MsoNormal">MG<u></u><u></u></p></div><div><p class="MsoNormal" style="margin-bottom:12.0pt"><u></u> <u></u></p><div><p class="MsoNormal">2014-06-17 8:44 GMT+02:00 Olav A. Antonsen <<a href="mailto:olav@ansit.no" target="_blank">olav@ansit.no</a>>:<u></u><u></u></p>
<blockquote style="border:none;border-left:solid #cccccc 1.0pt;padding:0cm 0cm 0cm 6.0pt;margin-left:4.8pt;margin-right:0cm"><div><div><p class="MsoNormal">100°C/W!  9V * 0.2A = 1.8W => I need to keep the relays closed for 1 hour so it’s going to overheat!<u></u><u></u></p>
<p class="MsoNormal"> <u></u><u></u></p><p class="MsoNormal">Need to find another solution for feeding the relay module with +5V.<u></u><u></u></p><p class="MsoNormal"> <u></u><u></u></p><p class="MsoNormal">Mastro, any suggestions?<u></u><u></u></p>
<p class="MsoNormal"> <u></u><u></u></p><p class="MsoNormal">--Olav<u></u><u></u></p><p class="MsoNormal"> <u></u><u></u></p><p class="MsoNormal"> <u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <a href="mailto:ovmsdev-bounces@lists.teslaclub.hk" target="_blank">ovmsdev-bounces@lists.teslaclub.hk</a> [mailto:<a href="mailto:ovmsdev-bounces@lists.teslaclub.hk" target="_blank">ovmsdev-bounces@lists.teslaclub.hk</a>] <b>On Behalf Of </b>Mastro Gippo<br>
<b>Sent:</b> 17. juni 2014 00:33<br><b>To:</b> OVMS Developers<br><b>Subject:</b> Re: [Ovmsdev] OVMS - HW</span><u></u><u></u></p><div><div><p class="MsoNormal"> <u></u><u></u></p><div><div><div><div><div><div><p class="MsoNormal">
Hi, this is the correct DS: <a href="http://www.st.com/web/en/resource/technical/document/datasheet/CD00000444.pdf" target="_blank">http://www.st.com/web/en/resource/technical/document/datasheet/CD00000444.pdf</a><u></u><u></u></p>
</div><p class="MsoNormal">for the DPAK package the OVMS is using, you have 8°C/W for the TJ and 100°C/W for TA. (it's a small package!)<u></u><u></u></p></div><p class="MsoNormal">Also, you must calc the dissipation thinking about the "dissipated" voltage, so not 5V but (14V-5V) = 9V (worst case).<u></u><u></u></p>
</div><p class="MsoNormal">You should also add some margin, e.g. use 100mA instead of 80mA just to be safe.<u></u><u></u></p></div><p class="MsoNormal">Just try it and keep a finger on the IC for a few minutes to see if it overheats, it shouldn't hurt the board.<u></u><u></u></p>
</div><div><p class="MsoNormal"> <u></u><u></u></p></div><p class="MsoNormal">MG<u></u><u></u></p></div><div><p class="MsoNormal" style="margin-bottom:12.0pt"> <u></u><u></u></p><div><p class="MsoNormal">2014-06-17 0:14 GMT+02:00 Olav A. Antonsen <<a href="mailto:olav@ansit.no" target="_blank">olav@ansit.no</a>>:<u></u><u></u></p>
<blockquote style="border:none;border-left:solid #cccccc 1.0pt;padding:0cm 0cm 0cm 6.0pt;margin-left:4.8pt;margin-top:5.0pt;margin-right:0cm;margin-bottom:5.0pt"><div><div><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Great video thermal design.</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">My knowledge on thermal design is only 30 minutes old, but my interpretation of the datasheet gives med</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">The regulator will reach 23°C/W above ambient. </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Running at max 1.5A @ 5V =  7.5W.</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">23C/W => 172.5°C -> To hot to handle</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">2 relays @ 80mA each ~ 0.16A @ 5V ~ 0,8W ~ 18.4°C above ambient. </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">My conclusion is that adding a consumption of 160mA will raise the temperature 18.4°C above ambient. (This comes in addition to the current the OVMS module consumes.</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">)</span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Is this correct?</span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Regards</span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Olav</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p>
<div style="border:none;border-top:solid #b5c4df 1.0pt;padding:3.0pt 0cm 0cm 0cm"><p class="MsoNormal"><b><span lang="NO-BOK" style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">Fra:</span></b><span lang="NO-BOK" style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> <a href="mailto:ovmsdev-bounces@lists.teslaclub.hk" target="_blank">ovmsdev-bounces@lists.teslaclub.hk</a> [mailto:<a href="mailto:ovmsdev-bounces@lists.teslaclub.hk" target="_blank">ovmsdev-bounces@lists.teslaclub.hk</a>] <b>På vegne av</b> Mastro Gippo<br>
<b>Sendt:</b> 16. juni 2014 23:38</span><u></u><u></u></p><div><div><p class="MsoNormal"><span lang="NO-BOK"><br><b>Til:</b> OVMS Developers<br><b>Emne:</b> Re: [Ovmsdev] OVMS - HW</span><u></u><u></u></p></div></div></div>
<div><div><p class="MsoNormal"><span lang="NO-BOK"> </span><u></u><u></u></p><div><div><div><div><div><div><p class="MsoNormal"><span lang="NO-BOK">The 1.5A is not the whole story; you can watch this: <a href="https://www.youtube.com/watch?v=8ruFVmxf0zs" target="_blank">https://www.youtube.com/watch?v=8ruFVmxf0zs</a></span><u></u><u></u></p>
</div><p class="MsoNormal"><span lang="NO-BOK">Basically, if you had that 7805 on free air powering your two relays, it would (try to) reach about 170°C above ambient temperature. The PCB is a nice heatsink, but it is shared with the big GSM regulator, and that rises the temperature too.</span><u></u><u></u></p>
</div><p class="MsoNormal"><span lang="NO-BOK">By all means, experiment!! The 7805 has thermal protection, and you should test your circuit on the bench keeping a finger on the IC to feel if it gets too hot.</span><u></u><u></u></p>
</div><p class="MsoNormal" style="margin-bottom:12.0pt"><span lang="NO-BOK">You should take care of the increased ripple too, but a small cap should do the trick there.</span><u></u><u></u></p></div><p class="MsoNormal"><span lang="NO-BOK">Regards</span><u></u><u></u></p>
</div><p class="MsoNormal"><span lang="NO-BOK">MG</span><u></u><u></u></p></div><div><p class="MsoNormal" style="margin-bottom:12.0pt"><span lang="NO-BOK"> </span><u></u><u></u></p><div><p class="MsoNormal"><span lang="NO-BOK">2014-06-16 23:09 GMT+02:00 Olav A. Antonsen <<a href="mailto:olav@ansit.no" target="_blank">olav@ansit.no</a>>:</span><u></u><u></u></p>
<div><div><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">I got some help from a user on a Norwegian forum who pointed me to </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><a href="https://raw.githubusercontent.com/openvehicles/Open-Vehicle-Monitoring-System/master/vehicle/Car%20Module/v2-base/OVMS_V6A.pdf" target="_blank"><span style="color:#1f497d;text-decoration:none">https://raw.githubusercontent.com/openvehicles/Open-Vehicle-Monitoring-System/master/vehicle/Car%20Module/v2-base/OVMS_V6A.pdf</span></a></span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Looks like a 7805-regulator is supplying the OVMS module with +5V @ 1.5A max.</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><a href="https://www.sparkfun.com/datasheets/Components/LM7805.pdf" target="_blank">https://www.sparkfun.com/datasheets/Components/LM7805.pdf</a></span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">80mA won't be a problem then.</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">--Olav</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p><div style="border:none;border-top:solid #b5c4df 1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span lang="NO-BOK" style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">Fra:</span></b><span lang="NO-BOK" style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> <a href="mailto:ovmsdev-bounces@lists.teslaclub.hk" target="_blank">ovmsdev-bounces@lists.teslaclub.hk</a> [mailto:<a href="mailto:ovmsdev-bounces@lists.teslaclub.hk" target="_blank">ovmsdev-bounces@lists.teslaclub.hk</a>] <b>På vegne av</b> Mastro Gippo<br>
<b>Sendt:</b> 16. juni 2014 23:03<br><b>Til:</b> OVMS Developers<br><b>Emne:</b> Re: [Ovmsdev] OVMS - HW</span><u></u><u></u></p></div><div><div><p class="MsoNormal"><span lang="NO-BOK"> </span><u></u><u></u></p><div><div>
<p class="MsoNormal"><span lang="NO-BOK">It may be a problem to get the 5V from the output of the regulator, but the nice thing about that module is that it is isolated; you can connect your own power supply and be 100% safe. These relays draw about 80mA each (just tested them, I have the same product at home), so if you turn them on one at a time and for short periods of time it should be ok (I don't know a lot about the termal design of the OVMS).</span><u></u><u></u></p>
</div><p class="MsoNormal"><span lang="NO-BOK">MG</span><u></u><u></u></p></div><div><p class="MsoNormal" style="margin-bottom:12.0pt"><span lang="NO-BOK"> </span><u></u><u></u></p><div><p class="MsoNormal"><span lang="NO-BOK">2014-06-16 22:37 GMT+02:00 Olav A. Antonsen <<a href="mailto:olav@ansit.no" target="_blank">olav@ansit.no</a>>:</span><u></u><u></u></p>
<div><div><div><p class="MsoNormal"><span lang="NO-BOK" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Hello</span><u></u><u></u></p><p class="MsoNormal"><span lang="NO-BOK" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">My knowledge of electronics is limited.</span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">As far as I understand the OVMS module is supplied with +12V via the OBD connector. What I don't understand is where the +5V comes from? </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><a href="https://github.com/openvehicles/Open-Vehicle-Monitoring-System/blob/master/vehicle/Car%20Module/v2-base/20120814-boarddesign.pdf" target="_blank">https://github.com/openvehicles/Open-Vehicle-Monitoring-System/blob/master/vehicle/Car%20Module/v2-base/20120814-boarddesign.pdf</a></span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">I'm currently trying to control a relay using the RC3 output on the PIC18F2580 as a control signal to a rely on a relay module</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><a href="http://www.dx.com/p/arduino-2-channel-relay-shield-module-red-144140#.U59Qavl_t8E" target="_blank">http://www.dx.com/p/arduino-2-channel-relay-shield-module-red-144140#.U59Qavl_t8E</a>.</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">The relay module needs to be supplied with +5V to drive the relays, and my plan was to get the +5V from the OVMS module using pin 13 on the HEADER 9X2.</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">But I'm afraid I might blow something on the OVMS module if the relay module draws to many mA.</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Any advice would be appreciated.</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">--Olav</span><u></u><u></u></p>
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