(Created page with "Right now there usually are numerous methods employed inside natural flea control. Hand picking is fairly powerful. Every time a dog comes throughout from outdoors, immediatel...")
 
(LTC3780 High Efficiency, Synchronous Buck Boost DC-DC Converter)
 
(5 intermediate revisions by one user not shown)
Line 1: Line 1:
Right now there usually are numerous methods employed inside natural flea control. Hand picking is fairly powerful. Every time a dog comes throughout from outdoors, immediately run a narrow toothed flea comb over him and also wash the critters down the actual drain. This particular is time consuming should you live in a multidog household, but fortunately right now there usually are alternative methods. Fleas reside on vegetation within the outdoors. Adding kelp to be able to the actual soil assists plants develop their own arsenal against pests. Kelp typically is a important and also undervalued defensive weapon. When composted within the soil it adds numerous nutrients and plant enzymes which act as preventative against insect pests.
+
 
Several of us prefer to totally prevent the actual employ of toxins with regard to our dwelling, not to mention particularly on our pets. Luckily, there are generally countless natural flea control methods that you can buy. Indeed there is a lot of inaccurate information and facts circulating about the particular Web regarding flea control for pets not to mention natural flea control treatments such as neem. Various individuals currently have heard of neem oil yet don't actually grasp a lot with regards to it or simply just how that would use it safely with pets.
+
== LTC3780 High Efficiency, Synchronous Buck Boost DC-DC Converter ==
The particular at first thing to realize about natural flea control remedies, typically is that merely because something is purely natural, does certainly not mean it's certainly not toxic. Pyrethrins, insecticides derived within the African chrysanthemum, tend to be both purely natural and even toxic.
+
 
Important essential oils
+
Prevalent on ebay and Amazon is the [http://www.ebay.com/sch/LTC3780+Automatic+lifting+pressure "LTC3780 Automatic lifting pressure constant voltage step up step down 10A 130W"] DC to DC Converter. (What a mouthful)
A bunch of important oils is toxic with regard to large doses because well, particularly that would cats. Since cats never metabolize important oils terribly well, they could certainly develop up inside their systems not to mention cause issues. Even though numerous cat owners make use of natural flea control remedies which contain necessary essential oils, it really is advisable that would incorporate caution.
+
 
Good nutrition and also flea control
+
I'm not quite sure what the "Automatic lifting pressure" is about (suspect Chinglish), but it is a fairly well designed DC-DC switcher based on Linear's [http://www.linear.com/product/LTC3780 LTC3780 - High Efficiency, Synchronous, 4-Switch Buck-Boost Controller]. The board sells for a bargain basement price of about $20 to $25 USD.
Feeding a pet advantageous top quality food typically is not just the particular proper thing to do, it could equally provide greater protection against fleas. Poor nutrition can create your pet more susceptible to be able to fleas, since a healthy animal typically is less attractive to be able to adult fleas. Ask the vet for recommendations.
+
 
Garlic as well as yeast
+
<center>http://wiki.beyondlogic.org/i/LTC3780_WD2002SJ.jpg</center>
Bother garlic and yeast can easily assist to obviously protect your own pet from fleas. Cat owners ought to be aware, but bear in mind, that garlic is actually toxic to cats, and even can damage their red blood cells.
+
 
Brewer's yeast can be utilized for both dogs as well as pets. Make full use of regarding 1 teaspoon for pets not to mention small dogs, plus about a tablespoon for a fifty pound dog. If perhaps your individual pet develops a skin rash, they may be allergic to be able to yeast
+
My interest in this DC-DC switcher is to operate 19VDC laptops/notebooks and LCD TVs from 12V batteries/solar.
Control Your own Environment: Should you remain capable that would let your own pet inside the actual apartment, it can lessen the risk of having fleas with your pets. The particular more they may go outside, more possibilities are to be able to get more fleas. Pretty much, your pet gets the flea from other animals outside, thus avoid your individual pet contact with outside animals. Anyone could moreover bring a modern product, which are really specially crafted to be able to kill fleas.
+
 
Grooming/Bathing: you will need to comb the pet on regular basis and also trim it's hair. It usually also minimize the particular risk of presence of fleas and also you will easily control fleas.
+
I took the plunge and purchased two units. Here are the specifications:
Prior to adopting the actual proper measures for killing the actual fleas from the home, anyone could recognize the actual basic knowledge with regards to fleas. We should really keep within mind which weather cannot affect fleas. They do not become less in winter somewhat they survive with regard to the coldest weather as well. They may live inside the deep freezer too. Thus anyone ought to consume strong measures for natural flea control.
+
 
Among the many very best resources to attain more information on natural flea control is actually [http://www.carpetfleas.com/remedies-for-natural-and-orangic-flea-control/ Natural Flea Control]
+
* Input Voltage: 5-32V DC.
 +
* Output Voltage: 1-30V DC via trimpot.
 +
* Output Current: 10A maximum, 7A continuous.
 +
* Output Power: 80W continuous, peak 130W.
 +
* Input Fused: 15A; removable SMD fuse.
 +
* Short Circuit Protected.
 +
* Low Voltage Disconnect.
 +
* Size 77.6 (if snapped at V-Groove) x 46.5 x 15mm.
 +
 
 +
You will notice there are three trimpots and an absence of documentation. Well that's not quite true, I did find the [http://wiki.beyondlogic.org/downloads/LTC3780_WD2002SJ_DataSheet.pdf product datasheet] if you can read Chinese.
 +
 
 +
Upon delivery, it was evident one unit was touched up on the production line. There was residual flux around the LTC3780, and in the process of touching up the joints, one of the trimpots were inadvertently burnt.
 +
 
 +
Pushing ahead, the next task was to connect the new arrivals to a bench power supply and DC load and put them through their paces.  
 +
 
 +
During testing of the adjustable current limiting, I fried one of the boards. No output, just the red fault LED steadily illuminated. Whoops.
 +
 
 +
The next stage was to investigate the cause. In doing so, I sketched out the following schematics of the supervisory components of the DC-DC switcher.
 +
 
 +
=== Supervisory Circuit Operation ===
 +
 
 +
The low voltage disconnect/cut-off and adjustable current limit is controlled by a commodity LM358 Dual Operational Amplifier running from a 5 volt rail generated by a LM7805 linear regulator. 
 +
 
 +
<center>http://wiki.beyondlogic.org/i/LTC3780_WD2002SJ_Regulator.jpg</center>
 +
 
 +
The red Fault LED is connected to the LTC3780 power good (PG) output. According to the LTC3780 data sheet, the PG output is pulled low when the output voltage is outside +/- 7.5% of the regulation point.  
 +
 
 +
<center>http://wiki.beyondlogic.org/i/LTC3780_WD2002SJ_LowVoltageCutout.jpg</center>
 +
 
 +
The low voltage disconnect/cut-off consists of a comparator circuit connected to the run pin of the LTC3780. When 'run' is below 1.5V, the LTC3780 shuts down. The data sheet warns not to apply greater than 6V to this pin.
 +
 
 +
The LM358's output is not rail to rail. At best, according to the data sheet, the maximum output is VCC - 1.5V. In normal operation Vout/run sits at about 3.6V.
 +
 
 +
The VIN voltage divider is compared to a 2.5V reference. The VIN voltage divider, consisting of a 500k trimmer and 36K resistor allows a low voltage cutout in the range of 2.5V to 37V, exceeding both the minimum and maximum  input voltage. There appears to be no hysteresis and this is evident in testing.
 +
 
 +
<center>http://wiki.beyondlogic.org/i/LTC3780_WD2002SJ_AdjustableCurrentLimit.jpg</center>
 +
 
 +
VR3 and R9 makes up the external voltage divider for the error amplifier feedback input. The LTC3780 will adjust the output to ensure the voltage on VOsense is 0.800V. VOut can be calculated by 0.8V * (1 + R2/R1). The 500k trimmer and 14k resistor gives an output voltage range of 0.8V to 29V.
 +
 
 +
The adjustable over current protection consists of a non-inverting amplifier that pulls VOsense above 0.8V in the event of an over current condition. This causes the LTC3780 to back off, dropping the output voltage.
 +
 
 +
The non-inverting amplifier has a gain of 9 to 1801. With a 7mOhm current shunt, and ignoring the forward voltage drop of the diode, a range of 70mA to 13A can be expected. In practice, the minimum current sense is about 160mA.
 +
 
 +
=== Fault finding ===
 +
 
 +
On my now faulty unit, the 5V supply rail was reading 8.95V. Worst still, I had 7V feeding the run pin when the chip manufacturer warned not to exceed 6V.
 +
 
 +
My first thought was the LM358 was causing this. Removal of the part, confirmed this, and my 5V rail returned back to a more comfortable 5V.
 +
 
 +
But still no go. Looking at the data sheet, the LTC3780 has an internal 100k pull down resistor on the run pin, plus the board has a 10k to ground, both working to disable the switcher. I proceeded to solder a 10k resistor (only needed to bring run over 1.5V) between pins 7 and 8 where the LM358 once lived.  
 +
 
 +
The run pin was now at 2.5V, but no go. It was now almost certain that exceeding 6V fried the run pin. I placed a new LTC3780IUH#PBF on order.  
 +
 
 +
Once the new LTC3780 arrived, using hot air, I swapped it over and with my 'run' pull-up resistor still fitted, my board sprung to life. I've since soldered a 0603 resistor between pads 7 and 8 where the LM358 once stood.

Latest revision as of 10:13, 30 June 2015

LTC3780 High Efficiency, Synchronous Buck Boost DC-DC Converter

Prevalent on ebay and Amazon is the "LTC3780 Automatic lifting pressure constant voltage step up step down 10A 130W" DC to DC Converter. (What a mouthful)

I'm not quite sure what the "Automatic lifting pressure" is about (suspect Chinglish), but it is a fairly well designed DC-DC switcher based on Linear's LTC3780 - High Efficiency, Synchronous, 4-Switch Buck-Boost Controller. The board sells for a bargain basement price of about $20 to $25 USD.

LTC3780_WD2002SJ.jpg

My interest in this DC-DC switcher is to operate 19VDC laptops/notebooks and LCD TVs from 12V batteries/solar.

I took the plunge and purchased two units. Here are the specifications:

  • Input Voltage: 5-32V DC.
  • Output Voltage: 1-30V DC via trimpot.
  • Output Current: 10A maximum, 7A continuous.
  • Output Power: 80W continuous, peak 130W.
  • Input Fused: 15A; removable SMD fuse.
  • Short Circuit Protected.
  • Low Voltage Disconnect.
  • Size 77.6 (if snapped at V-Groove) x 46.5 x 15mm.

You will notice there are three trimpots and an absence of documentation. Well that's not quite true, I did find the product datasheet if you can read Chinese.

Upon delivery, it was evident one unit was touched up on the production line. There was residual flux around the LTC3780, and in the process of touching up the joints, one of the trimpots were inadvertently burnt.

Pushing ahead, the next task was to connect the new arrivals to a bench power supply and DC load and put them through their paces.

During testing of the adjustable current limiting, I fried one of the boards. No output, just the red fault LED steadily illuminated. Whoops.

The next stage was to investigate the cause. In doing so, I sketched out the following schematics of the supervisory components of the DC-DC switcher.

Supervisory Circuit Operation

The low voltage disconnect/cut-off and adjustable current limit is controlled by a commodity LM358 Dual Operational Amplifier running from a 5 volt rail generated by a LM7805 linear regulator.

LTC3780_WD2002SJ_Regulator.jpg

The red Fault LED is connected to the LTC3780 power good (PG) output. According to the LTC3780 data sheet, the PG output is pulled low when the output voltage is outside +/- 7.5% of the regulation point.

LTC3780_WD2002SJ_LowVoltageCutout.jpg

The low voltage disconnect/cut-off consists of a comparator circuit connected to the run pin of the LTC3780. When 'run' is below 1.5V, the LTC3780 shuts down. The data sheet warns not to apply greater than 6V to this pin.

The LM358's output is not rail to rail. At best, according to the data sheet, the maximum output is VCC - 1.5V. In normal operation Vout/run sits at about 3.6V.

The VIN voltage divider is compared to a 2.5V reference. The VIN voltage divider, consisting of a 500k trimmer and 36K resistor allows a low voltage cutout in the range of 2.5V to 37V, exceeding both the minimum and maximum input voltage. There appears to be no hysteresis and this is evident in testing.

LTC3780_WD2002SJ_AdjustableCurrentLimit.jpg

VR3 and R9 makes up the external voltage divider for the error amplifier feedback input. The LTC3780 will adjust the output to ensure the voltage on VOsense is 0.800V. VOut can be calculated by 0.8V * (1 + R2/R1). The 500k trimmer and 14k resistor gives an output voltage range of 0.8V to 29V.

The adjustable over current protection consists of a non-inverting amplifier that pulls VOsense above 0.8V in the event of an over current condition. This causes the LTC3780 to back off, dropping the output voltage.

The non-inverting amplifier has a gain of 9 to 1801. With a 7mOhm current shunt, and ignoring the forward voltage drop of the diode, a range of 70mA to 13A can be expected. In practice, the minimum current sense is about 160mA.

Fault finding

On my now faulty unit, the 5V supply rail was reading 8.95V. Worst still, I had 7V feeding the run pin when the chip manufacturer warned not to exceed 6V.

My first thought was the LM358 was causing this. Removal of the part, confirmed this, and my 5V rail returned back to a more comfortable 5V.

But still no go. Looking at the data sheet, the LTC3780 has an internal 100k pull down resistor on the run pin, plus the board has a 10k to ground, both working to disable the switcher. I proceeded to solder a 10k resistor (only needed to bring run over 1.5V) between pins 7 and 8 where the LM358 once lived.

The run pin was now at 2.5V, but no go. It was now almost certain that exceeding 6V fried the run pin. I placed a new LTC3780IUH#PBF on order.

Once the new LTC3780 arrived, using hot air, I swapped it over and with my 'run' pull-up resistor still fitted, my board sprung to life. I've since soldered a 0603 resistor between pads 7 and 8 where the LM358 once stood.