DC converter
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From: john on 18 Feb 2010 15:16 Hi, I am using the following function generator to produce a 60Hz , 16Volts peak to peak output voltage. http://www.globaltestsupply.com/datasheets/4011a.pdf I am using following DC to DC converter and Bridge Rectifier http://cds.linear.com/docs/Datasheet/3970f.pdf http://www.diodes.com/datasheets/ds17002.pdf The bridge rectifier is hooked up to the function generator and the output of the bridge rectifier is going to the DC to DC Converter's pin 3. I am using the ciruit as given on the first page of the data sheet except I used two capacitors in parallel instead of 2.2uF , 50 volts 10uF and 1uf 50v capacitor at the input input Vin. So, if the input voltage is 16 volts peak to peak , then after the bridge I get nearly 6 volts (measured by scope) at the output of the bridge and I get 3.6 volts (measured by voltmeter) at the output of the DC to DC converter. The DC TO DC converter suppose to output 5 volts. but it is outputting 3.7 volts. I am unable to understand what is the problem. I hooked up the DC to DC converter to the power supply and it produced 5 volts but with bridge rectifier, it is not producing the appropiate voltage. Am I using the wrong capacitor values? Please advise! John
From: Joerg on 18 Feb 2010 15:43 john wrote: > Hi, > > I am using the following function generator to produce a 60Hz , > 16Volts peak to peak output voltage. > > http://www.globaltestsupply.com/datasheets/4011a.pdf > > I am using following DC to DC converter and Bridge Rectifier > > http://cds.linear.com/docs/Datasheet/3970f.pdf > > http://www.diodes.com/datasheets/ds17002.pdf > > The bridge rectifier is hooked up to the function generator and the > output of the bridge rectifier is going to the DC to DC Converter's > pin 3. I am using the ciruit as given on the first page of the data > sheet except I used two capacitors in parallel instead of 2.2uF , 50 > volts 10uF and 1uf 50v capacitor at the input input Vin. > > So, if the input voltage is 16 volts peak to peak , then after the > bridge I get nearly 6 volts (measured by scope) at the output of the > bridge and I get 3.6 volts (measured by voltmeter) at the output of > the DC to DC converter. > How does that 6V look? Lots of ripple? Depending on your load current 60Hz requires a few hundred uF. So if other than the 10uF there's nothing on the input side that would be your problem :-) > The DC TO DC converter suppose to output 5 volts. but it is outputting > 3.7 volts. I am unable to understand what is the problem. I hooked up > the DC to DC converter to the power supply and it produced 5 volts but > with bridge rectifier, it is not producing the appropiate voltage. Am > I using the wrong capacitor values? Please advise! > > John -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Jan Panteltje on 18 Feb 2010 15:46 On a sunny day (Thu, 18 Feb 2010 12:16:57 -0800 (PST)) it happened john <conphiloso(a)hotmail.com> wrote in <1a3bf241-c904-4dbc-9475-c5f71785f329(a)g23g2000vbl.googlegroups.com>: >Hi, > >I am using the following function generator to produce a 60Hz , >16Volts peak to peak output voltage. > >http://www.globaltestsupply.com/datasheets/4011a.pdf > >I am using following DC to DC converter and Bridge Rectifier > >http://cds.linear.com/docs/Datasheet/3970f.pdf > >http://www.diodes.com/datasheets/ds17002.pdf > >The bridge rectifier is hooked up to the function generator and the >output of the bridge rectifier is going to the DC to DC Converter's >pin 3. I am using the ciruit as given on the first page of the data >sheet except I used two capacitors in parallel instead of 2.2uF , 50 >volts 10uF and 1uf 50v capacitor at the input input Vin. > > So, if the input voltage is 16 volts peak to peak , then after the >bridge I get nearly 6 volts (measured by scope) at the output of the >bridge and I get 3.6 volts (measured by voltmeter) at the output of >the DC to DC converter. > >The DC TO DC converter suppose to output 5 volts. but it is outputting >3.7 volts. I am unable to understand what is the problem. I hooked up >the DC to DC converter to the power supply and it produced 5 volts but >with bridge rectifier, it is not producing the appropiate voltage. Am >I using the wrong capacitor values? Please advise! > >John Without looking at your diagram, did you take into account the voltage drop of 2 diodes in the bridge? 2 x 0.7 = 1.4 5 - 1.4 = 3.6
From: Jon Kirwan on 18 Feb 2010 15:49 On Thu, 18 Feb 2010 12:16:57 -0800 (PST), john <conphiloso(a)hotmail.com> wrote: >The bridge rectifier is hooked up to the function generator and the >output of the bridge rectifier is going to the DC to DC Converter's >pin 3. A function generator is _feeding_ the bridge? Jon
From: john on 18 Feb 2010 16:15
Hi, Yes the function generator is feeding the bridge. I increased the input voltage frequency upto 5000Hz and 50khz and amplitude to 24 volts peak to peak. And also took the full bridge out and replace with one diode and connect a 20kohm as a load and 220uF 25 volts capacitor in parallel with the load. I can see the output of 9 volts (volt meter mesurement) So, now I have half bridge rectifier output but still I am not getting the 5 volts output. As soon as I connect the output of the single diode bridge to the DC to DC converter the output of the single diode bridge falls from 9 volts to 3.5 volts and the out put of the DC to DC converter is 3.5 volts not 5 volts. The ground of the fumction generator is connected to ground of the dc to dc converter John |