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Noob to the forum
- Thread starter Dr pepper
- Start date
Thanks.
Yes a little in smps applications, and a fair bit in motor control.
I built a nixie clock, ht for the tubes came from a switching supply controlled from the pic16f628a, it was a simple feedbackless loop, brightness was adjustable in software, all the pic did though was generate a variable pulse width, no feedback.
This has been done using something like a pic16f88 using an analogue channel as feedback, this can get real ugly with the control algorithm when you start thinking about things like compensation.
Do you want to build a smps using just a pic and discretes, or do you want to be able to control a smps chip using a micro, the latter is a more practical approach unless your mass producing something and really need to cut costs.
Yes a little in smps applications, and a fair bit in motor control.
I built a nixie clock, ht for the tubes came from a switching supply controlled from the pic16f628a, it was a simple feedbackless loop, brightness was adjustable in software, all the pic did though was generate a variable pulse width, no feedback.
This has been done using something like a pic16f88 using an analogue channel as feedback, this can get real ugly with the control algorithm when you start thinking about things like compensation.
Do you want to build a smps using just a pic and discretes, or do you want to be able to control a smps chip using a micro, the latter is a more practical approach unless your mass producing something and really need to cut costs.
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@Dr pepper;
Welcome!
@demykiko;
Re: your other thread about MCU SMPS:
this. +1.
Analog control loop adjusted with a DAC or digipot all the way.
Welcome!
@demykiko;
Re: your other thread about MCU SMPS:
this. +1.
...it was a simple feedbackless loop...
...this can get real ugly with the control algorithm when you start thinking about things like compensation.
Do you want to build a smps using just a pic and discretes, or do you want to be able to control a smps chip using a micro, the latter is a more practical approach...
Analog control loop adjusted with a DAC or digipot all the way.
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I'm glad to know that you had successful smps using MCU particularly the pic16f628a..for your information I'm currently doing an smps design using a MCU also
but rather based on Attiny85..Even a feedback less is ok for the meantime, just to make it simple...My target purpose is to have an SMPS with variable output voltage, gradually and manually adjustable via two tact switches..one for increase the other for decrease..I hope for the support from you if you have time..because
I'm still a newwbie to MCU programming...by the way I have a question if you use Lo-Hi side driver IC like IR2110, IR2113 or a GDT for MOSFET & IGBT and BDT for BJT?
Regards KX36..
but rather based on Attiny85..Even a feedback less is ok for the meantime, just to make it simple...My target purpose is to have an SMPS with variable output voltage, gradually and manually adjustable via two tact switches..one for increase the other for decrease..I hope for the support from you if you have time..because
I'm still a newwbie to MCU programming...by the way I have a question if you use Lo-Hi side driver IC like IR2110, IR2113 or a GDT for MOSFET & IGBT and BDT for BJT?
Regards KX36..
I just did one with a GDT. Took a couple of days to debug a delayed and slow rise time during which time I was wishing I'd used an IR2110. In the end the problem was an over-complicated transistor driver which was saturating and taking too long for currents to circulate through it to desaturate it, so I can't blame the GDT for that. It would have been much beter if my controller IC had complementary outputs but this one is single ended.
There are pros and cons to each. The GDT generally can drive less current through its impedance and any coupling capacitors and damping resistors. It also transmits an AC signal so duty cycle affects the peak and trough voltages. You can use a "DC recovery circuit" after a GDT but you add the risk of ringing or shoot-through under certain conditions such as at shutdown or if the input to the GDT goes high impedance, IIRC. GDT also generally takes more PCB area than a SOIC or TSSOP footprint driver IC but doesn't need to be anywhere near as massive as you often see around here, but it is significantly cheaper and done right very reliable. I have heard it quoted that SMPS guru Dr Ray Ridley is GDT over driver IC all the way.
In short, I tend do direct drive low side FETs where possible (single switch flyback, single switch forward, push-pull, boost etc.) but I'd happily use either method for different power supplies.
With regards to driving IGBT or BJT, I wouldn't know. I haven't done anything in the multiple kW power range to justify IGBT over FET and I haven't used a BJT as a primary switch as this isn't the 1970s.
Regards,
Matt
There are pros and cons to each. The GDT generally can drive less current through its impedance and any coupling capacitors and damping resistors. It also transmits an AC signal so duty cycle affects the peak and trough voltages. You can use a "DC recovery circuit" after a GDT but you add the risk of ringing or shoot-through under certain conditions such as at shutdown or if the input to the GDT goes high impedance, IIRC. GDT also generally takes more PCB area than a SOIC or TSSOP footprint driver IC but doesn't need to be anywhere near as massive as you often see around here, but it is significantly cheaper and done right very reliable. I have heard it quoted that SMPS guru Dr Ray Ridley is GDT over driver IC all the way.
In short, I tend do direct drive low side FETs where possible (single switch flyback, single switch forward, push-pull, boost etc.) but I'd happily use either method for different power supplies.
With regards to driving IGBT or BJT, I wouldn't know. I haven't done anything in the multiple kW power range to justify IGBT over FET and I haven't used a BJT as a primary switch as this isn't the 1970s.
Regards,
Matt
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Question answered.
If I was lashing up something I'd use a discrete transistor drive and GDT, only because driver ic's can be critical on board layout and decoupling.
No reason not to implment an smps in software, on a low or midrange ic however unless you use hardware modules the chip wont be able to do a lot else.
I know someone who has put together a couple of succesfull smps welders, and he prefers to handle the smps in a micrcontroller, claiming operation is more predictable.
If I was lashing up something I'd use a discrete transistor drive and GDT, only because driver ic's can be critical on board layout and decoupling.
No reason not to implment an smps in software, on a low or midrange ic however unless you use hardware modules the chip wont be able to do a lot else.
I know someone who has put together a couple of succesfull smps welders, and he prefers to handle the smps in a micrcontroller, claiming operation is more predictable.
Regards to both of you guys for the sharing..It really looks that you have had a deeper knowledge in smps..My first experience was with the use of a driver transformer i.e..GDT..Although it was not perfectly wound (because it was hand-made) but it worked just fine..I was not satisfied with the way GDT give its waveform..In my belief it can not give a clean wave at all because I knew I made it only by my hands..that's why I now switch to using driver IC..and so far,
its waveform is as good as I expected...
Regards,
demykiko
its waveform is as good as I expected...
Regards,
demykiko