Dc-Dc Buck converter

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VCC is the low-side supply and should be between 10V and 20V. VDD is the logic supply to the IR2110. It can be between +3V to +20V (with reference to VSS). The actual voltage you choose to use depends on the voltage level of your input signals.

A bootstrap circuitry (diode + capacitor) – utilizing VCC, VB and VS – is used to provide the floating supply to drive the MOSFET. When high, the level on HO is equal to the level on VB, with respect to VS. When low, the level on HO is equal to VS - can be assumed to be zero.

Hope this helps.
Tahmid.
 


sure it help
but if i use only high side should i connect Vcc or not and Lo connect it to ground or leave it
 

Yes you should connect VCC. Connect a diode between VCC and VB. This is the bootstrap diode. The bootstrap capacitor is connected between VB and VS.

For high side only, you don't need to use LO. Connect LIN to ground.

Hope this helps.
Tahmid.
 

Tahmid said:
Yes you should connect VCC. Connect a diode between VCC and VB. This is the bootstrap diode. The bootstrap capacitor is connected between VB and VS.

For high side only, you don't need to use LO. Connect LIN to ground.

Hope this helps.
Tahmid.
Click to expand...

thanks alot
it work great but there is some small problems :
1-for my calculation capacitor is 20 uf
if i use cap like 47 uf is got hot and burnt and out put has alot of ripple
but if i use 3000 uf (3 cap 1000 in parallel) i got lettle ripple.

2-what current shoult i design my circuit for max current or average current ( for low current load output voltage was high than desing)

3- sould i use high inductor than calculation ( high up to ???)
 

i need away to isolate between microcontroller and circuit >>> i have on source so one ground of all circuit so i can't use optocoupler
 

you dont need isolation you have problem of microcontroller powersupply



(1) connect an external power supply to microcontroller to varify that microcontroller is restarting because of its powersupply.

(2) find out that is it really going restart ? (connect mcu with pc via rs232 and contenusely send present status of microcontroller or any other procedure to find out that it is really going restart ) .



simply find out your real problem and then find solution.
if problem is noise of powersupply then it shuld be work well on external powersupply.
 


already i send value of output voltage on serial and micro restart when i connect it to the same supply of the circuit
 

Applying heavy switching loades to a battery or unregulated DC sources.
It makes noise in battery voltages or unregulated DC sources.
Switching load means a load which is oscillating for example inverter circuit.
Your project is using oscillator which is making on/off mosfet switch.
That's why your power supply becomes noisey.

1) Use capicitors to parallel of your DC source.
2) Use a diod to the input of LM 2576.
3) Also Use thick wires in power section for wiring to avoid noise.
(thin wires are also a major source of power supply noise)
 

thanks for every one helped me,
i reach a good level of my circuit design
i have 2 problems :
1- how can i achieve constanst voltage at no load like lm2576 switch mode regulator
2- when motor start alot of noise appear at chooper output and it become difficult to achieve desired voltage as fast as any other load rather than motor., how can i eliminate motor noise?
 

1
switch mode power supply (smps) shuld not be operated without load. you shuld always connect a dummy load to the output of smps.
Resistor is best choice for dummy load . a few hundred milliampares shuld always flow through output. this will maintain output voltages
before connecting your load.
2
you can compress motor noise by connecting reverse diode to parallel of motor supply.
connect non polar high voltages capacitors to parallel to motor to avoide inductive kickback.
 


please give me a schematic of connecting diode ? i try motor with my h-bridge circuit what have four diode but have no effect?
 

i think you are rotating motor forward and reverse either you are driveing ac motor
if i am right then you can not connect diode to parallel to motor .
only connect high voltage nonpolar capacitores to parallel of motor and h bridge input . for example 0.1uf 400v
 

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