Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

[PIC] PIC16F73 Buck converter design problem

Status
Not open for further replies.

anand78pankaj

Newbie level 2
Joined
Aug 10, 2015
Messages
2
Helped
0
Reputation
0
Reaction score
0
Trophy points
1
Activity points
16
Dear all, I am facing problem in designing buck converter. I have successfully tested my code written in assem. language in logic analyzer. The PWM Freq. is 100 Khz.

The problem is i am not getting reduced voltage as per duty cycle at the output. Please suggest.
 

FvM

Super Moderator
Staff member
Joined
Jan 22, 2008
Messages
48,365
Helped
14,245
Reputation
28,751
Reaction score
12,931
Trophy points
1,393
Location
Bochum, Germany
Activity points
279,954
Show your circuit.

Do you know that the output voltage will be proportional to duty cycle only in continuous conduction mode (CCM) of the buck converter, in other words with sufficient load current?
 

anand78pankaj

Newbie level 2
Joined
Aug 10, 2015
Messages
2
Helped
0
Reputation
0
Reaction score
0
Trophy points
1
Activity points
16
I have attached the circuit for your kind perusal. What I have noticed is, when I give only high or low command to Pin RC2 one by one, the Power MOSFET works well and load cuts off. But, when i give PWM than Power Mosfet remains always On.
The Voltage at the Gate of M2 remains at 3.36 Volt approx.

https://obrazki.elektroda.pl/5898832800_1439388664.jpg
 

Attachments

  • Buck converter_1.jpg
    Buck converter_1.jpg
    719.2 KB · Views: 16

Najmul_I

Newbie level 2
Joined
Aug 13, 2015
Messages
2
Helped
0
Reputation
0
Reaction score
0
Trophy points
1
Activity points
11
you should reduce the Gate-Source resistance(100k) of M2. Because the gate-source capacitor need to be discharge. you could use 100 ohm.
 

HULK28

Newbie level 3
Joined
Jul 4, 2015
Messages
4
Helped
0
Reputation
0
Reaction score
0
Trophy points
1
Location
France
Activity points
38
buck_PMOS_driver.jpgHello,

have you some references for M1 and M2? It's easier for validate your application ;)
Be careful, you must also protect gate-source of M1 (VGS(max) is generally 20V for absolute maximum rating) with a zener (15V) and a 220 resistor in M2 drain, because your solar panel, i suppose a 12V model with OCV at 22V, can reach over this 20V rating and transistor will break down...
Here an exemple for your need with some add features for high speed.
Regards.
JY
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top