Some of my SMPS circuits
Here are a few of the SMPS circuits I made, employing flyback, push-pull, half-bridge and full-bridge topologies.
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Test setup on verroboard of half-bridge SMPS circuit with SG3525 and IR2110 for battery charging. See description below. This is the verroboard prototype of the circuit built on PCB below.
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Offline Half-bridge converter
Input: 160 to 240V AC 50/60Hz
Output: 14.5v 10A (max)
Final test circuit (on PCB) for battery charging. Successful. To be incorporated in SMPS inverter with charger.
The primary side PWM is controlled by SG3525 PWM chip. Frequency of operation is around 50kHz. The output signals of the SG3525 are fed into a IR2110 high-low side driver which drives the 2 MOSFETs (IRF840) configured for half-bridge topology. ETD39 core is used for the transformer. It was wound by hand at home by me. A primary side snubber is used. 2 bulk capacitors (470uF, 200V each) are used for the half-bridge converter.
An auxiliary 50Hz transformer (18V 100mA) is used to provide auxiliary low voltage output, which is rectified, filtered and regulated to 12V with a 7812 to power the SG3525, IR2110 and related circuitry. Since average current is low, voltage difference between 7812 input and output is not too great, the power dissipated by the 7812 is not too high and no heat sink is required.
The output of the ETD39-based transformer is rectified with schottky rectifier STPS3045 and an LC filter is used to filter to pure DC. The output voltage is kept regulated using a zener-optocoupler based voltage feedback loop. The STPS3045 is mounted on a heatsink. The output inductor is the large toroidal inductor beside the 50Hz transformer. It has not been mounted on the PCB.
NTC has been used at the input side to limit inrush current due to charging of the LARGE BULK capacitors at the primary side. A fuse has been used for protection in case of short-circuit.
A 200-ohm resistance is used at the output as "dummy load".
I have designed the PCB myself and have wound the transformer myself, at home.
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1A offline flyback power supply with UC3842
Input: 160 to 240V AC 50/60Hz
Output: 14.5v 1A (max)
Could be used as auxiliary power supply.
The primary side PWM is controlled by UC3842 chip. The UC3842 drives the high voltage MOSFET (IRF840) directly as it has a built-in MOSFET driver. 50k resistor is used for startup from the high voltage DC bus - the UC3842 has built-in zener diode that limits voltage, provided current is low enough.
EE25 core was used for the transformer. I wound the transformer myself.
The output of the transformer is rectified with ultrafast rectifier 31DF6 and capacitor is used to filter to pure DC. The output voltage is kept regulated using a zener-optocoupler based voltage feedback loop.
NTC has been used at the input side to limit inrush current due to charging of the capacitor at the primary side. A fuse has been used for protection in case of short-circuit.
This is one of the oldest SMPS circuits I had made. I made it sometime in 2008.
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2A flyback power supply with TOP-GX
Input: 160 to 240V AC 50/60Hz
Output: 14.5v 2A (max)
The power supply is based on the dedicated offline-switcher "TOPSwitch-GX" TOP245Y, which contains both the primary PWM controller and the high-voltage MOSFET.
EE25 core was used for the transformer. I wound the transformer myself.
The output of the transformer is rectified with ultrafast rectifier MUR420 and LC filter is used to filter to pure DC. The output voltage is kept regulated using a TL431-optocoupler based voltage feedback loop.
NTC has been used at the input side to limit inrush current due to charging of the capacitor at the primary side. A fuse has been used for protection in case of short-circuit.
This is one of the oldest SMPS circuits I had made. I made it sometime in 2008.
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12VDC to 280VDC DC-DC converter for CFL inverter
Input: 11VDC to 14VDC
Output: 280VDC 60W
Was designed to drive four 15W CFL's from 12V battery.
The primary side PWM is controlled by SG3525 PWM chip. Frequency of operation is around 70kHz. The SG3525 drives the 2 MOSFETs (IRF3205) configured for push-pull topology. EI33 core is used for the transformer. It was wound by hand at home by me. The 2 MOSFETs are mounted on heatsinks.
The output of the transformer is rectified to DC with 4 ultrafast diodes (UF4007) configured as a bridge rectifier. LC filter is used to convert output to pure DC.
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Flyback circuit using TOP-GX
Input: 160 to 240V AC 50/60Hz
Output: 12V 3A (max)
The power supply is based on the dedicated offline-switcher "TOPSwitch-GX" TOP245Y, which contains both the primary PWM controller and the high-voltage MOSFET. ETD34 core was used for the transformer. I wound the transformer myself.
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12VDC to 220VAC Inverter (200 to 300W) using SG3525, IR2113 and PIC16F676 with features such as low-battery and overload protection
The primary side PWM is controlled by SG3525 PWM chip. It drives 2 MOSFETs (IRF3205) in push-pull configuration. The MOSFETs drive the transformer. ETD34 core was used for the transformer. The output of the transformer is converted to DC. The high-voltage DC is kept regulated by the SG3525 using direct resistive voltage-divider based feedback. This high-voltage DC is then converted to 50Hz AC using 4 MOSFETs (IRF840) in full-bridge configuration. The quasi-sine signal is generated by the 16F676. The output signals are fed into 2 IR2113 high-low side drivers that drive the MOSFET full-bridge. The 16F676 also monitors the battery voltage for low-voltage cut-out. It also monitors the load current for overload protection.
I made this circuit sometime in 2016 after lots of failure in design and implementation.
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Input: 160 to 240V AC 50/60Hz
Output: 14.5v 10A (max)
Final test circuit (on PCB) for battery charging. Successful. To be incorporated in SMPS inverter with charger.
The primary side PWM is controlled by SG3525 PWM chip. Frequency of operation is around 50kHz. The output signals of the SG3525 are fed into a IR2110 high-low side driver which drives the 2 MOSFETs (IRF840) configured for half-bridge topology. ETD39 core is used for the transformer. It was wound by hand at home by me. A primary side snubber is used. 2 bulk capacitors (470uF, 200V each) are used for the half-bridge converter.
An auxiliary 50Hz transformer (18V 100mA) is used to provide auxiliary low voltage output, which is rectified, filtered and regulated to 12V with a 7812 to power the SG3525, IR2110 and related circuitry. Since average current is low, voltage difference between 7812 input and output is not too great, the power dissipated by the 7812 is not too high and no heat sink is required.
The output of the ETD39-based transformer is rectified with schottky rectifier STPS3045 and an LC filter is used to filter to pure DC. The output voltage is kept regulated using a zener-optocoupler based voltage feedback loop. The STPS3045 is mounted on a heatsink. The output inductor is the large toroidal inductor beside the 50Hz transformer. It has not been mounted on the PCB.
NTC has been used at the input side to limit inrush current due to charging of the LARGE BULK capacitors at the primary side. A fuse has been used for protection in case of short-circuit.
A 200-ohm resistance is used at the output as "dummy load".
I have designed the PCB myself and have wound the transformer myself, at home.
_________________________________________________________________________________________________________________________
1A offline flyback power supply with UC3842
Input: 160 to 240V AC 50/60Hz
Output: 14.5v 1A (max)
Could be used as auxiliary power supply.
The primary side PWM is controlled by UC3842 chip. The UC3842 drives the high voltage MOSFET (IRF840) directly as it has a built-in MOSFET driver. 50k resistor is used for startup from the high voltage DC bus - the UC3842 has built-in zener diode that limits voltage, provided current is low enough.
EE25 core was used for the transformer. I wound the transformer myself.
The output of the transformer is rectified with ultrafast rectifier 31DF6 and capacitor is used to filter to pure DC. The output voltage is kept regulated using a zener-optocoupler based voltage feedback loop.
NTC has been used at the input side to limit inrush current due to charging of the capacitor at the primary side. A fuse has been used for protection in case of short-circuit.
This is one of the oldest SMPS circuits I had made. I made it sometime in 2008.
_________________________________________________________________________________________________________________________
Input: 160 to 240V AC 50/60Hz
Output: 14.5v 2A (max)
The power supply is based on the dedicated offline-switcher "TOPSwitch-GX" TOP245Y, which contains both the primary PWM controller and the high-voltage MOSFET.
EE25 core was used for the transformer. I wound the transformer myself.
The output of the transformer is rectified with ultrafast rectifier MUR420 and LC filter is used to filter to pure DC. The output voltage is kept regulated using a TL431-optocoupler based voltage feedback loop.
NTC has been used at the input side to limit inrush current due to charging of the capacitor at the primary side. A fuse has been used for protection in case of short-circuit.
This is one of the oldest SMPS circuits I had made. I made it sometime in 2008.
_________________________________________________________________________________________________________________________
12VDC to 280VDC DC-DC converter for CFL inverter
Input: 11VDC to 14VDC
Output: 280VDC 60W
Was designed to drive four 15W CFL's from 12V battery.
The primary side PWM is controlled by SG3525 PWM chip. Frequency of operation is around 70kHz. The SG3525 drives the 2 MOSFETs (IRF3205) configured for push-pull topology. EI33 core is used for the transformer. It was wound by hand at home by me. The 2 MOSFETs are mounted on heatsinks.
The output of the transformer is rectified to DC with 4 ultrafast diodes (UF4007) configured as a bridge rectifier. LC filter is used to convert output to pure DC.
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Input: 160 to 240V AC 50/60Hz
Output: 12V 3A (max)
The power supply is based on the dedicated offline-switcher "TOPSwitch-GX" TOP245Y, which contains both the primary PWM controller and the high-voltage MOSFET. ETD34 core was used for the transformer. I wound the transformer myself.
_________________________________________________________________________________________________________________________
The primary side PWM is controlled by SG3525 PWM chip. It drives 2 MOSFETs (IRF3205) in push-pull configuration. The MOSFETs drive the transformer. ETD34 core was used for the transformer. The output of the transformer is converted to DC. The high-voltage DC is kept regulated by the SG3525 using direct resistive voltage-divider based feedback. This high-voltage DC is then converted to 50Hz AC using 4 MOSFETs (IRF840) in full-bridge configuration. The quasi-sine signal is generated by the 16F676. The output signals are fed into 2 IR2113 high-low side drivers that drive the MOSFET full-bridge. The 16F676 also monitors the battery voltage for low-voltage cut-out. It also monitors the load current for overload protection.
I made this circuit sometime in 2016 after lots of failure in design and implementation.
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