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 2010 after lots of failure in design and implementation.