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Small vs. larger SMT ceramic capacitors and internal inductance? – We are doing a 65A, 1V5 SMPS using a cascade of Vicor Power PRM48JH480T250A00 module and VTM48ET020T080A00 module. Vin=48V. Can you confirm that the lowest inductance ceramic capacitance is achieved by using the lower capacitance values and the larger case sizes? Read more
Isolated DC/DC input and output – I was asked to design the converter for an auto application. It still has rough requirements on the whole size and EMC performance. It seems hard to decide the main topology at first. Its input range is wide, and output power is not low. I do not know for sure the flyback is the best. Would you please share any guidance? Read more
Single-stage PFC boost converter – I need a power supply for a LED projector (19V/5A), and I thought of using a 230V/12V AC toroidal transformer (for isolation and low voltage supply) followed by a bridge rectifier and a classic PFC (boost) converter. Could I get a good enough output stability (and voltage ripple) using this single boost stage? Read more
Battery desulfation – I need to recover two of my lead-acid batteries (from a large battery bank). They seem to be affected by sulfation (some spongy white deposits on top of the plates). Does anyone have any experience with that? The batteries are just 1.5 years old, and I don’t want to lose them (though I can’t explain what happened). Read more
Need help with 25W flyback DC/DC design – I need to design a DC/DC isolated voltage regulator.
Vin 60-160 v
Vout 5V
Io=0A – 5A
Efficiency more than 83 %
The design should fit in 110x58x26 mm volume (aluminum box). I’ve included my calculations. I would like someone to check this calculation and give me advice how to minimize ripple current and increase efficiency of this flyback. Read more
SMPS problem – I need your help in one SMPS problem. It is a rectifier module supply 48V/50A for telecom equipment. When I powered on the SMPS there is a 48V for seconds then output decreases gradually till reach zero. I isolate the switching transformer and run the voltage test method all the primary volts are OK. When I connect the transformer, the problem happens again. Read more
DC-DC converter efficiency – I’m trying to write down some requirement for power supplies between 1 to 2 kW range. I do not know how much is the reasonable efficiency numbers that people achieve these days for PFC, LLC resonant and phase shifted full bridge DC-DC converters between 1 to 2 kW range at full load? Read more
Scoping output ripple voltage – We are scoping the output voltage of a 100W (1V5, 65A output), 3MHz Vicor VTM48 power module with a Scope Probe PCB Adapter (as in attached JPEG) soldered into the PCB. This is essential since the 3MHz VTM48 module cannot be scoped with the scope probe with its ground ‘tail’ clip, -because there’s too much noise like that. However, even when using this PCB probe adapter, the result is inaccurate, and there is more ripple shown on the scope than actually exists. Read more
Troubleshooting LTC3780 4 4-switch buck-boost controller – I referenced this design from LTC3780 datasheet and made some adjustment to output a 12V/max current 4A from an input range of 5-15V. I built the circuit on a breadboard and tested with an input voltage of 5V, but I am getting only 3.8-4V on the output. Can anyone enlighten me what’s wrong with my circuit design? Read more
Looking for bobbin pin current rating -I have never seen any spec for the current rating of bobbin PC pins. Various bobbins have various pin sizes and are made of different materials, copper, and brass being popular. Bobbin manufacturers are silent on the subject. Does anyone have this secret information? Read more
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