u/electrogasmYT

Hey everyone,

​I'm working on a 20V to 12V buck converter for battery charging purposes, aiming for around 10A current.

​The Setup:

I'm using an IR2104 gate driver to drive a single N-channel MOSFET for high-side switching. Since I’m implementing an asymmetric buck topology with an output inductor and a Schottky freewheeling diode, I’m considering not using the 'LO' pin and driving the high-side MOSFET directly with the PWM signal.

​My concerns:

​Will the freewheeling diode (Schottky) be enough to pull the VS pin low during the off-time to charge the bootstrap capacitor?

​What are the risks of using the IR2104 in this configuration for long-term battery charging?

​Any suggestions for handling the gate drive signal to avoid spikes and potential MOSFET failure?

​I’m using a high-current Schottky diode for the freewheeling path and planning to implement a software-based CC-CV loop via an MCU.

​Looking for some raw feedback and technical advice before I fry my components. Has anyone tried this "LO-less" configuration before?

I'm designing a small oscilloscope using an RP2040 Pico (3.3V ADC) and need a safe analog front-end.

Requirements:

• Input voltage: up to ±30V (accidental reverse polarity is possible)
• Frequency range: 20 Hz to 50 kHz
• Preserve waveform shape and amplitude as much as possible
• Protect the RP2040 ADC from negative voltage and overvoltage
• Low-cost design (no expensive analog front-end ICs)

I've seen many different approaches:

• High-value resistor divider
• Series resistor + Schottky clamp diodes
• AC coupling with 1.65V bias
• TVS diodes
• Op-amp buffer
• Various combinations of the above

I'm looking for a front-end that provides good protection without noticeably distorting the waveform in the 20 Hz–50 kHz range.

If you've designed a similar oscilloscope or analog front-end for an RP2040 (or any MCU ADC), what circuit would you recommend? A schematic or practical design example would be greatly appreciated.

I'm designing a small oscilloscope using an RP2040 Pico (3.3V ADC) and need a safe analog front-end.

Requirements:

• Input voltage: up to ±30V (accidental reverse polarity is possible)
• Frequency range: 20 Hz to 50 kHz
• Preserve waveform shape and amplitude as much as possible
• Protect the RP2040 ADC from negative voltage and overvoltage
• Low-cost design (no expensive analog front-end ICs)

I've seen many different approaches:

• High-value resistor divider
• Series resistor + Schottky clamp diodes
• AC coupling with 1.65V bias
• TVS diodes
• Op-amp buffer
• Various combinations of the above

I'm looking for a front-end that provides good protection without noticeably distorting the waveform in the 20 Hz–50 kHz range.

If you've designed a similar oscilloscope or analog front-end for an RP2040 (or any MCU ADC), what circuit would you recommend? A schematic or practical design example would be greatly appreciated.

https://preview.redd.it/ogt98ev6qu6h1.png?width=2923&format=png&auto=webp&s=3313e8f15e1b51a112e4fdbef8c0ed715a72aa89

I'm working on a conceptual buck converter and would appreciate a sanity check on the gate-drive method.

• Input: 25V
• IRF4905 as the high-side switch
• TLP250 driven by an Arduino Nano (~25 kHz PWM)
• TLP250 VCC connected to +25V
• TLP250 GND connected to the 7812 output
• 7812 input connected to +25V and its GND pin to system ground

The idea is to use the TLP250 to pull the P-MOSFET gate low relative to its source.

Is this concept fundamentally sound, or am I missing something important? Any obvious issues with this approach?

https://preview.redd.it/gn4htwmdrg5h1.png?width=1440&format=png&auto=webp&s=bd36ebf7f0137f035dc401588d4b6e43e2967145