For the inductor current can I measure voltage across the inductor
For MOSFT I suppose it is difficult to measure drain-source voltage as R_DS(on) is very low and I cannot put a series resistor there.
Here is the design...How I´d do it: Resistor
I can´t see why you can´t use it. Tell us more about it.
IPeak current range = 10 A
Peak current range = 10 A
Expected resolution = 5 A/division
Frequency range = 100 kHz
Voltage drop < 1 V (of course, more voltage drop will create voltage imbalance and current spikes, see the schematic)
Power dissipation < 0.5 W
What other solution or information do you expect?I restate the problem...
how can I display and measure waveform of a current through an inductor and current through MOSFET switch using a digital storage oscilloscope?
I have Tektronix TDS 1002
I restate the problem...
Frequency range = 100 kHz
how can I display and measure waveform of a current through an inductor and current through MOSFET switch using a digital storage oscilloscope?
Klaus had given you this very simple and low-cost solution in the first response to your question but you rejected it outrightly. Why?Hi,
How I´d do it: Resistor
I can´t see why you can´t use it. Tell us more about it.
Klaus
Klaus had given you this very simple and low-cost solution in the first response to your question but you rejected it outrightly. Why?
I think it's simple to go with the low-ohmic value resistor in series with the inductor. Measure the voltage across it. If necessary, amplify the voltage with an Opamp. If necessay, filter out noise. Apply maths function and you're done. What's wrong with this solution? Performance deterioration? How much of it? Resistor - Current spike? How?
Please try out this cost-saving solution before you reject it.
Your rise time may be >10MHz if BW=0.35/Trise
For current sensing use a low side current shunt SMD R that drops 50mV max at max current. or less than the Ron, then amplify with DSO x1 coax or amplifier. For > 10MHz it is best to terminate in 50 Ohms at DSO for 1:1 coax.
Use calibrated 10:1probe with spring probes (no clip and gnd lead) for improved response near +20MHz due to probe ground SRF from long ground leads.
For high side current sensing use two 10:1 probes calibrated for a flat line on noise in A-B mode. again using coil spring for tip and ring on probes. ( for <=5mm gnd lead)
For clean ripple voltage use AC coupled 50 ohm terminated signals.
The key to DIff Mode sensing on DSO ( A+B invert) is short gnd leads and calibrated probes both on a large test 5V signal to get <5mV error or 60dB CMRR if possible.
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