What is the maximum speed of the Logic Level Converter Bi-Directional (CE07510). Specifically will it support 800KHz Neopixels?
thanks
Tony
Tony
I believe this is one of the uses quoted for this sort of thing so I imagine it would. But you never know …
Actually 800kHz is pretty slow and I think the frequency response of most Mosfets (which is the governing factor) would be OK at this frequency.
Cheers Bob
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Thanks Bob
Hi Tony,
It definitely will work! I’ve got some floating around the house and they work perfectly for getting 5V logic level WS2812 strips connected to a 3.3v device, such as a Pico or Raspberry Pi.
Liam.
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The data sheet Dynamic Characteristics show capacitance at frequency of 1.0 MHz.
So should work ok at 800KHz. Wouldn’t want to push it beyond 1.0 MHz though, capacitance would be an issue.
Regards
JIm
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Thanks Liam
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Hi James
Probably the switch on/off time has the most bearing on frequency. The input capacitance would come into play when you have to use too high current limiting resistor to protect things like Arduino output points etc. This then increases the time constant considerably some Mosfet capacitance can get to 1.5nF or so. If switching large currents with the slow switching times heating becomes another issue as the Mosfet is taking too long to switch fully on. Current limiting resistors are reduced or almost eliminated by using a PNP/NPN suitable transistor pair or dedicated Mosfet drivers (which come in IC form) to charge and discharge this cap.
The frequency will have no bearing on a capacitor value. The reactance changes with frequency not the cap value. I think the 1MHz referred to in the spec is the frequency the test was done at.
Cheers Bob
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Agree.
It is about half the reliable switching speed based on the figures in the table above.
And to my limited understanding, it is what I would take as the maximum to use.
So 800KHz would be fine.
Cheers
Jim
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