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Level converter for HF

Hi ng,

i'm currently building a serial controller between a 5V and a 3.3V microcontroller. Maybe someone of you can tell me, if there exists any common electronic component which can convert digital signals at ~ 1MHz with high level varying from 3.0 to 5.0 Volt and should output a signal with high level at 3.3Volt . (low level is always 0V)

first i tried to build a simple voltage divider with two resistors, which was only acceptable with stable 0V Low /5V High input... the other problem is a fixed input capacitor at the 3.3V device of 50pF which - in combination with my voltage divider - passed only low frequencies.

thanks in advance, Stefan

Reply to
Stefan Oedenkoven
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i believe you are looking for a circuit called a clamper that is then followed by a clipper.

if i understand the question correctly you have a square wave (or pulses) that are 2 V peak to peak that is floating 3 volts above ground and you wish to turn it into 3.3 volt pulses referenced to ground.

there are probably several way to accomplish this. one way would to be use an op-amp. use a capacitor to block the DC component and set the amp gain so that the output saturates (goes all the way up to the supply voltage) this helps square up the waveform. then a resister on the output and a 3.3 volt zener diode to ground. the zener will limit (clip) the waveform.

Reply to
TimPerry

not exactly... the output is from a fpga, which has a fixed high level once it is programmed. But if i reprogramm it, the high level on the same port may be higher or lower (from 3 volts to 5 volts). The low level is alway 0 volts.

FPGA => Microprocessor

0v 5v 0v 5v => 0v 3.3v 0v 3.3v reprogramm: 0v 3v 0v 3v => 0v 3.3v 0v 3.3v reprogramm: 0v 4v 0v 4v => 0v 3.3v 0v 3.3v
Reply to
Stefan Oedenkoven

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