Path: ...!3.eu.feeder.erje.net!feeder.erje.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: Cursitor Doom <cd@notformail.com>
Newsgroups: sci.electronics.repair
Subject: Re: Mitigating Signal Reflection
Date: Mon, 18 Mar 2024 14:07:46 +0000
Organization: A noiseless patient Spider
Lines: 27
Message-ID: <8higvi5snol04iej2dbu0esiomlqsr68se@4ax.com>
References: <yFLJN.29182$_a1e.6791@fx16.iad>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Injection-Info: dont-email.me; posting-host="4185ead0a5de362899bded0dccc62e22";
	logging-data="231726"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX1/HLCiREezROdyE2+ops3/eT+peJFM0FXI="
User-Agent: ForteAgent/8.00.32.1272
Cancel-Lock: sha1:ao5cFBRhvE7PGkT5xviu1ophuoE=
Bytes: 2295

On Mon, 18 Mar 2024 00:12:14 GMT, Dan <dan@nospam.invalid> wrote:

>I'm new to electronics and I'm hitting an issue beyond my skill set. I
>should start by saying I'm not 100% sure signal reflection is the issue,
>but it's my best guess.
>
>I have a 3.3V clock signal that I'm trying to convert to 5V. The clock
>speeds are sub 100 kHz. I'm using a TI level shifter, TXS0108E. Looking
>at the signal on a scope, it's a clean signal on the input and output
>side when I don't have anything connected on the output side.
>
>When I hook up the clock signal on the output side, over an
>approximately 1 meter wire the signal on the scope is full of noise. The
>scope also says the frequency is much higher than one the input signal
>should generate. I see the noise push through to the input side. I'm
>assuming this is because the level-shifter is bi-directional.
>
>I've tried a few failed solutions, like using a diode to try and block
>out the reflections, but so far no luck.
>
>Any advice on how to deal with this?

There's a possibility the fault could arise through improper use of
the level shifter, making it tip into self-oscillation when a load is
connected. This is not uncommon with voltage regulators as well. I
would suggest you strictly follow the recommendations on the data
sheet in regards to any ancillary components this device may require.