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Differential Line Driver Problem

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jkal

New Member
Hey

I am working on an electronics project for my lab. I have 2 different signals that get put through a few differential line drivers. One of those signals is a 10 MHz clock, but the output of this clock is 8V peak to peak for the negated side and 4V peak to peak for the other output when it should be 5V for both. The second signal has proper output amplitudes. Does anyone have an idea of what might be causing this?

I am using the am26ls31 driver.

Thanks in advanced
 

MikeMl

Well-Known Member
Most Helpful Member
Probably how the bus is terminated at the far end? You must use the recommended differential line receiver(s) and termination resistors (i.e. maintain a "balanced" line pair).
 

elfenlied102938

New Member
Hi,

I am also using the AM26LS31M for a project, and I am seeing this intermittent problem where one of the output signals is corrupt. For example, if the input signal is a single 5V pulse of 1ms (0V-5V-0V), the (+) should go 0V-5V-0V for 1ms and (-) should go 5V-0V-5V for 1ms.

What I'm seeing is that while (-) does 5V-0V-5V for 1ms, (+) does 0V-5V-2.5V-0V (like a tetris "L" block with sharp transitions), where the 5V stays on for 1ms like (-) but the mid-level 2.5V stays on for 3ms before finally dropping down to 0V. This 0V level thereafter is "dirty" (not a nice straight line) What could be the cause of this? Is this a problem with the chip or the load? I am suspecting there's something wrong with the load.

The load is a motor driver, whose input can be represented with +5V-R_pullup-Rt-R_pulldown-GND, with (+) and (-) signals between Rt and into the amplifier).

Thanks.
 

Roff

Well-Known Member
Hi,

I am also using the AM26LS31M for a project, and I am seeing this intermittent problem where one of the output signals is corrupt. For example, if the input signal is a single 5V pulse of 1ms (0V-5V-0V), the (+) should go 0V-5V-0V for 1ms and (-) should go 5V-0V-5V for 1ms.

What I'm seeing is that while (-) does 5V-0V-5V for 1ms, (+) does 0V-5V-2.5V-0V (like a tetris "L" block with sharp transitions), where the 5V stays on for 1ms like (-) but the mid-level 2.5V stays on for 3ms before finally dropping down to 0V. This 0V level thereafter is "dirty" (not a nice straight line) What could be the cause of this? Is this a problem with the chip or the load? I am suspecting there's something wrong with the load.

The load is a motor driver, whose input can be represented with +5V-R_pullup-Rt-R_pulldown-GND, with (+) and (-) signals between Rt and into the amplifier).

Thanks.
Post a schematic or datasheet of your motor driver.
 
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