Dear Team,

May I know why series termination is not able to drive multiple loads?

Is it due to increased rise time and less current drive strength?

Regards
Hai

 

hi Hai,
To give a meaningful answer we need more details, ie: load, load type, frequency etc....................

E

 

It depends upon how many transmission lines are being driven. If it is only 1 transmission line with terminations at taps you would find reflections from each tap.

 

Series termination

https://practicalee.com/termination/

what the series resistance does is match the line impedance to the driver impedance,
so the signal is launched, and is only at half volts till it hits the end, where its now reflected to make full voltage.
The effect is to slow the edge,

Now if you drive say two loads, off one resistor, then one is going to not be at the end,
so its going to initially see half volts,

In reality, if two loads are "close" then its generally Ok, but what means close depends upon the edge speed you want.
another option, is to use two series resistors in parallel, each sending to its own line / load.

But generally, keep one load on each output

 

So it depends upon the length of the lines and the maximum frequency (or minimum transition edge speed) of the signal.

 

Series termination

https://practicalee.com/termination/

what the series resistance does is match the line impedance to the driver impedance,
so the signal is launched, and is only at half volts till it hits the end, where its now reflected to make full voltage.
The effect is to slow the edge,

Now if you drive say two loads, off one resistor, then one is going to not be at the end,
so its going to initially see half volts,

In reality, if two loads are "close" then its generally Ok, but what means close depends upon the edge speed you want.
another option, is to use two series resistors in parallel, each sending to its own line / load.

But generally, keep one load on each output

Hi Andrew,

Thank you.

Regards
HARI