ECL Information
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ECL:- Emitter Coupled Logic This is an extremely fast logic type, but uses a lot of power. The main features are:- Very small voltage swing, typically 0.8 volts, from -0.8 to -1.6 volts.
Picture of a ECL Waveform
ECL output waveform
Negative supply voltage with logic levels referred to the positive (ground) supply.
All outputs need pull-down resistors to work. These are usually placed near the input being driven by an output, to minimise signal reflections. A typical pull down resistor is 50 ohms to -2 volts.

Outputs can drive 50 ohms directly.

Complementary outputs are available on most gates and outputs can be connected together to give a "wired or".

Differential input line receiver gates are available.

Low voltage swing and rise and fall time that is slow compared to transition time means that crosstalk and ground bounce effects are small.

Power consumption is not affected by switching rate.

Inputs have pull down resistors of about 50 kohms so unused inputs go low.

Inputs must not be connected to the positive supply.

History:-
10k series. -5.2 volt supply. Output and input levels change with temperature and supply voltage.

10kH series. -5.2 volt supply. Output and input levels change with temperature but not with supply voltage.

100k series. -4.2 to -5.7 volt supply. Output and input levels do not change.

100300 series. Lower power version of 100k series.

Different series (or, if levels change, where there are different voltages or temperatures) are best connected like this:-

Picture of a Circuit diagram Interfacing different ECL series, with the complementary outputs driving a differential reciever.
TTL, CMOS, ECL, Back to:- Information on Logic Outputs

 
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