optocoupler vs transformer
APPLICATION NOTE 1002
ISO
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Isolink Optocouplers vs. Pulse Transformers
In isolation applications where one needs to pass signals in presence of transient or continuous high voltages, reject extreme noise, and break ground loops, optical (optocouplers) and magnetic (pulse transformers) coupling isolation are often used. However pulse transformers are much more difficult to design with relative to optocouplers. When dealing with pulse transformers, the load becomes more critical than with any other type of transformer. Leakage and primary inductance values take on added significance because of the effect they have on the output waveshape. If the load disturbs this wave shape, severe problems can be created. [1]
In many applications, it is difficult to obtain a usable waveform with a pulse transformer (See Figure 1). This is essentially due to three factors: waveforin droop, effects of the turns ratio on risetime, and backswing. [2]
A comparision between transfromer and optocoupler characteristics are presented in Table 2.
Optocouplers are being used to replace pulse transformers due to their ease of design, simplicity, and smaller size. The use of state-of-the-art AlGaAs emitters in
Isolink’s optocouplers has greatly improved performance and reliability. AlGaAs LED emitters are brighter, faster, more efficient and linear, and slower to degrade than
GaAs and GaAsP type emitters used in older optocoupler designs. For hybrid assembly applications, Isolink offers the OLI optocoupler family in a small size,.100" X.110"
X.045" high, package.
Figure 1. Output Waveform Comparisions:
Optocoupler vs. Pulse Transformer
for “chip and wire” assembly. For applications requiring hermetic packaging, optocouplers are available in
6-pin leadless chip carrier (LCC) surface mount packages or TO-5 packages. Isohnk’s products range from simple phototransistor outputs to high speed, high common mode rejection logic gates. The typical data rates
ISO
LINK
Isolink Optocouplers vs. Pulse Transformers
In isolation applications where one needs to pass signals in presence of transient or continuous high voltages, reject extreme noise, and break ground loops, optical (optocouplers) and magnetic (pulse transformers) coupling isolation are often used. However pulse transformers are much more difficult to design with relative to optocouplers. When dealing with pulse transformers, the load becomes more critical than with any other type of transformer. Leakage and primary inductance values take on added significance because of the effect they have on the output waveshape. If the load disturbs this wave shape, severe problems can be created. [1]
In many applications, it is difficult to obtain a usable waveform with a pulse transformer (See Figure 1). This is essentially due to three factors: waveforin droop, effects of the turns ratio on risetime, and backswing. [2]
A comparision between transfromer and optocoupler characteristics are presented in Table 2.
Optocouplers are being used to replace pulse transformers due to their ease of design, simplicity, and smaller size. The use of state-of-the-art AlGaAs emitters in
Isolink’s optocouplers has greatly improved performance and reliability. AlGaAs LED emitters are brighter, faster, more efficient and linear, and slower to degrade than
GaAs and GaAsP type emitters used in older optocoupler designs. For hybrid assembly applications, Isolink offers the OLI optocoupler family in a small size,.100" X.110"
X.045" high, package.
Figure 1. Output Waveform Comparisions:
Optocoupler vs. Pulse Transformer
for “chip and wire” assembly. For applications requiring hermetic packaging, optocouplers are available in
6-pin leadless chip carrier (LCC) surface mount packages or TO-5 packages. Isohnk’s products range from simple phototransistor outputs to high speed, high common mode rejection logic gates. The typical data rates