Product Summary

This article introduces a digital isolator (Si87xx) that can be used with photocouplers and pin compatibility.

By incorporating an LED emulator circuit on the input (primary) side, the input side consists of only the anode and cathode terminals like a photocoupler, eliminating the need for the VDDI power supply on the input side required for a digital isolator. . Improvements are expected in the temperature characteristics, characteristic fluctuations due to aging deterioration, and characteristics such as CMTI, which are problems of photocouplers. Propagation delay time is minimized, especially at high temperatures, and characteristics against voltage and temperature are stable. We also have a lineup (model number list) that is pin-compatible with photocouplers and can be replaced.

Please refer to "Replacement materials with photocouplers" on the latter half of this page.
Please refer to this link for structural differences and technical comparisons for photocouplers.
See here for articles on how to improve the characteristics of digital isolators such as photocouplers and Si87xx.

Comparison of delay characteristics

Compared to photocouplers, digital isolators are less affected by temperature changes and deterioration over time, and have less delay time, making them ideal for isolating high-speed signal lines. The photocoupler adjusts the characteristics of the CRT so that they are maximized at room temperature, and the characteristics fluctuate with temperature fluctuations.

Digital isolators, on the other hand, have little change in their characteristics due to temperature and guarantee their characteristics over a wide temperature range of -40 to +125°C.

UVLO

The Si8715~20 and Si8735/36 have a built-in UVLO (Under Voltage Lock Out) circuit.

When the supply voltage falls below the UVLO threshold voltage, the output unconditionally defaults to prevent operation. In order to output a stable signal, it is output after a certain time tSTART after the power supply terminal has fully risen. Hysteresis is provided for the voltage applied to UVLO and the voltage released.

(The figure is an image)

Product lineup

Si8715~20

The insulation voltage is certified to 5KVrms by UL1577. It has a surge resistance of 10KV and a withstand voltage of 5V, making it ideal for isolating signals up to 15Mbps.
The input current threshold is 3.6mA (max) and CMTI is as high as 35kV/us (@IF=6mA) min.

Inverted output/non-inverted output EN terminal products are also available.

Si8715, Si8719
SOIC-8 and DIP8/GW package products

Si8716, Si8717, Si8718, Si8720
Products with EN terminal

.

Si8715, Si8719
SDIP6 package

Si8735/36

The insulation voltage is 2.5KVrms according to UL1577. 10KV surge withstand, ideal for isolating 15Mbps signals.
The input current threshold is as low as 0.68mA (typ).

Si8735: Non-inverted output Si8736: Inverted output + EN pin

Si8735
Non-inverted output type

Si8736
Inverted output + EN terminal

Si8710-12

Open collector output isolator. The output withstand voltage is 36V, and it can also be used as a gate driver.
No UVLO.

Si8710
Product of Open C Output

Si8711
​ ​Built-in 20KΩ pull-up resistor

Si8712 with EN terminal

Si8710 SDIP6 package

As a gate driver for the LED emulator input, there is the Si826x series with an output peak current of up to 4A.

Product list

Please be sure to check the data sheet for details.

[Download material] Replacement material with photocoupler

We have prepared a model number list as a guideline for selecting alternatives from existing photocouplers.
If you are interested, please apply from [Download materials here] below.

　
*These information are estimated by Skyworks based on each manufacturer's information at the time of acquisition. Please judge the applicability after evaluation by the customer.
*Information subject to change without notice. the Company do not make any guarantees regarding the accuracy of the information.

Target application

There are products that can be used pin-compatible with photocouplers that have a power supply terminal on the output side. When changing the design from a photocoupler to a highly reliable digital isolator, almost the same circuit can be replaced.

Digital isolators can provide stable propagation delay characteristics even in environments from room temperature to high temperature, are standardized including temperature fluctuations, and have little deterioration over time, making it easy to design and eliminating the need to set the current in consideration of deterioration over time.It is the ideal solution for industrial systems that are expected to be used in harsh environments such as high temperature environments and long-term continuous operation.

• Industrial equipment, control equipment
• motor control
• Power isolation switch
• Isolation of digital signals such as ADC
• Equipment such as testers
• EV traction inverter, etc.

Evaluation Board

This is a sample pack for alternative evaluation with a photocoupler.
Si87xx Optocoupler Replacement Isolators Sample Pack

Evaluation board for performance evaluation of the Si871x LED emulator input isolator. Equipped with 8 DIPs, detailed specification evaluation and connection evaluation to existing boards are possible.
si871xdip8-kit

There are similar evaluation boards in different packages below.
si871xsdip6-kit　
si871xsoic8-kit　

si87xxsdip6-kit　
si87xx dip8-kit　
si87xxsoic8-kit　


For details, please refer to related documents UG515, UG507 and UG508.

Related articles/materials

• Digital isolator and photocoupler technology
• Main characteristics/functional differences due to differences in the structure of various isolators
• Digital isolator parameters and definitions
• Characteristics upgrade by replacing photocouplers
• Digital isolator and photocoupler technology Structure and basic technology
• Isolated gate driver "Si826x" compatible with photocouplers

Inquiry / Quotation

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