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ISO1228: Source/sink support the ISO1228

Chen Alex1
Genius 4635 points

Part Number: ISO1228
Other Parts Discussed in Thread: ISO1212,

Tool/software:

HI SIR

Due to the product consistency

may i know if the iso1228 can support the Source//Sink in the same board?

we don't want to Divided into two boards

thanks

  • 0
    TI__Mastermind 34580 points

    Hi Alex, 

    Thank you for reaching out. ISO1228 can support both modes without changing the board configuration. See the Sink/Source mode EVM as an example (ISO1228EVM Evaluation board | TI.com). However, all 8 channels need to be either sink OR source (the ISO1228 cannot support 4-sink and 4-source mode channels at the same time). 

    ISO1212 has independent channels and can support sink/source modes. At the same time. 4 units of ISO1212 would be needed for 8-channels. 

    Best,
    Andrew

  • 0 in reply to Andrew J
    Genius 4635 points

    hi Andrew

    Due to old design is use the bi-directly opto coupler, so our product can accpet the source /sink signal, and don;t modify circuit

    but iso1228 need a power for primary side, we need the switch the power polarity when source or sink module, right?

    thanks

  • 0 in reply to Chen Alex1
    TI__Mastermind 34580 points

    Hello Alex, 

    The ISO1228's power pins will not change for sink or source modes (pins AVCC and AVSS). These will always stay 24V and 0V (see abs max conditions). However, the direction of the INx and LEDx connections will effectively change. 

    The ISO1228EVM (sink/source mode EVM) is designed to handle both modes without a change to the PCB. The datasheet was recently updated to include a sink/source configuration diagram (see 8.2.3 Sink/Source Type Digital Inputs for more details). 

     

    "The full bridge diode rectifier shown in box 2 is needed connect COM1 and COM2 to AVCC and AVSS in both modes of operation. ISO1228 inputs are configured to sink type when COM2 = 24V and COM1 = GND. ISO1228 is configured to source mode when COM1 = 24V and COM2 = GND. Each channel needs to have back-to-back LEDs connected on LEDx pins to have LED indicators in both modes. Two back-to-back diodes can be connected to the AVSS instead of LEDs if LED indication is not needed as shown in dotted box 1. ISO1228 in a sink/source isolated digital input configuration only needs 6 diodes shown in box 1 and box 2." -8.2.3 Sink/Source Type Digital Inputs

    Best,
    Andrew