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Digital input receiver with hysteresis for digital input modules

HARANATH VASAM1
Intellectual 300 points
Other Parts Discussed in Thread: ISO1212, ISO1211

We are looking for Digital Input Receiver with hysteresis with following specifications

S.No

Description

Details

1

Pulse counter frequency – Pulse counter inputs.

1kHz (Maximum)

2

Input voltage level

220 V/ 24 V DC

3

Debounce time

5 ms

4

Hysteresis

Refer table and Picture below

5

Test Compliance

 

 

EMI/EMC

5kV impulse

2kV dielectric withstand

Hysteresis Values for different inputs

S.No

Input Range

VTR1

VTR2

1

220V DC

110V

 63V

2

110V DC

34.4V

 50V

3

  48V DC

13.5V

17.4V

4

  24V DC

  5V

10.1V

We have found the silicon labs part si838x, however we are interested in using TI part. Please suggest the suitable part.

Thanks in Advance
  • 0
    TI__Expert 6955 points

    HARANATH,

    The ISO1211 or the ISO1212 are what we have to offer for digital inputs. The datasheet and the calculator spreadsheet  contain the information needed to implement these devices. Please let me know if you have any more questions.

    Respectfully,

    Lucas

  • 0 in reply to Lucas Schulte9
    TI__Expert 6955 points

    HARANATH,

    Linked below is also a good TI Tech Note about how to design for high voltage digital input with the ISO121x.

    http://www.ti.com/lit/SLLA382

    Respectfully,

    Lucas

  • 0 in reply to Lucas Schulte9
    Intellectual 300 points

    Hi Lucas,

    Thanks for the quick reply. Documents, which you have shared are very useful. We have few more questions

    1) Is there in built Low-PassDebounce Filter in ISO1211?

    2) For 240V DC input, we would like to give input to ISO1211 as follows

    use potential divider and step down to 48V --> Connect to ISO1211 through RTHR,RSHUNT and RSENSE

    (these values will be as per 48V input in the given table - RTHR=8 kΩ, RSENSE=560 Ω, RSHUNT=1000 kΩ  (That is: RSHUNT not needed))

    Thanks

    HARANATH

    RTHR=8 kΩ, RSENSE=560 Ω, RSHUNT=1000 kΩ  (That is: RSHUNT not needed)
  • 0 in reply to HARANATH VASAM1
    TI__Expert 6955 points

    HARANATH,

    Sorry for the late response here.

    1) No there is not an internal filter. Generally Cin is used to filter the inputs and achieve debounce.

    2) Are you asking me to confirm these values? If so, did you use the design guide or datasheet and excel sheet calculator to calcuate these values? What is your desired input high and low logic thresholds?

    Respectfully,

    Lucas