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CD14538B: Function Table and Updated Device

CHEN YAN
Intellectual 1430 points
Part Number: CD14538B
Other Parts Discussed in Thread: SN74LVC1G123

Hi, expert,

Do you have CD14538 function table? and what's the updated device with the same function as this device? Thanks.

Best Regards

Chen

  • 0
    TI__Guru* 96947 points

    Hi Chen,

    There isn't a function table for this device, but it's operation is relatively simple. The CD14538B contains two independent retriggerable monostable multivibrators.

    When triggered, the device will output a pulse of a fixed width (determined by the timing components Rx and Cx). Because the device is 'retriggerable,' the device can be triggered again while the output pulse is occurring, and it will cause the output to extend.

    The device can be triggered with a rising edge via the +TR input or a falling edge with the -TR input. There is also a clear input that allows for interrupting the output pulse to reset the device.

    The device also includes an inverted output, which is just the opposite of the primary (Q) output.

    There are other monostable multivibrators in our portfolio (see Monostable Multivibrators), however this device doesn't have a newer version.

  • 0 in reply to Emrys Maier
    TI__Intellectual 1430 points

    Hi, Emrys

    Thanks for your reply, It's clear that the basic work principle of this device. May I understand that CD14528B has the same function table with SN74LVC1G123?

    Best Regards

    Chen

  • 0 in reply to CHEN YAN
    TI__Guru* 96947 points

    Hey Chen,

    No, they aren't the same, although they both are retriggerable monostable multivibrators.

    The CLR\ pin of the CD14528B is only indicated for resetting the device and doesn't trigger the output on release like the SN74LVC1G123. Also, the CD14528B has an inverted output while the SN74LVC1G123 does not.

    It might be helpful if you told me what you were trying to do -- do you need a monostable multivibrator with a particular function set?

  • 0 in reply to Emrys Maier
    TI__Intellectual 1430 points

    Hi, Emrys

    Thanks for your reply, my customer's sch is as following, could you please help review it？

    Actually they found that when pin5 connected to GND, pin 7 has no output, unless connect pin 5 to VCC.

    Best Regards.

    Chen

  • 0 in reply to CHEN YAN
    TI__Guru* 96947 points

    Hey Chen,

    Yes, the negative edge trigger (-TR) should be tied to BDD when unused. This is explicitly stated in the datasheet: