• TI Thinks Resolved

NE555: CMOS or TTL?

Part Number: NE555

At present, when using ne555 to drive MOS behind the small power LED, using switching power supply, ne555 works normally, put on the battery (lithium battery / carbonic acid) battery voltage test 13.5v. This time has been powered and the battery voltage will be down to 1v, off Turn on the battery voltage measurement, or 13,5v, disconnect the battery on the foot, the battery voltage is normal, please help confirm what is the reason Is ne555 CMOS or ttl? When reading 5v input, it is written as ttl level. Please help confirm whether the wide voltage input is cmos. Is the internal integrated transistor just ttl level? Both power modes are normal using tlc555

  • Hi User,

    This is an English forum, I translated your question and I think have a basic understanding of it. Please reply in English if you'd like continued support.

    The NE555 is bipolar, not CMOS. Can you clarify what issue you are seeing?

    -Paul
  • In reply to Paul Goedeke:

    Can NE555 TTL level support wide voltage input? Normal TTL level supports 5V.

    The main problem is that when the battery is powered, the battery voltage will be lowered. Please confirm it.

    The following is the schematic diagram. Please check it.

  • In reply to user4173409:

    Hi user,

    The trigger and threshold inputs are comparator inputs with the the other comparator inputs based on the voltage at the COMP pin. See section 8.2 of data sheet. The minimum recommended Vcc for NE555 is 4.5V. Below that voltage, it may not work correctly.

    Regards,
    Ronald Michallick
    Linear Applications

    TI assumes no liability for applications assistance or customer product design. Customer is fully responsible for all design decisions and engineering with regard to its products, including decisions relating to application of TI products. By providing technical information, TI does not intend to offer or provide engineering services or advice concerning Customer's design. If Customer desires engineering services, the Customer should rely on its retained employees and consultants and/or procure engineering services from a licensed professional engineer (LPE).

     

  • In reply to Ron Michallick:

    When the battery voltage is 13.5 V, NE555 will produce a large surge current-30A, resulting in battery protection, so there is no output, Why is this happening?
    The battery voltage measured separately is 13.5 v.
    Replacement of TLC 555. All clear.

  • In reply to user4173409:

    I see the current pulse but the current is not one of the NE555 pin signals.
    What happens at the NE555 pins?

    NE555 follows these rules.
    1 If reset is low then output is low and ignore all other rules.
    2 If trigger is low (<1/2 CONTROL) then output is high and ignore rules 3 & 4
    3 If threshold is high (>CONTROL) then output is low and ignore rule 4
    4 Output does not change.

    Regards,
    Ronald Michallick
    Linear Applications

    TI assumes no liability for applications assistance or customer product design. Customer is fully responsible for all design decisions and engineering with regard to its products, including decisions relating to application of TI products. By providing technical information, TI does not intend to offer or provide engineering services or advice concerning Customer's design. If Customer desires engineering services, the Customer should rely on its retained employees and consultants and/or procure engineering services from a licensed professional engineer (LPE).

     

  • In reply to Ron Michallick:

    When we replace TLC555, there is no current pulse.

    After power on, the current pulse is too large, resulting in battery protection, no voltage output

  • In reply to user4173409:

    Are you using the RESET function to delay output until power is stable? If not, then power up might be different for NE555 and TLC555.
    It seems that TLC555 has a power up profile that works better in your system.

    Regards,
    Ronald Michallick
    Linear Applications

    TI assumes no liability for applications assistance or customer product design. Customer is fully responsible for all design decisions and engineering with regard to its products, including decisions relating to application of TI products. By providing technical information, TI does not intend to offer or provide engineering services or advice concerning Customer's design. If Customer desires engineering services, the Customer should rely on its retained employees and consultants and/or procure engineering services from a licensed professional engineer (LPE).

     

  • In reply to Ron Michallick:

    Thank you for your answer. The problem has been solved.

    However, it was found that the first PWM waveform of the NE555 is very wide and the width of the waveform behind it is not the same. Is it related to the capacitance added to the 5th pin?
    Is the CMOS and TTL foot 5 matched capacitors different? We're using a 10NF capacitor.

  • In reply to user4173409:

    The SA555 used five prototype tests and found that the frequencies were inconsistent. The ratio of off to space was different. Each chip performed different frequencies, leading to a consistent ratio of air to space.