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LM311-N: sink current capability

cafain
Mastermind 6805 points

Part Number: LM311-N

Hi, Staff

The LM311-N (SNOBJ1E) description states:
[Further, they can drive lamps or relays, switching voltages up to 50V at currents as high as 50 mA.]

Please provide your comments below.
1. I understand that the sink current capability of Out (pin 7) is 50 mA; is this correct?
2. Is it okay to sink 50mA for a relatively long period of time?
(Will this cause overheating and stress on the device?)
3. Are there specified minimum and maximum values ​​for the sink current at the Out terminal?

An issue has been identified where the comparator output settles at an intermediate potential when the switch is turned on.
(The pull-up resistor for the OUT terminal is connected to 20V. While the expected output is 20V when the switch is off and 0V when it is on, the actual output is approximately 13V when the switch is on.)

best regards
cafain

  • 0
    TI__Guru**** 173716 points

    Hello Cafain,

    1) Yes 50mA

    2) Yes if temperature is not excessive.

    3) There is this spec.

    If on transistor voltage is 13V and current is 50mA, then power is 650mW; that is too much.

    Can you show a schematic? How many samples work as desired and how many have 13V?

  • 0 in reply to Ron Michallick
    Mastermind 6805 points

    Hello Ron san

    Thank you for your support. I apologize for the delay in getting back to you.

    As this is a customer's circuit, I cannot disclose the details. I will give further consideration to the circuit configuration.

    The output uses a 20V pull-up with a 4.7kΩ resistor.

    I would appreciate your support should any issues arise.

    regards cafain

  • 0 in reply to cafain
    TI__Guru**** 173716 points

    Cafain,

    Is this a new or old design? How many samples fail out of how many tested? What are the supply voltages [8,4] and ground [1] voltage. 

  • 0 in reply to Ron Michallick
    Mastermind 6805 points

    Ron-san

    I will provide the following information.

    Datasheet(SNOSBJ1E) page12
    「CIRCUIT TECHNIQUES FOR AVOIDING
    　OSCILLATIONS IN COMPARATOR APPLICATIONS」
    Regarding the items listed here, I am concerned about the fact that pins 5 and 6 are in an OPEN state.

    It features a new design.
    However, since this device has long been used in a wide variety of applications, it is also being used in this application.
    An output malfunction was confirmed in one unit.

    1pin : GND(0V)
    2pin : 5V (Set the 10V reference output to 5V using a resistive divider)
    3pin : 6.2V (Target voltage for measurement : Comparator turns ON when the 6.2V drops to 5V or below)
    4pin : GND(0V)
    5pin : open
    6pin : open
    7pin : 20V-4.7kohm Pull-up)
    8pin : 20V

    regards cafain

  • 0 in reply to cafain
    TI__Guru**** 173716 points

    Cafain-san,

    cafain said:
    An output malfunction was confirmed in one unit.

    This one unit is bad, damaged.

  • 0 in reply to Ron Michallick
    Mastermind 6805 points

    Ron-san

    So, it is indeed damaged. I will consider the possibility of EOS or ESD. Thank you very much.

    regards