ADCMP580 Latch Enable/Disable

Hey Guys

I'm trying to make sense of the ADCMP580 data sheet regarding the latch function. In the pin description on Page 7, Table 4, it says that the LEB pin needs to be low and LE = high in order to use the ADCMP280 in comparator mode. But on Page 12 "USING/DISABLING THE LATCH FEATURE" it says that for disabling the latch feature, the LEB and LE pins need to be the other way around (which would make sense to me since the pins are labeled as "Latch Enable"). But which one is true? And whats the function of the VTT pin exactly? An equivalent input schematic of this LEB/LE/VTT thing would be very helpful.

Thanks and regards
Fabian

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  • +1
    •  Analog Employees 
    on Jun 6, 2019 4:04 AM over 1 year ago

    HI Fabian,

    The datasheet description is consistent from table 5 and Using/Disabling the latch feature section (page 12).

    On table 5, it states that in order to disable the latch feature the following configuration must be used:

    LEB = Low
    LE   = High

    On “Using/Disabling the latch feature” section, the configuration to disable the latch mode must be (For ADCMP580):

    LEB = VEE (-5V)  
    LE   = GND

    and for ADCMP581

    LEB = VEE (-5V)
    LE   = -2V

    All these configurations provides lower voltage potential at LEB compared to LE for disabling the latch feature.
    VTT is the termination return pin for LE/LEB input pins, the Typical Application Circuit on ADCMP580 datasheet provides the typical application circuit for disabling the latch feature for the part.

    Hope this answers your question.
    Thanks Fabian.

    Best Regards,
    Dann

Reply
  • +1
    •  Analog Employees 
    on Jun 6, 2019 4:04 AM over 1 year ago

    HI Fabian,

    The datasheet description is consistent from table 5 and Using/Disabling the latch feature section (page 12).

    On table 5, it states that in order to disable the latch feature the following configuration must be used:

    LEB = Low
    LE   = High

    On “Using/Disabling the latch feature” section, the configuration to disable the latch mode must be (For ADCMP580):

    LEB = VEE (-5V)  
    LE   = GND

    and for ADCMP581

    LEB = VEE (-5V)
    LE   = -2V

    All these configurations provides lower voltage potential at LEB compared to LE for disabling the latch feature.
    VTT is the termination return pin for LE/LEB input pins, the Typical Application Circuit on ADCMP580 datasheet provides the typical application circuit for disabling the latch feature for the part.

    Hope this answers your question.
    Thanks Fabian.

    Best Regards,
    Dann

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