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ADCMP582 Comparator: Disable Latch Feature.

Question asked by DavidLee on Dec 15, 2014
Latest reply on Jul 11, 2017 by rgaddi

In the Rev A data sheet for the ADCMP582, there is a figure that illustrates a method for disabling the latch feature.

Here's the figure:

ADCMP582.JPG

I plan to use this device with Vcco=+3.3V.

The LE pin is shown connected to Vcco via a 750 Ohm resistor. Since the LE pin is terminated to VTT by 50 Ohms,

I calculate the voltage at the LE pin will be +1.4V.

The complimentary LE input, I'll call it LEBAR is connected to VTT, giving LEBAR=+1.3V.

So we see that LE is HIGH and LEBAR is LOW. This should disable the latch feature. Good.

 

My question is this: Is Figure 23 incorrect?

I ask this because the minimum Latch Enable Input Differential Voltage given in Table 1 for the ADCMP582 in PECL mode

is 200mV. The circuit of Figure 23 produces a differential of 100mV.

 

There is no discussion of Figure 23 in the data sheet.

 

Cheers,

David

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