LMV7219 Datasheet, PDF (10/25 Pages) National Semiconductor (TI) – 7 nsec, 2.7V to 5V Comparator with Rail-to Rail Output

LMV7219
SNOS458G – APRIL 2000 – REVISED JANUARY 2015
7 Detailed Description
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7.1 Overview
LMV7219 is a single supply comparator with internal hysteresis, 7 ns of propagation delay and only 1.1 mA of
supply current.
The LMV7219 has a typical input common mode voltage range of −0.2 V below the ground to 1 V below V_cc. The
differential input stage is a pair of PNP transistors, therefore, the input bias current flows out of the device. If
either of the input signals falls below the negative common mode limit, the parasitic PN junction formed by the
substrate and the base of the PNP will turn on, resulting in an increase of input bias current.
7.2 Functional Block Diagram
7.3 Feature Description
If one of the inputs goes above the positive common mode limit, the output will still maintain the correct logic
level as long as the other input stays within the common mode range. However, the propagation delay will
increase. When both inputs are outside the common mode voltage range, current saturation occurs in the input
stage, and the output becomes unpredictable.
7.4 Device Functional Modes
The propagation delay does not increase significantly with large differential input voltages. However, large
differential voltages greater than the supply voltage should be avoided to prevent damages to the input stage.
The LMV7219 has a push-pull output. When the output switches, there is a direct path between V_CC and ground,
causing high output sinking or sourcing current during the transition. After the transition, the output current
decreases and the supply current settles back to about 1.1 mA at 5 V, thus conserving power consumption.
Most high-speed comparators oscillate when the voltage of one of the inputs is close to or equal to the voltage
on the other input due to noise or undesirable feedback. The LMV7219 has 7 mV of internal hysteresis to counter
parasitic effects and noise. The hysteresis does not change significantly with the supply voltages and the
common mode input voltages as reflected in the specification table.
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