Datasheet MAX907, MAX908, MAX909 (Maxim) - 9

Dual/Quad/Single, High-Speed, Ultra-Low-Power, Single-Supply TTL Comparators Pin Description PIN NAME FUNCTION MAX907 MAX908 MAX909
1 1 — OUTA Comparator A Output 2 2 — INA- Comparator A Inverting Input 3 3 — INA+ Comparator A Noninverting Input 4 11 6 GND Ground 5 5 — INB+ Comparator B Noninverting Input 6 6 — INB- Comparator B Inverting Input 7 7 — OUTB Comparator B Output 8 4 1 V+ Positive Supply — 8 — OUTC Comparator C Output — 9 — INC- Comparator C Inverting Input — 10 — INC+ Comparator C Noninverting Input — 12 — IND+ Comparator D Noninverting Input — 13 — IND- Comparator D Inverting Input — 14 — OUTD Comparator D Output — — 2 IN+ Noninverting Input — — 3 IN- Inverting Input
MAX907/MAX908/MAX909
— — 4 V- Negative Supply or Ground The latch is transparent when LE is low. The comparator output is — — 5 LE stored when LE is high. — — 7 QOUT Comparator Output — — 8 QOUT Inverted Comparator Output
Detailed Description
Adding hysteresis to a comparator creates two trip points: one for the input voltage rising and one for the
Timing
input voltage falling (Figure 1). The difference between Noise or undesired parasitic AC feedback cause most these two input-referred trip points is the hysteresis. high-speed comparators to oscillate in the linear region Figure 1 illustrates the case where IN- is fixed and IN+ (i.e., when the voltage on one input is at or near the is varied. If the inputs were reversed, the figure would voltage on the other input). The MAX907/MAX908/ look the same, except the output would be inverted. MAX909 eliminate this problem by incorporating inter- The MAX909 includes an internal latch, allowing the nal hysteresis. When the two comparator input voltages result of a comparison to be stored. If LE is low, the are equal, hysteresis effectively causes one comparator latch is transparent (i.e., the comparator operates as input voltage to move quickly past the other, thus taking though the latch is not present). The state of the com- the input out of the region where oscillation occurs. parator output is stored when LE is high (Figure 2). Standard comparators require that hysteresis be added through the use of external resistors. The Note that the MAX909 can be operated with V- con- MAX907/MAX908/MAX909’s fixed internal hysteresis nected to ground or to a negative supply voltage. The eliminates these resistors (and the equations required MAX909’s input range extends from (V- - 0.2V) to to determine appropriate values). (V+ - 1.5V).
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Document Outline not-recomm-data-sheet-cover.pdf Not Recommended for New Designs not-recomm-data-sheet-coverMAX909.pdf Not Recommended for New Designs