Datasheet MAX961-MAX964, MAX997, MAX999 (Maxim) - 8
| Manufacturer | Maxim |
| Description | Single/Dual/Quad, Ultra-High-Speed, +3V/+5V, Beyond-the-Rails Comparators |
| Pages / Page | 13 / 8 — Detailed Description. Timing. Input Stage Circuitry |
| File Format / Size | PDF / 1.8 Mb |
| Document Language | English |
Detailed Description. Timing. Input Stage Circuitry
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MAX961–MAX964/ Single/Dual/Quad, Ultra-High-Speed, +3V/+5V, MAX997/MAX999 Beyond-the-Rails Comparators
Detailed Description
teresis effectively causes one comparator input voltage to The MAX961–MAX964/MAX997/MAX999 single-supply move quickly past the other, thus taking the input out of comparators feature internal hysteresis, ultra-high-speed the region where oscillation occurs. Standard compara- operation, and low power consumption. Their outputs are tors require hysteresis to be added with external resistors. guaranteed to pull within 0.52V of either rail without exter- The fixed internal hysteresis eliminates these resistors. nal pullup or pulldown circuitry. Beyond-the-Rails input The MAX961/MAX963 include internal latches that allow voltage range and low-voltage, single-supply operation storage of comparison results. LE has a high input make these devices ideal for portable equipment. These impedance. If LE is low, the latch is transparent (i.e., the comparators all interface directly to CMOS logic. comparator operates as though the latch is not present).
Timing
The comparator’s output state is stored when LE is pulled high. All timing constraints must be met when using the Most high-speed comparators oscillate in the linear region latch function (Figure 2). because of noise or undesirable parasitic feedback. This can occur when the voltage on one input is close to or
Input Stage Circuitry
equal to the voltage on the other input. These devices The MAX961–MAX964/MAX997/MAX999 include internal have a small amount of internal hysteresis to counter protection circuitry that prevents damage to the preci- parasitic effects and noise. sion input stage from large differential input voltages. The added hysteresis of the MAX961–MAX964/MAX997/ This protection circuitry consists of two groups of three MAX999 creates two trip points: one for the rising input front-to-back diodes between IN+ and IN-, as well as two voltage and one for the falling input voltage (Figure 1). 200Ω resistors (Figure 3). The diodes limit the differential The difference between the trip points is the hysteresis. voltage applied to the comparator’s internal circuitry to no When the comparator’s input voltages are equal, the hys- more than 3VF, where VF is the diode’s forward-voltage drop (about 0.7V at +25°C). VTRIP+ VIN+ VHYST VTRIP+ + VTRIP- VOS = 2 VIN- = 0V VTRIP- VOH Q VOL Q VOH VOL Figure 1. Input and Output Waveforms, Noninverting Input Varied www.maximintegrated.com Maxim Integrated │ 8
Detailed Description
teresis effectively causes one comparator input voltage to The MAX961–MAX964/MAX997/MAX999 single-supply move quickly past the other, thus taking the input out of comparators feature internal hysteresis, ultra-high-speed the region where oscillation occurs. Standard compara- operation, and low power consumption. Their outputs are tors require hysteresis to be added with external resistors. guaranteed to pull within 0.52V of either rail without exter- The fixed internal hysteresis eliminates these resistors. nal pullup or pulldown circuitry. Beyond-the-Rails input The MAX961/MAX963 include internal latches that allow voltage range and low-voltage, single-supply operation storage of comparison results. LE has a high input make these devices ideal for portable equipment. These impedance. If LE is low, the latch is transparent (i.e., the comparators all interface directly to CMOS logic. comparator operates as though the latch is not present).
Timing
The comparator’s output state is stored when LE is pulled high. All timing constraints must be met when using the Most high-speed comparators oscillate in the linear region latch function (Figure 2). because of noise or undesirable parasitic feedback. This can occur when the voltage on one input is close to or
Input Stage Circuitry
equal to the voltage on the other input. These devices The MAX961–MAX964/MAX997/MAX999 include internal have a small amount of internal hysteresis to counter protection circuitry that prevents damage to the preci- parasitic effects and noise. sion input stage from large differential input voltages. The added hysteresis of the MAX961–MAX964/MAX997/ This protection circuitry consists of two groups of three MAX999 creates two trip points: one for the rising input front-to-back diodes between IN+ and IN-, as well as two voltage and one for the falling input voltage (Figure 1). 200Ω resistors (Figure 3). The diodes limit the differential The difference between the trip points is the hysteresis. voltage applied to the comparator’s internal circuitry to no When the comparator’s input voltages are equal, the hys- more than 3VF, where VF is the diode’s forward-voltage drop (about 0.7V at +25°C). VTRIP+ VIN+ VHYST VTRIP+ + VTRIP- VOS = 2 VIN- = 0V VTRIP- VOH Q VOL Q VOH VOL Figure 1. Input and Output Waveforms, Noninverting Input Varied www.maximintegrated.com Maxim Integrated │ 8
