Practical index for comparator families (low-power, precision, high-speed/latched, regenerative, RR/high-voltage, window/zero-cross, timer/one-shot), output types (open-drain/push-pull), isolation chains, nano-power starts; plus Schmitt-trigger buffers, programmable hysteresis, application recipes, key specs, and design hooks.
Comparator Families
General-Purpose Low-Power Comparator
nA–µA Iq with ms–µs delays and RR input—great for battery and slow thresholds.
Precision Low-Offset Comparator
Low offset/drift; add small external hysteresis for accurate thresholds/windows.
High-Speed / Latched Comparator
ns-level delay with low edge jitter; optional latch for sampling/timing/ToF.
Regenerative (StrongARM-Type)
Clocked dynamic front-ends with ultra-low offset—ideal for SAR/TDC inputs.
Open-Drain / Open-Collector Output
Wired-OR, cross-voltage domains with pull-ups; multi-point alarms and wired-AND logic.
Push-Pull Output Comparator
Clean edges and no pull-up required; stronger drive for PWM/squaring.
Rail-to-Rail Input Comparator
Maintains threshold accuracy near supply rails—useful at low VDD.
Wide-Input / High-Voltage Comparator
Handles tens to hundreds of volts with protection/dividers for auto/industrial fronts.
Comparator with Built-In Reference
Integrated precision Vref/DAC for power-on thresholds and programmable limits.
Window Comparator
Upper/lower window with hysteresis—great for 4–20 mA and temp/voltage compliance.
Zero-Crossing Comparator
Symmetric hysteresis, low drift and mains-noise rejection for AC zero detect/phase sync.
Isolated Comparator Chain
ΣΔ modulator + digital isolator with high CMTI for high-side/bus fault detection.
Sub-1V / Nano-Power Comparator
Ultra-low start voltage and dynamic bias for harvesting and wake-up.
Comparator with One-Shot / Timer
Generate timeout pulses/debounce; delayed shutdown after OCP events.
Schmitt Triggers
RR Schmitt-Trigger Buffer
Clear VTH+/VTH− for jitter-free edges under slow ramps.
Programmable-Hysteresis Comparator
Set hysteresis with external R/I; thresholds independent for analog-to-square conversion.
Low-Voltage CMOS Schmitt Gate
Direct logic-level interface with ultra-low power for sensor digitization.
High-Speed Schmitt Trigger
ns-class switching with strong EMI immunity for encoder/edge shaping.
Application-Focused
Fast OCP/OVP Cutoff
ns–µs response with glitch immunity; pair with eFuse/gate drivers.
PWM / Voltage-to-Frequency
Comparator + saw/triangle to synthesize duty/frequency for power/motor loops.
Zero-Cross & Phase Detection
Sync-rectification, AC metering triggers and phase comparison.
Encoder / Speed Conditioning
Schmitt shaping + debouncing with clamps for industrial/robotics.
Bridge Threshold Alarm
Use with INAs/refs for over-threshold and window alarms.
Touch / Capacitance / Conductivity Threshold
Discharge-based compare and time-to-digital schemes.
Ultrasound / ToF Echo Pick-Off
High-speed compare with programmable hysteresis for first-echo gating.
Custom Brown-In / Brown-Out
Dividers + refs for valid-power windows as a supervisor alternative.
Key Specs & Selection
Propagation Delay vs Overdrive
Small overdrive → slower; budget timing/jitter for HS chains.
Input Offset & Drift
Limits absolute threshold accuracy—critical in precision windows.
Input Common-Mode Range (VICR)
Relation to rails and crossover behavior under overdrive.
Output Type & Swing
OD vs push-pull, source/sink limits and logic-level compatibility.
Hysteresis (VHYS)
Built-in vs external; size vs noise/chatter/error trade-offs.
Power vs Speed
Iq and speed/FOM with thermal/battery-life implications.
EMI/ESD/Surge Robustness
Clamps/filters and IEC immunity—vital for outdoor/industrial.
Design Hooks
Adding Hysteresis
Compute feedback R and VTH+/VTH−; account for source-R and input bias.
Divider & Source Impedance Errors
Bias×R shifts thresholds—use lower R or buffer the source.
Slow Ramp & Chatter
Add hysteresis/RC to avoid multi-toggling on long/noisy lines.
Front-End Protection
Series-R/TVS/RC with current limits; weigh offset vs speed impacts.
Pairing with Reference/DAC
Ref noise/TC flows into thresholds—buffer/filter as needed.
Power / eFuse Co-Design
PG interactions, no-load/short criteria, fault latching and retry.
Layout & Grounding
Symmetric inputs, short loops, analog/digital split and ground-bounce control.
