The Original TLV3501 High-Speed Single-Supply Comparator (often referenced in Op-Amp / Signal Conditioning categories) is an ultra-fast, precision rail-to-rail I/O high-speed comparator integrated circuit manufactured by Texas Instruments. Encapsulated in a standard SOP-8 (SOIC-8) surface-mount package, it is engineered for high-frequency signal discrimination and waveform shaping applications. Featuring an exceptionally low propagation delay of just 4.5ns, a toggle frequency exceeding 80 MHz (up to 120 MHz in typical squaring circuits), and low power consumption of only 3.2mA quiescent current, the TLV3501 includes rail-to-rail CMOS/TTL-compatible push-pull outputs and built-in micro-hysteresis (approx. 6mV) to eliminate output oscillation when processing slow or noisy analog input signals. It is widely used in frequency meters, front-end zero-crossing detectors, high-speed pulse generators, time-of-flight (ToF) measurement circuits, line receivers, and clock-recovery front-ends.

Specifications

• Part Number / Model: TLV3501AID / TLV3501AIDR
• Manufacturer: Texas Instruments
• Device Function: 4.5ns Ultra-Fast Rail-to-Rail High-Speed Comparator
• Package Type: SOP-8
• Supply Voltage Range (Vcc / V+): Single Supply: 2.7V to 5.5V DC / Dual Supply: ±1.35V to ±2.75V DC
• Propagation Delay (tpd): Typ. 4.5 ns (at Overdrive = 20mV, Vcc = 5V)
• Maximum Toggle / Operating Frequency: > 80 MHz (Typ. 100 MHz to 120 MHz for small-signal shaping)
• Rise / Fall Time (tr / tf): Typ. 1.5 ns (20% to 80%, CL = 10pF)
• Output Type: Rail-to-Rail Push-Pull CMOS / TTL Compatible Output
• Input Common-Mode Voltage Range: -0.2V to (Vcc + 0.2V) (True Rail-to-Rail Input with Beyond-the-Rails headroom)
• Input Offset Voltage (Vos): Typ. ±1.0 mV / Max. ±5.0 mV (at 25°C)
• Built-in Input Hysteresis: Typ. 6 mV (Internal noise immunity threshold)
• Input Bias Current (Ib): Typ. 5 pA / Max. 50 pA (High-impedance CMOS inputs)
• Quiescent Supply Current (Iq): Typ. 3.2 mA / Max. 5.0 mA per channel (at Vcc = 5V)
• Output Short-Circuit Current (Isc): Typ. ±50 mA
• Common-Mode Rejection Ratio (CMRR): Typ. 70 dB to 80 dB
• Power Supply Rejection Ratio (PSRR): Typ. 80 dB
• Operating Ambient Temperature (Ta): -40°C to +125°C
• Storage Temperature Range (Tstg): -65°C to +150°C
• Pinout Configuration:
  • Pin 1: No Connection (NC) / Shutdown (on specific variants)
  • Pin 2: Inverting Input (IN-)
  • Pin 3: Non-Inverting Input (IN+)
  • Pin 4: Negative Supply / Ground (V- / GND)
  • Pin 5: No Connection (NC)
  • Pin 6: Output (OUT)
  • Pin 7: Positive Supply (V+ / VCC)
  • Pin 8: No Connection (NC)

Features

• 4.5ns Ultra-High-Speed Response: Fast propagation delay enables accurate zero-crossing detection, high-frequency squaring, and sub-nanosecond pulse discrimination up to 100+ MHz.
• Rail-to-Rail Input & Push-Pull Output: Accommodates input voltages spanning ground up to the positive supply rail, while the push-pull output drives TTL, CMOS, and high-speed MCU/FPGA inputs directly without an external pull-up resistor.
• Built-in 6mV Hysteresis: Integrated internal hysteresis prevents false triggering, multiple transitions, and output chatter caused by slow-moving analog signals or high-frequency input noise.
• Ultra-Low 5pA Input Bias: CMOS input stage presents virtually no loading to upstream high-impedance sensors, RF detectors, and tuned LC resonant tanks.
• Single-Supply 2.7V to 5.5V Flexibility: Seamlessly runs from 3.3V logic rails (STM32, ESP32, FPGA) or 5.0V systems (Arduino, 5V TTL systems) with no voltage level shifting required.

Common Applications

• High-Speed Frequency Counters & Meters: Front-end small-signal conditioning to square sine, triangle, and weak RF signals before feeding MCU timer capture pins.
• Laser Rangefinders & Time-of-Flight (ToF): Ultra-fast pulse timing discrimination for optical echo detection circuits.
• Clock Recovery & Waveform Squaring: Converting low-amplitude oscillator sine waves into clean square clock pulses with sub-nanosecond jitter.
• Zero-Crossing Detectors & Phase Meters: Precision AC zero-cross detection in power monitoring and phase angle calculation units.
• High-Speed Line Receivers: Differential and single-ended high-speed data transmission over twisted-pair cables.

Usage Tips

• Comparator vs. Op-Amp Functionality: Note that although frequently categorized alongside operational amplifiers due to its pinout, the TLV3501 is a dedicated **high-speed digital output comparator** and is not intended for linear negative feedback amplification circuits.
• Power Rail Decoupling: Due to sub-nanosecond edge rates (tr ≈ 1.5ns), high switching transients occur during state transitions. Always place a **100nF low-ESR ceramic capacitor in parallel with a 10µF tantalum/ceramic capacitor** directly between Pin 7 (V+) and Pin 4 (GND) with minimal trace length.
• Adding External Positive Hysteresis: For very noisy or millivolt-level slow signals, add external positive feedback (a 100kΩ to 1MΩ resistor between Pin 6 Output and Pin 3 Non-Inverting Input, paired with a small input series resistor) to widen the hysteresis band and prevent parasitic oscillation.
• Keep Input & Output Traces Isolated: Route high-speed output lines (Pin 6) far away from sensitive high-impedance input pins (Pin 2 and Pin 3) to prevent capacitive coupling and self-oscillation at frequencies above 50 MHz.
• Impedance Matching on Long Cables: If routing the Pin 6 output over coaxial cable or PCB transmission lines longer than a few inches, place a 50Ω series resistor at the comparator output to match transmission line characteristic impedance and suppress ringing.

Datasheet