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Analog Devices Inc. LT1721CGN#PBF
- Part No.:
- LT1721CGN#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Comparators
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LT1721CGN#PBF.pdf
- Description:
- IC COMPARATOR 4 GEN PUR 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:130
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Product details
Overview
LT1721CGN#PBF from Analog Devices (formerly Linear Technology) is a quad ultrafast comparator optimized for single-supply 3V/5V operation, delivering 4.5ns propagation delay at 20mV overdrive, rail-to-rail TTL/CMOS-compatible outputs, and internal 3.5mV hysteresis. It operates from 2.7V to 6V, supports input voltages down to 100mV below ground, and targets high-speed threshold detection in crystal oscillator circuits, window comparators, and pulse stretching applications.
For engineers reviewing the LT1721CGN#PBF datasheet, LT1721CGN#PBF pinout, LT1721CGN#PBF application, or LT1721CGN#PBF equivalent, key selection criteria include guaranteed 4.5ns speed at 20mV overdrive, low 4mA per comparator supply current, 16-pin narrow SSOP package with validated pin isolation for high-speed layout, and differential propagation delay under 1.0ns across channels.
Technical Context
The LT1721CGN#PBF implements a complementary bipolar input stage with internal hysteresis, enabling stable operation with slow-moving signals without external feedback. Its pinout places inverting inputs (–IN A/B/C/D) away from outputs and shields them with VCC/GND rails to minimize parasitic coupling-critical for sub-5ns timing integrity.
Each of the four independent comparators features rail-to-rail output drive capable of sourcing 4mA and sinking 10mA while maintaining VOH ≥ VCC – 0.4V and VOL ≤ 0.4V. The device exhibits 10μV/°C input offset drift and maintains <1.0ns differential propagation delay between channels over temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Propagation Delay | 4.5ns typical at 20mV overdrive - enables reliable sampling of >200MHz digital edges |
| Supply Voltage Range | 2.7V to 6V - supports direct interface with 3.3V and 5V logic domains without level shifters |
| Input Common Mode Range | –0.1V to VCC – 1.2V - allows detection of signals below ground in single-supply systems |
| Output Drive | Rail-to-rail, TTL/CMOS compatible - directly drives 74HC/LVC logic without pull-ups or buffers |
| Supply Current | 4mA per comparator at 5V - total 16mA for full quad operation, suitable for power-constrained designs |
| Hysteresis Voltage | 3.5mV typical - prevents chatter on noisy or slowly varying inputs without external components |
| Differential Propagation Delay | ≤1.0ns - ensures matched timing across all four comparators for synchronized decision logic |
Pinout & Package
LT1721CGN#PBF is housed in a 16-lead narrow plastic SSOP (GN package), 5.3mm × 6.2mm body, 0.65mm pitch, with exposed thermal pad internally connected to GND. Pin 1 is –IN A; pins 3 and 6 are GND; pins 11 and 14 are VCC; pin 16 is –IN D.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (–IN A) | Inverting input of Comparator A | Most sensitive node; placed opposite outputs and shielded by adjacent VCC/GND pins to reduce crosstalk |
| 2 (+IN A) | Noninverting input of Comparator A | Paired with Pin 1; differential pair forms high-gain front-end with 10μV/°C offset drift |
| 3, 6 (GND) | Ground reference | Both pins must be externally shorted to ensure proper shielding and low-impedance return path |
| 4 (OUT A) | Output of Comparator A | Rail-to-rail CMOS/TTL driver; sinks 10mA min, sources 4mA min into 10pF load |
| 5 (OUT B) | Output of Comparator B | Electrically isolated from OUT A; differential skew <1.5ns ensures synchronous edge alignment |
| 7 (+IN B) | Noninverting input of Comparator B | Positioned adjacent to VCC (Pin 8) to maintain input rail shielding integrity |
| 8 (–IN B) | Inverting input of Comparator B | Placed opposite OUT B (Pin 5); layout minimizes capacitive coupling to output nodes |
| 9 (–IN C) | Inverting input of Comparator C | Part of second comparator pair; shares same shielding strategy as Pins 1 and 8 |
| 10 (+IN C) | Noninverting input of Comparator C | Paired with Pin 9; identical electrical specs to +IN A/B/D |
| 11, 14 (VCC) | Positive supply | Both pins electrically shorted internally but must be externally tied to ensure full rail shielding |
| 12 (OUT C) | Output of Comparator C | Drives same logic families as OUT A/B; rise/fall times ≤2.5ns/2.2ns into 10pF |
| 13 (OUT D) | Output of Comparator D | Final output; matches propagation delay spec of 4.5ns typ. at 20mV overdrive |
| 15 (+IN D) | Noninverting input of Comparator D | Completes fourth input pair; positioned to maintain symmetry with other +IN terminals |
| 16 (–IN D) | Inverting input of Comparator D | Terminates input shielding sequence; adjacent to GND (Pin 3) and VCC (Pin 14) |
Key Features
| Feature | Design Value |
|---|---|
| Ultrafast 4.5ns propagation delay | Enables accurate timing capture of fast digital transitions without added latency in clock recovery or data slicing |
| Internal 3.5mV hysteresis | Eliminates need for external positive feedback resistors in threshold detection, reducing BOM count and layout area |
| Rail-to-rail TTL/CMOS outputs | Directly interfaces with 74LVC, 74AHC, and microcontroller GPIOs without level-shifting circuitry |
| Input range extends 100mV below ground | Supports AC-coupled signal detection and negative-going edge triggering in single-supply systems |
| Quad independent comparators | Allows implementation of multi-level window detection, dual-edge zero-crossing, or redundant safety monitoring in one IC |
Applications
| Crystal Oscillator Circuit | Window Comparator |
|---|---|
Use Scenario: Used in Pierce oscillator configurations with AT-cut crystals operating from 1MHz to 10MHz, providing clean square-wave output with minimal jitter. IC Role / Device Role / Timing Role: Acts as high-gain, low-delay amplifier sustaining crystal oscillation and shaping output waveform. Use Value: 4.5ns propagation delay and 15psRMS timing jitter preserve oscillator phase stability and reduce EMI in clock distribution networks. | Use Scenario: Monitors analog sensor output (e.g., temperature, pressure) against upper and lower thresholds to trigger alarms or control actions. IC Role / Device Role / Timing Role: Implements dual-threshold comparison using two comparators per channel with shared hysteresis. Use Value: Internal 3.5mV hysteresis prevents false triggering near trip points; rail-to-rail outputs directly drive microcontroller interrupt pins. |
| High-Speed Pulse Stretcher | Zero-Crossing Detector |
Use Scenario: Extends narrow pulses from optical encoders or RF detectors to meet minimum width requirements of downstream logic or ADC sampling windows. IC Role / Device Role / Timing Role: Configured with RC network and internal hysteresis to generate fixed-duration output pulses from fast input edges. Use Value: Sub-5ns delay ensures precise pulse start timing; 16mA peak output drive sustains pulse integrity into 50Ω loads. | Use Scenario: Detects polarity reversal of AC line voltage or audio signals for synchronization, rectification control, or phase-locked loops. IC Role / Device Role / Timing Role: Compares sinusoidal input against 0V reference with fast response to both rising and falling zero crossings. Use Value: Input common mode range extending 100mV below ground enables true 0V detection without biasing; 7ns delay at 5mV overdrive captures fine zero-crossing detail. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar quad high-speed comparator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM393AQDRQ1 | Slower (1.3μs propagation delay), open-collector outputs, no internal hysteresis, automotive-grade (-40°C to 125°C) | Suitable only for low-speed DC threshold detection; requires external pull-up and hysteresis resistors | Select only when cost sensitivity outweighs speed and integration needs; not viable for crystal oscillator or pulse-stretching use cases |
| MAX961ESA+ | 4.5ns delay (same), but dual-channel only, SO-8 package, higher 8mA supply current per comparator | Limited to two-channel functions; lacks quad integration needed for window or multi-edge detection | Choose when board space is constrained and only two comparators are required; avoid when four independent channels are essential |
Compared with LM393AQDRQ1 and MAX961ESA+, the LT1721CGN#PBF uniquely delivers quad-channel 4.5ns performance with integrated hysteresis and rail-to-rail outputs in a single 16-pin SSOP-enabling compact, high-fidelity timing and threshold functions unachievable with either alternative.
Availability
LT1721CGN#PBF is available at Aetrix Electronics and suitable for crystal oscillator circuits, window comparators, high-speed pulse stretchers, and zero-crossing detectors requiring stable component supply and consistent parametric performance across production batches.
Supply support for LT1721CGN#PBF includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Analog Devices, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing technologies, serving industrial, automotive, communications, and healthcare markets.
The LT1721CGN#PBF belongs to ADI's legacy Linear Technology high-speed comparator product line, designed specifically for precision timing, threshold detection, and signal conditioning in single-supply systems where speed, low power, and integration are critical.
FAQ
What is the maximum toggle frequency supported by the LT1721CGN#PBF?
The LT1721CGN#PBF supports a maximum toggle frequency of 70.0MHz at 3V supply and 62.5MHz at 5V supply when driven with 50mV overdrive. This is derived from its 4.5ns propagation delay and internal architecture, making it suitable for high-speed data slicing and clock regeneration tasks where precise edge placement is required. The LT1721CGN#PBF maintains this performance across its full operating temperature range (0°C to 70°C).
Does the LT1721CGN#PBF require external hysteresis resistors for stable operation?
No, the LT1721CGN#PBF includes internal hysteresis of 3.5mV typical, which eliminates the need for external positive feedback components in most threshold-detection applications. This built-in hysteresis stabilizes output behavior with slow-moving or noisy inputs. The LT1721CGN#PBF datasheet confirms hysteresis is specified and tested across temperature, and external hysteresis is only recommended when additional margin beyond 3.5mV is required.
Can the LT1721CGN#PBF operate from a 3.3V supply?
Yes, the LT1721CGN#PBF is fully specified to operate from 2.7V to 6V, including standard 3.3V logic supplies. At 3.3V, it delivers 4.5ns propagation delay (typical), rail-to-rail outputs swinging within 400mV of rails, and 4mA supply current per comparator. All electrical characteristics-including input common mode range (–0.1V to 2.1V) and hysteresis-are guaranteed across this voltage range, making the LT1721CGN#PBF ideal for modern low-voltage embedded systems.
How does the LT1721CGN#PBF handle input signals below ground?
The LT1721CGN#PBF supports input voltages down to 100mV below ground (VCM = –0.1V) while maintaining valid output polarity and specified propagation delay. If both inputs fall below this limit, phase reversal protection holds output logic state to at least –400mV, though offset and hysteresis increase. For robust sub-ground operation, external Schottky clamps are recommended to prevent substrate diode conduction. This capability makes the LT1721CGN#PBF suitable for true zero-crossing detection without input biasing.
What is the thermal performance of the LT1721CGN#PBF in the GN package?
The LT1721CGN#PBF in the 16-lead narrow SSOP (GN) package has a junction-to-ambient thermal resistance (θJA) of 135°C/W and a maximum junction temperature (TJMAX) of 150°C. With its exposed thermal pad internally connected to GND, optimal PCB layout-using multiple vias to an internal ground plane-reduces effective θJA. At full quad operation (16mA total ICC), power dissipation is ~80mW at 5V, resulting in ~10.8°C junction-to-ambient rise above ambient-well within safe operating limits for industrial environments.
LT1721CGN#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Package/Case:
- 16-SSOP (0.154", 3.90mm Width)
- Series:
- UltraFast™
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- General Purpose
- Number of Elements:
- 4
- Output Type:
- CMOS, Rail-to-Rail, TTL
- Voltage - Supply, Single/Dual (±):
- 2.7V ~ 6V
- :
- 3mV @ 5V
- Voltage - Input Offset (Max):
- 6µA @ 5V
- Current - Input Bias (Max):
- 20mA
- Current - Output (Typ):
- 7mA
- Current - Quiescent (Max):
- 70dB CMRR, 80dB PSRR
- CMRR, PSRR (Typ):
- 10ns
- Propagation Delay (Max):
- 7mV
- Hysteresis:
- 0°C ~ 70°C
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- Surface Mount
- :
- 16-SSOP
LT1721CGN#PBF FAQ
1.How can I place an order for LT1721CGN#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1721CGN#PBF on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LT1721CGN#PBF reliable?
The price and inventory of LT1721CGN#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1721CGN#PBF is usually 5 days.
3.What payment methods are accepted for LT1721CGN#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1721CGN#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1721CGN#PBF?
LT1721CGN#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1721CGN#PBF order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LT1721CGN#PBF?
For technical support, including LT1721CGN#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1721CGN#PBF requirements.
6.How does Aetrix verify that LT1721CGN#PBF is sourced from the original manufacturer or authorized distributors?
All LT1721CGN#PBF products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LT1721CGN#PBF meets industry standards.
7.What is the process for return or replacement of LT1721CGN#PBF?
All LT1721CGN#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1721CGN#PBF, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LT1721CGN#PBF part is unused and in its original packaging.
Return procedure for LT1721CGN#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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