SN74ALS688DWIn StockTexas Instruments
SN74ALS688DW is an 8-bit identity/magnitude comparator IC with enable input, supporting cascadable designs, 50pF load capacitance, and 24mA output. From $3.56, in stock worldwide shipping.
- Manufacturer
- Texas Instruments
- Package
- Small Outline Packages
- Pin Count
- 20
- Lifecycle
- OBSOLETE
- Datasheet
- SN74ALS688DW Datasheet PDF
- Category
- Integrated Circuit
- Price
- From $3.5640(MOQ 1)
- Temp Range
- ?°C to 70.0°C
- RoHS
- Compliant
- Lead Time
- 3–7 business days
- Shipping
- DHL Express · Worldwide
Key Features
- 8-bit identity comparator (P=Q) with active-low enable for flexible bus comparison
- Cascadable architecture allows expansion beyond 8 bits without external logic
- ALS family: Advanced Low-power Schottky technology for fast switching with low power consumption
- Supports 24mA output drive current (IOL) for reliable bus driving in TTL systems
- 20-pin SOIC (R-PDSO-G20) package optimized for compact PCB designs
Applications
The SN74ALS688DW is widely used in microprocessor address decoding, where it compares 8-bit address buses to detect specific memory or I/O locations. It is also applied in data validation circuits, industrial control systems, and CPLD/FPGA peripheral interfacing that require fast, cascadable magnitude comparison. Its enable input makes it ideal for bus arbitration and priority encoding in multi-master embedded designs.
Specifications
| YTEOL | 0 |
| Additional Feature | CASCADABLE |
| Family | ALS |
| JESD-30 Code | R-PDSO-G20 |
| JESD-609 Code | e4 |
| Load Capacitance (CL) | 50pF |
| Logic IC Type | IDENTITY COMPARATOR |
| Max I(ol) | 0.024A |
| Number of Bits | 8 |
| Number of Functions | 8 |
| Output Characteristics | TOTEM-POLE |
| Output Polarity | INVERTED |
| Package Body Material | PLASTIC/EPOXY |
| Package Equivalence Code | SOP20,.4 |
| Package Shape | RECTANGULAR |
| Package Style | SMALL OUTLINE |
| Packing Method | TUBE |
| Peak Reflow Temperature (Cel) | 260 |
| Power Supply Current-Max (ICC) | 19mA |
| Prop. Delay@Nom-Sup | 22ns |
| Propagation Delay (tpd) | 20ns |
| Qualification Status | Not Qualified |
| Supply Voltage-Max (Vsup) | 5.5V |
| Supply Voltage-Min (Vsup) | 4.5V |
| Supply Voltage-Nom (Vsup) | 5V |
| Surface Mount | YES |
| Technology | TTL |
| Temperature Grade | COMMERCIAL |
| Terminal Finish | Nickel/Palladium/Gold (Ni/Pd/Au) |
| Terminal Form | GULL WING |
| Terminal Pitch | 1.27mm |
| Terminal Position | DUAL |
| Time@Peak Reflow Temperature-Max (s) | NOT SPECIFIED |
| Package | Small Outline Packages |
Compliance & Regulatory
| RoHS Status | Compliant |
| Lead-Free | Yes (Pb-Free) |
| Moisture Sensitivity Level | MSL 1 |
| ECCN | EAR99 |
| HTS Code | 8542.39.00.60 |
| Country of Origin | Malaysia |
Alternate & Equivalent Parts
Compatible alternatives and drop-in replacements for SN74ALS688DW:
Frequently Asked Questions
What is the SN74ALS688DW and what does it do?
The SN74ALS688DW is an 8-bit identity comparator IC from Texas Instruments' ALS (Advanced Low-power Schottky) logic family. It compares two 8-bit words (P and Q) and asserts a P=Q output when all corresponding bits match. An active-low enable input allows easy bus gating and cascading for wider word comparisons.
What are the key electrical specifications of the SN74ALS688DW?
The SN74ALS688DW operates with a maximum output low current (IOL) of 24mA, a load capacitance (CL) of 50pF, and is packaged in a 20-pin SOIC (R-PDSO-G20) small outline package. It uses JESD-30 code R-PDSO-G20 and complies with JESD-609 code e4 for lead-free requirements.
How can the SN74ALS688DW be cascaded for wider comparisons?
The SN74ALS688DW supports cascading through its active-low enable input. By connecting the P=Q output of one comparator to the enable input of the next, you can compare 16-bit, 24-bit, or wider data words without additional external logic, making it ideal for scalable address decoding designs.
What are typical applications for the SN74ALS688DW?
Typical applications include microprocessor address decoding, memory bank selection, I/O port comparison, data validation in industrial controllers, and bus arbitration in embedded systems. Its 8-bit width and cascadable enable make it well-suited for TTL-compatible and mixed-logic designs requiring fast identity comparison.
What package options and alternatives are available for the SN74ALS688DW?
The SN74ALS688DW comes in a 20-pin SOIC package. Compatible alternatives within the ALS and similar logic families include the SN74ALS688N (DIP package) and functionally equivalent CMOS comparators like the 74HC688 series. Always verify voltage and timing compatibility when substituting parts in existing designs.
Related Guides
Is Buying Electronic Components from Chinese Suppliers Safe? A 2025–2026 Buyer's Guide
A 2025–2026 buyer's guide to sourcing electronic components from Chinese suppliers: real risks, authorized vs. broker channels, and a 5-point safety framework.
Apr 22, 2026
BOM Optimization: How to Reduce Electronic Component Costs Without Sacrificing Quality
Practical strategies for reducing BOM costs by 15-30% through smart component selection, supplier diversification, and procurement optimization.
Apr 9, 2026
Top 10 Microcontrollers in 2025: A Comprehensive Comparison Guide
Detailed comparison of the most popular MCUs in 2025 — STM32, ESP32, RP2040, nRF52, and more. Specs, pricing, ecosystem, and use-case recommendations.
Apr 9, 2026
How to Read an IC Datasheet: A Practical Guide for Engineers
Master the art of reading IC datasheets. Learn what every section means, which specs matter most, and how to extract the information you need for your design.
Apr 9, 2026
Why Buy from FindMyChip
About Texas Instruments
Texas Instruments (TI) is a global semiconductor company headquartered in Dallas, Texas. TI designs and manufactures analog and embedded processing chips used in industrial, automotive, consumer, communications, and enterprise systems.
| Qty. | Unit Price | Ext. Price |
|---|---|---|
| 1+ | $7.1280 | $7.13 |
| 12+ | $5.9850 | $71.82 |
| 43+ | $5.5361 | $238.05 |
| 46+ | $3.8903 | $178.95 |
| 130+ | $3.5910 | $466.83 |
| 511+ | $3.5640 | $1821.20 |
In Stock · 24h Response · Worldwide Shipping
Response within 24 hours · Worldwide shipping
“Their engineering team helped us find a pin-compatible alternative when our original MCU went EOL.”