My Inquiry
My Account
NXP Semiconductors 74HCT688PW,118
- Part No.:
- 74HCT688PW,118
- Manufacturer:
- NXP Semiconductors
- Category:
- Comparators
- Package:
- 20-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
74HCT688PW,118.pdf
- Description:
- IC COMPARATOR IDENTITY 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,245
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
74HCT688PW,118 from Nexperia is an 8-bit magnitude comparator IC that compares two 8-bit binary or BCD words and asserts a single active-HIGH P = Q output when inputs match. It operates at 4.5 V to 5.5 V, delivers 17 ns typical propagation delay (Pn/Qn → P = Q), and features TTL-compatible input thresholds. It is used in digital systems requiring word equality detection, such as address decoding in microprocessor buses.
For engineers reviewing the 74HCT688PW,118 datasheet, 74HCT688PW,118 pinout, 74HCT688PW,118 application, or 74HCT688PW,118 equivalent, key selection criteria include enable-controlled comparison timing, HCT-level input compatibility with legacy TTL logic, low-power CMOS operation, and TSSOP-20 packaging for high-density PCB layouts.
Technical Context
The 74HCT688PW,118 implements combinational logic for bitwise equality evaluation across eight parallel input pairs (P₀–P₇ and Q₀–Q₇), with an active-LOW enable (E) controlling output assertion. Its output stage drives standard CMOS loads with ±4 mA output current capability at VCC = 4.5 V.
Propagation delays are asymmetric: E-to-output delay (12 ns typ.) is faster than data-input-to-output delay (17 ns typ.), enabling precise timing control in cascaded comparator configurations. The device conforms to JEDEC Standard No. 7A and supports operation from −40 °C to +125 °C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - ensures interoperability with 5 V TTL and mixed-signal systems |
| tPHL/tPLH (Pn/Qn → P = Q) | 17 ns typical at VCC = 5 V, CL = 15 pF - defines maximum clock rate for synchronous equality checks |
| tPHL/tPLH (E → P = Q) | 12 ns typical at VCC = 5 V, CL = 15 pF - enables fast enable-gated comparison windows |
| Input Threshold (HCT) | VIH = 2.0 V min, VIL = 0.8 V max - guarantees reliable interfacing with 5 V TTL outputs |
| Output Drive | ±4 mA at VCC = 4.5 V - supports fan-out of ≥10 74HCT inputs without buffering |
| Power Dissipation Cap. (CPD) | 30 pF - used to calculate dynamic power: PD = CPD × VCC² × fi + Σ(CL × VCC² × fo) |
Pinout & Package
74HCT688PW,118 is housed in a 20-pin TSSOP (Thin Shrink Small Outline Package) with 0.65 mm pitch, optimized for automated assembly and space-constrained PCBs. Pin 1 is marked by a beveled corner or dot; pin numbering follows standard counter-clockwise convention from the mark.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | E | Active-LOW enable - output P = Q is only valid when E = LOW |
| 2,4,6,8,11,13,15,17 | P₀–P₇ | First 8-bit operand inputs - must be driven with valid logic levels before enable activation |
| 3,5,7,9,12,14,16,18 | Q₀–Q₇ | Second 8-bit operand inputs - matched pin order to P₀–P₇ for symmetrical layout routing |
| 10 | GND | Ground reference - requires low-inductance connection to minimize switching noise |
| 19 | P = Q | Active-HIGH equality output - asserted HIGH only when E = LOW and all eight Pn = Qn |
| 20 | VCC | Positive supply - bypassed with 100 nF ceramic capacitor near pin for stable operation |
Key Features
| Feature | Design Value |
|---|---|
| TTL-compatible inputs | Guarantees direct interface with legacy 74LS/74ALS logic without level-shifting circuitry |
| Enable-controlled output | Allows time-multiplexed comparison of multiple word pairs using shared P = Q bus |
| Low quiescent current | Typical ICC = 4 µA at VCC = 5 V, TA = 25 °C - reduces standby power in battery-backed systems |
| Cascadable architecture | Supports multi-word comparisons (e.g., 16-bit, 24-bit) via P = Q chaining without external gates |
Applications
| Microprocessor Address Decoding | Memory-Mapped I/O Selection |
|---|---|
Use Scenario: Detecting exact matches between CPU address bus and peripheral base addresses in 8-bit embedded systems. IC Role / Device Role / Timing Role: 74HCT688PW,118 acts as a dedicated address comparator, asserting chip-select when P₀–P₇ and Q₀–Q₇ align with decoded address bits. Use Value: Eliminates need for discrete NAND/NOR gate networks, reducing component count and propagation delay in decode paths. | Use Scenario: Selecting specific I/O registers within a peripheral device mapped across consecutive 8-bit address locations. IC Role / Device Role / Timing Role: 74HCT688PW,118 compares latched address bits against fixed register offsets, enabling precise register access control. Use Value: Provides deterministic, glitch-free selection with sub-20 ns response-critical for synchronous I/O handshaking. |
| BCD-Based Display Control | Cascaded Word Comparison |
Use Scenario: Validating numeric entry in BCD-encoded keypad interfaces before driving 7-segment displays. IC Role / Device Role / Timing Role: 74HCT688PW,118 verifies equality between entered BCD digits and stored reference values in real time. Use Value: Ensures accurate digit matching without software overhead, supporting low-latency visual feedback. | Use Scenario: Building 16-bit or 24-bit comparators for industrial motion controllers requiring extended word-length evaluation. IC Role / Device Role / Timing Role: 74HCT688PW,118 serves as a modular building block, with P = Q outputs chained to enable downstream comparators. Use Value: Enables scalable, deterministic comparison depth while maintaining consistent timing margins across stages. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 8-bit magnitude comparator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HCT688N | Dual-in-line package (PDIP-20); higher thermal resistance; no moisture sensitivity level rating | Suitable for prototyping and through-hole assembly; less suitable for reflow-soldered high-density boards | Select when manual soldering or breadboard validation is required |
| 74HCT688D,653 | SO-20 package; identical AC/DC specs; slightly higher tPHL/tPLH (18 ns vs. 17 ns typ. for Pn/Qn path) | Compatible with wave-solder processes; lower profile than TSSOP but larger footprint | Select when SO-20 footprint compatibility or legacy board reuse is prioritized |
Compared with SN74HCT688N and 74HCT688D,653, the 74HCT688PW,118 offers superior thermal performance and board-area efficiency in surface-mount designs, with identical functional behavior and timing-making it optimal for volume production of compact, thermally constrained electronics.
Availability
74HCT688PW,118 is available at Aetrix Electronics and suitable for microprocessor address decoding, memory-mapped I/O selection, BCD-based display control, and cascaded word comparison requiring stable component supply across automotive, industrial, and computing applications.
Supply support for 74HCT688PW,118 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
Nexperia is a global semiconductor leader specializing in high-performance, energy-efficient discrete, logic, and power MOSFET solutions for automotive, industrial, computing, and consumer markets.
The 74HCT688PW,118 belongs to Nexperia's 74HCT logic family, engineered for seamless integration with legacy TTL systems while delivering CMOS power efficiency and robust noise immunity in industrial-grade environments.
FAQ
What is the function of the E pin on the 74HCT688PW,118?
The E pin on the 74HCT688PW,118 is an active-LOW enable input. When E is HIGH, the P = Q output is forced LOW regardless of input states. Only when E is LOW does the device evaluate P₀–P₇ and Q₀–Q₇ for equality. This allows time-gated comparison and supports cascading multiple 74HCT688PW,118 devices in wider-word systems.
Does the 74HCT688PW,118 support BCD comparison?
Yes, the 74HCT688PW,118 supports both binary and BCD word comparison. Its internal logic performs bitwise equivalence checking without encoding assumptions, making it suitable for BCD-based applications like keypad validation and display decoding where decimal digit alignment matters.
What is the maximum operating temperature for the 74HCT688PW,118?
The 74HCT688PW,118 is rated for operation from −40 °C to +125 °C. This extended industrial temperature range is confirmed in the AC characteristics tables and supports deployment in under-hood automotive modules, motor drives, and factory automation equipment where ambient thermal stress is significant.
Can the 74HCT688PW,118 be used in 3.3 V systems?
No, the 74HCT688PW,118 is not specified for 3.3 V operation. Its HCT input thresholds and AC performance are validated only at VCC = 4.5 V to 5.5 V. For 3.3 V logic systems, consider the 74LVC688 or other LVC-family comparators with compatible voltage rails and thresholds.
Is the 74HCT688PW,118 pin-compatible with older NXP or Philips versions?
Yes, the 74HCT688PW,118 maintains full pin, function, and timing compatibility with original Philips Semiconductors and NXP 74HCT688 devices in TSSOP-20 packaging. Nexperia retained identical electrical specifications, pinout, and mechanical dimensions per the 74HC/HCT logic family standards.
74HCT688PW,118 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- 74HCT
- Package/Case:
- 20-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- Identity Comparator
- Number of Bits:
- 8
- Output:
- Active Low
- Output Function:
- A=B
- Voltage - Supply:
- 4.5V ~ 5.5V
- Current - Output High, Low:
- 4mA, 4mA
- Max Propagation Delay @ V, Max CL:
- 34ns @ 4.5V, 50pF
- Current - Quiescent (Iq):
- 8 µA
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 20-TSSOP
- Mounting Type:
- Surface Mount
74HCT688PW,118 FAQ
1.How can I place an order for 74HCT688PW,118 through Aetrix?
Please submit a Request for Quotation (RFQ) for 74HCT688PW,118 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 74HCT688PW,118 reliable?
The price and inventory of 74HCT688PW,118 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74HCT688PW,118 is usually 5 days.
3.What payment methods are accepted for 74HCT688PW,118?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74HCT688PW,118 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 74HCT688PW,118?
74HCT688PW,118 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 74HCT688PW,118 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 74HCT688PW,118?
For technical support, including 74HCT688PW,118 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74HCT688PW,118 requirements.
6.How does Aetrix verify that 74HCT688PW,118 is sourced from the original manufacturer or authorized distributors?
All 74HCT688PW,118 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 74HCT688PW,118 meets industry standards.
7.What is the process for return or replacement of 74HCT688PW,118?
All 74HCT688PW,118 units undergo pre-shipment inspection (PSI). If there is an issue with 74HCT688PW,118, 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 74HCT688PW,118 part is unused and in its original packaging.
Return procedure for 74HCT688PW,118:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
74HCT688PW,118 Tags
-
SN74HC688PWR
Texas Instruments
-
74HC85PW,118
Nexperia USA Inc.
-
74HC688D,653
Nexperia USA Inc.
-
SN74F521DWR
Texas Instruments
-
CD74HCT688M96
Texas Instruments
-
SN74F521N
Texas Instruments
-
CD4585BE
Texas Instruments
-
SN74HC688DWR
Texas Instruments
-
SN74LS85DR
Texas Instruments
-
CD74HC85E
Texas Instruments
-
MC14585BDR2G
onsemi
-
SN74HC688N
Texas Instruments
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
