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NXP Semiconductors 74HC688N,652
- Part No.:
- 74HC688N,652
- Manufacturer:
- NXP Semiconductors
- Category:
- Comparators
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
74HC688N,652.pdf
- Description:
- IC COMPARATOR IDENTITY 8B 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,843
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Product details
Overview
74HC688N,652 from Nexperia is an 8-bit magnitude comparator IC performing binary or BCD word comparison with active-low enable (E), P=Q output, and clamp diodes for overvoltage-tolerant input interfacing. It operates from 2.0 V to 6.0 V supply, delivers propagation delays as low as 8 ns at VCC = 6.0 V, and supports industrial temperature range up to +125 °C. It is used in digital logic systems requiring precise equality detection between parallel data words.
For engineers reviewing the 74HC688N,652 datasheet, 74HC688N,652 pinout, 74HC688N,652 application, or 74HC688N,652 equivalent, key selection factors include its 20-pin SO20 package, CMOS-level compatibility, low-power static operation (≤160 μA ICC), and cascading capability for multi-word comparisons.
Technical Context
The 74HC688N,652 implements a combinatorial 8-bit equality comparator with synchronous enable control: only when E is LOW does the P=Q output reflect the bitwise equivalence of the two 8-bit inputs (P₀–P₇ and Q₀–Q₇). Its internal logic uses NAND/NOR-based gate arrays optimized for speed-power trade-off across voltage ranges.
Input clamping diodes allow safe interface to signals exceeding VCC when current-limiting resistors are used; output drive strength is ±4.0 mA at VCC = 4.5 V (VOH ≥ 3.98 V, VOL ≤ 0.26 V), ensuring robust fan-out to downstream HC/HCT logic. Propagation delay varies predictably with supply voltage and load capacitance (CL = 50 pF).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Function | 8-bit magnitude comparator with active-low enable and single P=Q output |
| Supply Voltage Range | 2.0 V to 6.0 V - enables direct interface with 3.3 V and 5 V logic domains |
| Propagation Delay (Pn/Qn → P=Q) | 16 ns typical at VCC = 6.0 V, CL = 50 pF - determines maximum clock rate in pipelined comparators |
| Input Voltage Thresholds | VIH = 4.2 V, VIL = 1.8 V at VCC = 6.0 V - ensures noise margin >1.2 V in 5 V systems |
| Output Drive Capability | ±4.0 mA at VCC = 4.5 V - supports driving ≥10 HC loads or one HCT buffer stage |
| Operating Temperature | −40 °C to +125 °C - qualified for extended industrial environments without derating |
| ESD Protection | HBM >2000 V, CDM >1000 V - reduces need for external protection in board-level ESD zones |
Pinout & Package
74HC688N,652 is supplied in the SOT146-1 package - a 20-lead plastic dual in-line package (PDIP) with 0.3-inch body width and standard through-hole mounting footprint. Pin spacing is 0.1 inch (2.54 mm), compatible with legacy PCB layouts and socketing.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (E) | Enable input | Active-LOW control: P=Q output is valid only when E = LOW; HIGH forces P=Q = HIGH regardless of inputs |
| 2,4,6,8,11,13,15,17 (P0–P7) | Word P data inputs | Parallel 8-bit input bus for first operand; CMOS-compatible thresholds and clamp diodes permit overvoltage-safe interfacing |
| 3,5,7,9,12,14,16,18 (Q0–Q7) | Word Q data inputs | Parallel 8-bit input bus for second operand; electrically identical to P inputs |
| 10 (GND) | Ground reference | 0 V return path for all internal logic and I/O; must be low-impedance for stable noise immunity |
| 19 (P=Q) | Equality output | Open-drain compatible HIGH/LOW signal indicating full 8-bit match; sinks current when LOW, pulls HIGH via internal weak pull-up when enabled |
| 20 (VCC) | Supply voltage | Primary power rail (2.0–6.0 V); decoupling capacitor (100 nF) required within 10 mm for stable high-speed operation |
Key Features
| Feature | Design Value |
|---|---|
| Wide supply voltage range | 2.0 V to 6.0 V operation enables drop-in replacement across 3.3 V and 5 V logic families without level-shifting |
| Input clamp diodes | Integrated protection allows safe interface to signals up to VCC + 0.5 V using external current-limiting resistors |
| High noise immunity | Guaranteed 1.2 V noise margin at VCC = 6.0 V ensures reliable operation in electrically noisy industrial cabinets |
| Latch-up immunity | Exceeds 100 mA per JESD78 Class II Level B - eliminates risk of destructive latch-up under transient overvoltage |
| Cascadable architecture | Multiple 74HC688N,652 devices can be chained to compare 16-, 24-, or 32-bit words using P=Q outputs as enable signals |
Applications
| Industrial PLC I/O Mapping | Digital Panel Meter Calibration |
|---|---|
Use Scenario: Comparing real-time sensor register values against programmable setpoints in ladder-logic execution cycles. IC Role / Device Role / Timing Role: 74HC688N,652 acts as a cycle-synchronized equality detector feeding status bits into the PLC's scan engine. Use Value: Enables deterministic response within one instruction cycle due to sub-20 ns propagation delay at 5 V, reducing scan jitter in time-critical motion control. | Use Scenario: Validating ADC output codes against known reference values during self-test or factory calibration sequences. IC Role / Device Role / Timing Role: 74HC688N,652 serves as a pass/fail comparator in microcontroller-driven calibration firmware, asserting fault flags on mismatch. Use Value: Low quiescent current (≤160 μA) minimizes power impact during infrequent calibration routines, extending battery life in portable meters. |
| Legacy Bus Arbitration Logic | Secure Bootloader Integrity Check |
Use Scenario: Detecting address matches between CPU address bus and peripheral decode windows in retro-computing or embedded controller designs. IC Role / Device Role / Timing Role: 74HC688N,652 functions as a fast, glueless address comparator enabling zero-wait-state memory-mapped I/O decoding. Use Value: 8 ns min. propagation delay at 6 V allows reliable operation at CPU clock rates up to 25 MHz without timing closure issues. | Use Scenario: Verifying cryptographic hash outputs against stored golden values during secure boot initialization before code execution. IC Role / Device Role / Timing Role: 74HC688N,652 performs constant-time equality check on 64-bit hash segments, preventing timing side-channel leakage. Use Value: Deterministic combinatorial logic (no internal state) ensures identical delay regardless of input pattern - critical for side-channel-resistant verification. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 8-bit comparator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LS688N | TTL logic family; 4.75–5.25 V only; higher ICC (40 mA typical); slower (35 ns max) | Requires 5 V supply only; not suitable for mixed-voltage or low-power systems | Select only if maintaining legacy TTL bus compatibility and higher power budget is acceptable |
| 74HCT688N,652 | CMOS input thresholds matched to TTL levels (VIH = 2.0 V min); otherwise identical pinout and function | Better interoperability with 5 V TTL outputs without level shifters; same SO20 package | Prefer when interfacing directly to legacy 5 V TTL drivers where 74HC688N,652 may misread marginal HIGHs |
Compared with SN74LS688N, the 74HC688N,652 offers 3× lower power and 2× faster speed but requires careful input threshold alignment; versus 74HCT688N,652, it trades TTL-input compatibility for slightly better noise margin in pure CMOS systems.
Availability
74HC688N,652 is available at Aetrix Electronics and suitable for industrial PLC I/O mapping, digital panel meter calibration, legacy bus arbitration logic, and secure bootloader integrity checks requiring stable component supply across long-lifecycle programs.
Supply support for 74HC688N,652 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 expert specializing in high-performance, energy-efficient logic, analog, and discrete components for automotive, industrial, and consumer applications.
The 74HC688N,652 belongs to Nexperia's 74HC logic family - designed for low-power, high-noise-immunity digital interfacing in extended-temperature industrial control and instrumentation systems.
FAQ
What is the operating temperature range supported by the 74HC688N,652?
The 74HC688N,652 is specified for operation from −40 °C to +125 °C, meeting extended industrial requirements. This rating is validated per JEDEC JESD7A and confirmed in the datasheet's Recommended Operating Conditions table (Tamb = −40 °C to +125 °C), with no derating needed up to the upper limit.
Does the 74HC688N,652 support cascading for comparing more than 8 bits?
Yes, the 74HC688N,652 supports cascading: its P=Q output can drive the E (enable) input of a downstream 74HC688N,652 to build 16-bit or wider comparators. The datasheet provides Fig. 7 showing this exact configuration for binary or BCD numbers exceeding 8 bits.
What is the maximum propagation delay of the 74HC688N,652 at 5 V supply?
At VCC = 5.0 V with CL = 15 pF, the 74HC688N,652 has a typical propagation delay of 17 ns (Pn/Qn to P=Q) and 8 ns (E to P=Q), with maximum values of 34 ns and 24 ns respectively, as specified in Table 7 of the Rev. 5 datasheet.
Can the 74HC688N,652 inputs tolerate voltages above VCC?
Yes - the 74HC688N,652 includes integrated input clamp diodes. When used with external current-limiting resistors, inputs can safely accept voltages up to VCC + 0.5 V, as defined in Table 4 (Limiting Values) and confirmed in Section 1 General Description.
Is the 74HC688N,652 pin-compatible with the 74HCT688N,652?
Yes - the 74HC688N,652 and 74HCT688N,652 share identical pinout, package (SOT146-1), and functional behavior. The sole difference is input voltage thresholds: 74HCT688N,652 accepts TTL-level inputs (VIH ≥ 2.0 V), while 74HC688N,652 requires CMOS-level inputs (VIH ≥ 4.2 V at VCC = 6.0 V).
74HC688N,652 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- 74HC
- Package/Case:
- 20-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Type:
- Identity Comparator
- Number of Bits:
- 8
- Output:
- Active Low
- Output Function:
- A=B
- Voltage - Supply:
- 2V ~ 6V
- Current - Output High, Low:
- 5.2mA, 5.2mA
- Max Propagation Delay @ V, Max CL:
- 29ns @ 6V, 50pF
- Current - Quiescent (Iq):
- 8 µA
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 20-DIP
- Mounting Type:
- Through Hole
74HC688N,652 FAQ
1.How can I place an order for 74HC688N,652 through Aetrix?
Please submit a Request for Quotation (RFQ) for 74HC688N,652 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 74HC688N,652 reliable?
The price and inventory of 74HC688N,652 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74HC688N,652 is usually 5 days.
3.What payment methods are accepted for 74HC688N,652?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74HC688N,652 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 74HC688N,652?
74HC688N,652 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 74HC688N,652 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 74HC688N,652?
For technical support, including 74HC688N,652 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74HC688N,652 requirements.
6.How does Aetrix verify that 74HC688N,652 is sourced from the original manufacturer or authorized distributors?
All 74HC688N,652 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 74HC688N,652 meets industry standards.
7.What is the process for return or replacement of 74HC688N,652?
All 74HC688N,652 units undergo pre-shipment inspection (PSI). If there is an issue with 74HC688N,652, 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 74HC688N,652 part is unused and in its original packaging.
Return procedure for 74HC688N,652:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
74HC688N,652 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
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