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NXP Semiconductors 74HCT640D,653
- Part No.:
- 74HCT640D,653
- Manufacturer:
- NXP Semiconductors
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
74HCT640D,653.pdf
- Description:
- IC TRANSCEIVER INVERT 5.5V 20SO
- Quantity:
- Payment:
- Shipping:
Inventory:1,451
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Product details
Overview
74HCT640D,653 from Nexperia (formerly Philips Semiconductors) is an octal inverting bus transceiver with 3-state outputs, designed for bidirectional data flow control between two 8-bit buses. It features direction control (DIR), active-low output enable (OE), propagation delay of 11 ns (typ.) at VCC = 4.5 V, and operates across −40 °C to +85 °C. Used in legacy industrial backplane interfaces and memory-mapped I/O expansion.
For engineers reviewing the 74HCT640D,653 datasheet, 74HCT640D,653 pinout, 74HCT640D,653 application, or 74HCT640D,653 equivalent, key selection criteria include its inverting logic behavior, 3-state isolation timing (tPZH/tPHZ ≤ 45 ns), bus driver output capability, and compatibility with LSTTL input thresholds.
Technical Context
The 74HCT640D,653 implements dual-directional data transfer using a single DIR input to select A→B (inverting) or B→A (inverting) paths, with OE enabling/disabling all outputs simultaneously into high-impedance state. Its HCT logic family ensures TTL-compatible input thresholds (VIH = 2.0 V min, VIL = 0.8 V max) while delivering CMOS-level output drive.
It supports cascading via OE and DIR signal routing, and its functional table confirms that when OE = LOW, outputs reflect inverted inputs based on DIR state; when OE = HIGH, all outputs enter Z-state regardless of DIR or data inputs - critical for bus arbitration in multi-master systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - ensures stable operation with standard 5 V TTL/CMOS rails and margin against supply ripple |
| tPHL / tPLH (An↔Bn) | 11 ns (typ.) at VCC = 4.5 V, CL = 50 pF - enables reliable 30 MHz bus clocking in synchronous systems |
| tPZH / tPHZ (OE/DIR→output) | 18–45 ns (max) over temperature - defines minimum dead time required between direction changes and data sampling |
| Input Thresholds (HCT) | VIH = 2.0 V min, VIL = 0.8 V max - guarantees interoperability with 5 V TTL outputs without level shifting |
| Output Drive | Bus driver capability (±6 mA IOH/IOL @ VCC = 4.5 V) - sustains signal integrity across 10+ cm PCB traces loaded with multiple inputs |
| ICC Category | MSI (Medium Scale Integration) - indicates device complexity suitable for discrete bus interface layer, not system-on-chip integration |
Pinout & Package
74HCT640D,653 is housed in a 20-pin SO20 (Small Outline) package per JEDEC MS-013, with 0.65 mm lead pitch and body size 12.8 mm × 7.5 mm. Pin 10 is GND; Pin 20 is VCC; DIR (Pin 1) and OE (Pin 19) are active-low control inputs.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| DIR (Pin 1) | Direction control input | Selects data path: LOW = A→B (A0–A7 inverted to B0–B7), HIGH = B→A (B0–B7 inverted to A0–A7) |
| OE (Pin 19) | Active-low output enable | When HIGH, forces all A/B outputs into high-impedance Z-state - essential for bus sharing and hot-swap isolation |
| A0–A7 (Pins 2–9) | Bidirectional I/O port A | Inputs when DIR selects B→A; outputs (inverted) when DIR selects A→B - connects to local processor/data bus |
| B0–B7 (Pins 11–18) | Bidirectional I/O port B | Inputs when DIR selects A→B; outputs (inverted) when DIR selects B→A - connects to peripheral/memory bus |
| GND (Pin 10) | Ground reference | Common return for all internal logic and output drivers - must be low-inductance connection to minimize ground bounce |
| VCC (Pin 20) | Positive supply | Primary power rail for logic core and output buffers - requires local 100 nF ceramic decoupling adjacent to Pin 20 |
Key Features
| Feature | Design Value |
|---|---|
| Inverting transceiver logic | Guarantees signal polarity inversion on both A→B and B→A paths - simplifies design where complementary bus signaling is required |
| 3-state outputs with common OE | Enables clean bus contention avoidance in multi-drop architectures by simultaneously disabling all 16 I/O lines |
| TTL-compatible input thresholds | Accepts standard 5 V TTL logic levels without external biasing or level translators - reduces BOM count in mixed-logic systems |
| Propagation delay symmetry | Identical tPHL/tPLH spec for An→Bn and Bn→An paths - ensures deterministic timing in full-duplex or ping-pong bus protocols |
Applications
| Industrial Backplane Interface | Legacy Memory-Mapped I/O Expansion |
|---|---|
Use Scenario: Interfacing an 8-bit microcontroller bus to a parallel peripheral card in a DIN-rail mounted PLC chassis. IC Role / Device Role / Timing Role: Bidirectional inverting bus transceiver managing data flow between CPU address/data bus and isolated I/O module, with DIR synchronized to address decode and OE controlled by chip-select logic. Use Value: Enables galvanic isolation boundary crossing via optocouplers on A/B sides while preserving signal inversion needed for handshake protocol timing alignment. | Use Scenario: Adding parallel EEPROM or static RAM to an older 8051-based embedded controller with limited address space. IC Role / Device Role / Timing Role: Translates between non-inverting CPU data bus and inverting memory data bus, with OE tied to memory chip select and DIR fixed for read/write direction. Use Value: Eliminates need for discrete inverters and tristate buffers - reduces layout area and signal skew in space-constrained PCBs. |
| Multi-Master Bus Arbitration | Test Fixture Signal Routing |
Use Scenario: Arbitrating access between two microcontrollers sharing a common 8-bit diagnostic bus in automotive ECU test equipment. IC Role / Device Role / Timing Role: Isolates each MCU's data bus during idle periods using OE, and flips DIR to route diagnostics upstream/downstream under master control. Use Value: Prevents bus contention during handover; inverting behavior matches legacy protocol framing where ACK/NACK bits rely on polarity inversion. | Use Scenario: Reconfigurable signal path switching in automated board-level test fixtures for 8-bit logic families. IC Role / Device Role / Timing Role: Programmable bidirectional signal conditioner that routes, inverts, and isolates DUT signals under test controller command via DIR/OE. Use Value: Supports both stimulus injection and response capture on same pins - cuts fixture wiring complexity and improves repeatability vs. relay-based switching. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HCT245N | Non-inverting logic; identical pinout, AC/DC specs, and package | Requires external inverters if system-level inversion is mandatory; otherwise drop-in for non-inverting paths | Select when bus protocol does not require inversion - avoids redesign of downstream logic |
| 74HCT640PW,118 | TSSOP20 package (4.4 mm × 6.5 mm); identical electrical specs and function | Smaller footprint and finer pitch - suited for high-density boards but requires rework-capable assembly | Choose for space-constrained designs where SO20 thermal/mechanical robustness is not required |
Compared with SN74HCT245N and 74HCT640PW,118, the 74HCT640D,653 uniquely delivers inverting transceiver behavior in the industry-standard SO20 package - making it irreplaceable in legacy systems where signal polarity is hardwired into firmware or ASIC timing.
Availability
74HCT640D,653 is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy memory-mapped I/O expansion, multi-master bus arbitration, and test fixture signal routing requiring stable component supply and long-term obsolescence management.
Supply support for 74HCT640D,653 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-volume, high-reliability logic, discrete, and MOSFET solutions - spun off from Philips Semiconductors in 2017 with full IP and manufacturing continuity.
The 74HCT640D,653 belongs to Nexperia's legacy 74HCT logic family, engineered for drop-in replacement of obsolete TTL and early CMOS bus interfaces in industrial control, instrumentation, and telecom infrastructure.
FAQ
What is the logic polarity behavior of the 74HCT640D,653 during data transfer?
The 74HCT640D,653 performs inversion on all data paths: when DIR = LOW, A0–A7 inputs appear as inverted outputs on B0–B7; when DIR = HIGH, B0–B7 inputs appear as inverted outputs on A0–A7. This behavior is inherent to the silicon design and cannot be disabled - it is confirmed in the functional table and logic symbol of the official Nexperia datasheet.
Does the 74HCT640D,653 support operation at 3.3 V supply voltage?
No, the 74HCT640D,653 is specified only for VCC = 4.5 V to 5.5 V. Its HCT input thresholds and output drive characteristics are optimized for 5 V TTL compatibility. Operation below 4.5 V violates datasheet limits and may cause unreliable switching or increased propagation delay - use 74LVC640A or similar for 3.3 V systems.
How does the 74HCT640D,653 handle bus contention when OE is HIGH?
When OE is HIGH, all A0–A7 and B0–B7 outputs enter high-impedance (Z) state regardless of DIR or input values - effectively disconnecting both buses. This prevents current leakage or signal corruption during bus arbitration, and is validated in the functional table where OE = H results in Z outputs for all combinations of DIR and data.
Is the 74HCT640D,653 pin compatible with the 74HC640D,653?
Yes, the 74HCT640D,653 and 74HC640D,653 share identical pinout, package, and AC/DC timing structure. The sole difference is input threshold specification: HCT uses TTL-compatible VIH/VIL, while HC uses CMOS-ratio thresholds. Both are interchangeable in 5 V systems where input sources meet the stricter threshold requirement.
What is the maximum capacitive load the 74HCT640D,653 can drive on each output line?
The 74HCT640D,653 is characterized up to CL = 50 pF per output in AC specifications, with guaranteed timing performance. While it can physically drive higher capacitance, propagation delay increases linearly beyond this point - for loads >50 pF, derating curves in the "74HC/HCT Family Specifications" document must be applied to ensure setup/hold timing compliance.
74HCT640D,653 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- 74HCT
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Logic Type:
- Transceiver, Inverting
- Number of Elements:
- 1
- Number of Bits per Element:
- 8
- Input Type:
- -
- Output Type:
- 3-State
- Current - Output High, Low:
- 6mA, 6mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SO
74HCT640D,653 FAQ
1.How can I place an order for 74HCT640D,653 through Aetrix?
Please submit a Request for Quotation (RFQ) for 74HCT640D,653 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 74HCT640D,653 reliable?
The price and inventory of 74HCT640D,653 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74HCT640D,653 is usually 5 days.
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74HCT640D,653 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 74HCT640D,653 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 74HCT640D,653?
For technical support, including 74HCT640D,653 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74HCT640D,653 requirements.
6.How does Aetrix verify that 74HCT640D,653 is sourced from the original manufacturer or authorized distributors?
All 74HCT640D,653 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 74HCT640D,653 meets industry standards.
7.What is the process for return or replacement of 74HCT640D,653?
All 74HCT640D,653 units undergo pre-shipment inspection (PSI). If there is an issue with 74HCT640D,653, 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 74HCT640D,653 part is unused and in its original packaging.
Return procedure for 74HCT640D,653:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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