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NXP Semiconductors 74HCT640DB,112
- Part No.:
- 74HCT640DB,112
- Manufacturer:
- NXP Semiconductors
- Package:
- 20-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
74HCT640DB,112.pdf
- Description:
- IC TXRX INVERT 5.5V 20SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,489
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Product details
Overview
74HCT640DB,112 from NXP Semiconductors is a high-speed CMOS octal bus transceiver with inverting 3-state outputs, designed for bidirectional data flow 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 bus-driver output capability for TTL-compatible loads.
For engineers reviewing the 74HCT640DB,112 datasheet, 74HCT640DB,112 pinout, 74HCT640DB,112 application, or 74HCT640DB,112 equivalent, key selection criteria include 3-state timing (tPZH/tPHZ ≤ 45 ns), inverting logic behavior, 4.5–5.5 V supply operation, and SO20 package compatibility with legacy 74-series logic systems.
Technical Context
The 74HCT640DB,112 implements dual-directional bus interface logic using Si-gate CMOS technology, fully compliant with JEDEC Standard No. 7A and pin-compatible with LSTTL. Its DIR input selects data flow direction (A→B or B→A), while OE independently places all outputs in high-impedance state regardless of DIR state.
Each transceiver channel inverts data: when enabled and A→B mode, A0–A7 inputs appear as inverted complements on B0–B7 outputs. The device operates across −40 °C to +85 °C with guaranteed AC performance at VCC = 4.5 V and CL = 50 pF, supporting synchronous bus arbitration in industrial control backplanes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Propagation Delay (An↔Bn) | 11 ns typical at VCC = 4.5 V, CL = 50 pF - enables sub-10 MHz synchronous bus cycles |
| 3-State Enable Time (tPZH) | 18 ns typical - supports fast bus turnaround in multiplexed address/data systems |
| Supply Voltage Range | 4.5 V to 5.5 V - ensures robust TTL-level compatibility without level-shifting |
| Input Voltage Threshold (HCT) | VIL = 0.8 V, VIH = 2.0 V - matches standard TTL logic levels for direct interfacing |
| Output Drive Capability | ±6 mA at VCC = 4.5 V - drives 10 LSTTL loads per output, suitable for shared bus termination |
| Power Dissipation Capacitance | 35 pF - used to calculate dynamic power: PD = 35 × VCC² × fi + Σ(CL × VCC² × fo) |
| Operating Temperature | −40 °C to +85 °C - qualified for industrial ambient environments |
Pinout & Package
74HCT640DB,112 is housed in a 20-pin small-outline (SO) package (SO20), 7.5 mm wide, with 1.27 mm pitch and surface-mount gull-wing leads. Pin 1 is marked by a bevelled corner or notch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | DIR | Direction control input: LOW = A→B, HIGH = B→A; determines data flow path |
| 2–9 | A0–A7 | Bidirectional I/O port A: inputs when DIR=HIGH & OE=LOW; outputs when DIR=LOW & OE=LOW |
| 10 | GND | Ground reference for all internal circuitry and signal return path |
| 11–18 | B0–B7 | Bidirectional I/O port B: outputs when DIR=LOW & OE=LOW; inputs when DIR=HIGH & OE=LOW |
| 19 | OE | Active-low output enable: HIGH forces all A/B pins into high-impedance state |
| 20 | VCC | Positive supply voltage (4.5–5.5 V); powers internal logic and output drivers |
Key Features
| Feature | Design Value |
|---|---|
| Inverting transceiver logic | Each data path inverts signal polarity - simplifies complement-based bus arbitration protocols |
| Independent 3-state control | OE disables all outputs regardless of DIR state - enables clean bus isolation during arbitration |
| TTL-compatible input thresholds | VIL = 0.8 V / VIH = 2.0 V - eliminates need for external level shifters when interfacing with legacy TTL |
| Bus-driver output strength | ±6 mA drive at VCC = 4.5 V - sustains signal integrity across 10-cm PCB traces with 50 pF load |
| JEDEC 7A compliance | Fully conforms to industry-standard timing, voltage, and interface definitions - ensures interoperability with other 74-series logic |
Applications
| Industrial PLC Backplane | Legacy Microprocessor Bus Interface |
|---|---|
Use Scenario: Bidirectional data exchange between CPU and I/O expansion modules over a shared 8-bit bus with arbitration logic. IC Role / Device Role / Timing Role: Octal transceiver providing isolated, direction-controlled, inverting data path between processor and peripheral cards. Use Value: Enables deterministic bus turnaround via DIR/OE coordination; 11 ns propagation supports 8 MHz bus clocking with margin. | Use Scenario: Interfacing Z80 or 8085 microprocessors with memory-mapped peripherals requiring inverted data handshake. IC Role / Device Role / Timing Role: Inverting bus transceiver translating between CPU data bus and peripheral register interfaces. Use Value: Direct TTL-level compatibility avoids level-shifter components; 3-state isolation prevents bus contention during DMA cycles. |
| Test Equipment Data Acquisition | Automated Meter Reading Hub |
Use Scenario: Multiplexing sensor data streams from multiple analog front-ends onto a central controller bus under software direction. IC Role / Device Role / Timing Role: Direction-configurable buffer isolating sensor-side and controller-side bus segments during sampling intervals. Use Value: DIR-controlled flow direction and OE-driven high-Z state eliminate hardware switches; 45 ns max tPZH allows <10 µs reconfiguration. | Use Scenario: Aggregating pulse-count data from mechanical utility meters via opto-isolated inputs into a low-power MCU bus. IC Role / Device Role / Timing Role: Low-quiescent-current transceiver enabling intermittent bus activation to minimize system standby power. Use Value: HCT logic family ensures stable operation at 5 V with minimal ICC increase; SO20 package fits compact meter PCB layouts. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 74HCT245D,653 | Non-inverting outputs; identical pinout, timing, and supply specs | Requires logic inversion upstream/downstream if system relies on inverting behavior | Select when bus protocol mandates non-inverted data path or when redesign permits external inverters |
| SN74HCT640N | DIP-20 package; same electrical specs but through-hole mounting and higher thermal resistance | Suitable only for prototyping or legacy through-hole assembly; not for high-density SMT production | Choose for breadboard validation or repair of legacy DIP-based systems where SO20 footprint is incompatible |
Compared with 74HCT640DB,112, the 74HCT245D,653 offers identical timing and drive but requires external inversion logic, while SN74HCT640N provides identical functionality in through-hole form - neither is pin-compatible replacement due to functional (inversion) or mechanical (package) differences.
Availability
74HCT640DB,112 is available at Aetrix Electronics and suitable for industrial PLC backplanes, legacy microprocessor bus interfaces, and automated meter reading hubs requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for 74HCT640DB,112 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
NXP Semiconductors is a global semiconductor leader delivering high-performance mixed-signal and logic solutions for automotive, industrial, and IoT applications, with core expertise in energy-efficient digital logic families.
The 74HCT640DB,112 belongs to NXP's legacy 74HCT logic portfolio, engineered specifically for robust TTL-compatible interfacing in industrial control and instrumentation systems where reliability and long-term availability are critical.
FAQ
What is the function of the DIR pin on the 74HCT640DB,112?
The DIR (direction control) pin on the 74HCT640DB,112 determines data flow direction: when DIR is LOW, data passes from A0–A7 to B0–B7; when DIR is HIGH, data flows from B0–B7 to A0–A7. This bidirectional control enables flexible bus arbitration without external routing logic, and the 74HCT640DB,112 maintains full 3-state capability regardless of DIR state when OE is HIGH.
Does the 74HCT640DB,112 support 3.3 V operation?
No, the 74HCT640DB,112 is specified only for 4.5 V to 5.5 V operation and is not guaranteed to function correctly at 3.3 V. Its TTL-compatible input thresholds (VIL = 0.8 V, VIH = 2.0 V) and output drive characteristics are optimized for 5 V systems. For 3.3 V applications, consider the 74LVC640A or similar LVCMOS-family transceivers instead of the 74HCT640DB,112.
How does the inverting behavior of the 74HCT640DB,112 affect system design?
The 74HCT640DB,112 inverts data on both A→B and B→A paths: an input HIGH on A0 produces a LOW on B0 when enabled. This must be accounted for in protocol layer logic or compensated with external inverters. Unlike non-inverting alternatives such as the 74HCT245, the 74HCT640DB,112 reduces component count in systems requiring complemented bus signals, such as certain parity or checksum architectures.
What is the maximum capacitive load the 74HCT640DB,112 can drive reliably?
The 74HCT640DB,112 is characterized for CL = 50 pF in AC specifications, with propagation delay and transition time validated under that condition. While it can drive higher capacitance, timing margins degrade: at CL = 100 pF, tPHL/tPLH increases to ~18 ns (typ.), and output rise/fall times exceed 15 ns. For reliable operation beyond 50 pF, verify timing closure in the target 74HCT640DB,112 application using worst-case VCC and temperature conditions.
Is the 74HCT640DB,112 pin-compatible with the 74HC640DB,112?
Yes, the 74HCT640DB,112 is pin-compatible and functionally identical to the 74HC640DB,112 in layout and connection, differing only in input threshold voltages and AC timing under varying VCC. The 74HCT640DB,112 uses TTL-compatible inputs (VIH = 2.0 V), while the 74HC640DB,112 requires CMOS thresholds (VIH ≈ 3.5 V at VCC = 5 V). Both share identical pinout, DIR/OE logic, and SO20 package dimensions.
74HCT640DB,112 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- 74HCT
- Package/Case:
- 20-SSOP (0.209", 5.30mm Width)
- Packaging:
- Tube
- 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-SSOP
74HCT640DB,112 FAQ
1.How can I place an order for 74HCT640DB,112 through Aetrix?
Please submit a Request for Quotation (RFQ) for 74HCT640DB,112 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 74HCT640DB,112 reliable?
The price and inventory of 74HCT640DB,112 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74HCT640DB,112 is usually 5 days.
3.What payment methods are accepted for 74HCT640DB,112?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74HCT640DB,112 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 74HCT640DB,112?
74HCT640DB,112 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 74HCT640DB,112 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 74HCT640DB,112?
For technical support, including 74HCT640DB,112 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74HCT640DB,112 requirements.
6.How does Aetrix verify that 74HCT640DB,112 is sourced from the original manufacturer or authorized distributors?
All 74HCT640DB,112 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 74HCT640DB,112 meets industry standards.
7.What is the process for return or replacement of 74HCT640DB,112?
All 74HCT640DB,112 units undergo pre-shipment inspection (PSI). If there is an issue with 74HCT640DB,112, 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 74HCT640DB,112 part is unused and in its original packaging.
Return procedure for 74HCT640DB,112:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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