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Texas Instruments CD54HCT640F3A
- Part No.:
- CD54HCT640F3A
- Manufacturer:
- Texas Instruments
- Package:
- 20-CDIP (0.300", 7.62mm)
- Datasheet:
-
CD54HCT640F3A.pdf
- Description:
- HIGH SPEED CMOS LOGIC OCTAL INVE
- Quantity:
- Payment:
- Shipping:
Inventory:4,537
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Product details
Overview
CD54HCT640F3A from Texas Instruments is a high-speed CMOS octal three-state inverting bus transceiver in a 20-pin CDIP package, operating at 4.5–5.5 V with propagation delay of 22–33 ns (A↔B), ±6 mA output drive, and -55°C to +125°C temperature range-used for bidirectional data bus isolation in military-grade avionics and ruggedized industrial backplanes.
For engineers reviewing the CD54HCT640F3A datasheet, CD54HCT640F3A pinout, CD54HCT640F3A application, or CD54HCT640F3A equivalent, key selection criteria include LSTTL-compatible input thresholds (VIL ≤ 0.8 V, VIH ≥ 2.0 V), three-state control via DIR/OE logic, high-impedance leakage < ±5 µA, and compatibility with 15-LSTTL-load bus capacitance.
Technical Context
The CD54HCT640F3A implements dual-directional inverting data flow between two 8-bit buses using separate DIR (direction) and OE (output enable) control inputs. Its TTL-compatible inputs accept standard LSTTL voltage levels while delivering CMOS-level outputs with rail-to-rail swing and balanced rise/fall times.
It operates exclusively in the military temperature range (-55°C to +125°C) and supports only 4.5–5.5 V supply; no low-voltage (2–4.4 V) or extended-range operation is specified. All eight A-side and B-side I/Os are fully buffered and support simultaneous high-Z state entry/exit with matched propagation delays.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - ensures direct drop-in replacement for legacy LSTTL bus systems without level-shifting. |
| Propagation Delay (A↔B) | 22 ns (typ), 33 ns (max) at VCC = 4.5 V, CL = 50 pF - enables reliable 20+ MHz bus clocking in synchronous backplane designs. |
| Output Drive | ±6 mA (TTL load) - sufficient to drive 15 LSTTL inputs while maintaining VOL ≤ 0.4 V and VOH ≥ 3.7 V. |
| Input Thresholds | VIL = 0.8 V (max), VIH = 2.0 V (min) - guarantees robust noise margin against LSTTL output transitions. |
| Operating Temperature | -55°C to +125°C - qualified per MIL-PRF-38535 for use in aerospace, defense, and downhole instrumentation. |
| Three-State Leakage | ±5 µA (max) at -55°C to +125°C - minimizes standby current in powered-down bus segments. |
| Quiescent Current | 160 µA (max) at -55°C to +125°C - supports low-power system sleep modes without compromising bus integrity. |
Pinout & Package
CD54HCT640F3A uses a 20-pin Ceramic Dual In-line Package (CDIP, J-body) with 26.92 mm × 6.92 mm footprint and through-hole mounting. Pin 1 is marked by a beveled corner or notch on the package top edge.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8 | A-side data inputs/outputs | Inverting bidirectional I/O ports; driven low when A-input is high, high when A-input is low - requires external pull-ups if used as open-drain-like interface. |
| 11, 12, 13, 14, 15, 16, 17, 18 | B-side data inputs/outputs | Inverting bidirectional I/O ports mirroring A-side behavior; direction determined by DIR pin state. |
| 9 | DIR (Direction Control) | Active-high signal: DIR = L enables A→B flow; DIR = H enables B→A flow - determines inversion path polarity. |
| 10 | OE (Output Enable) | Active-low signal: OE = L enables transceiver outputs; OE = H forces all A/B pins into high-impedance state - critical for bus arbitration. |
| 20 | VCC | Positive supply terminal - must be bypassed with 0.1 µF ceramic capacitor placed within 5 mm of pin. |
| 10 | GND | Ground reference - shared return path for all I/O and supply currents; requires low-inductance connection to system ground plane. |
Key Features
| Feature | Design Value |
|---|---|
| Inverting bidirectional data path | Ensures signal polarity reversal across buses - required in legacy MIL-STD-1553 or ARINC-429 repeater stages where phase inversion is part of protocol framing. |
| LSTTL input compatibility | Accepts standard TTL logic levels without external biasing - eliminates need for resistor networks or level translators in mixed-technology backplanes. |
| Three-state control with independent DIR/OE | Enables precise bus arbitration: DIR selects direction while OE independently disables all outputs - prevents bus contention during mode switching. |
| Military-grade temperature range | Validated operation from -55°C to +125°C - meets screening requirements for Class B (space) and Class S (military) applications per MIL-PRF-38535. |
| Low dynamic power dissipation | Cpd = 41 pF - reduces switching current in high-frequency bus environments, lowering thermal load in sealed chassis. |
Applications
| Avionics Data Bus Isolation | Industrial PLC Backplane Interface |
|---|---|
Use Scenario: Isolating redundant MIL-STD-1553B remote terminal buses in flight control computers to prevent fault propagation between channels. IC Role / Device Role / Timing Role: Inverting transceiver managing bidirectional command/data flow between primary and backup bus controllers with synchronized DIR/OE timing. Use Value: Enables hot-swap capability and fault containment via high-impedance state while maintaining strict 33 ns max propagation delay for real-time deterministic response. | Use Scenario: Interfacing legacy 5 V TTL-based I/O modules with modern 3.3 V controller cards in modular PLC racks. IC Role / Device Role / Timing Role: Level-shifting and bus-driving transceiver translating signals between mismatched voltage domains without external resistors. Use Value: Eliminates need for discrete level shifters; ±6 mA drive sustains signal integrity across 30 cm ribbon-cable backplanes with up to 15 LSTTL loads. |
| Ruggedized Test Equipment Interface | Defense Radar Signal Conditioning |
Use Scenario: Buffering and isolating digital test patterns between ATE mainframe and DUT board under thermal shock (-55°C to +125°C cycling). IC Role / Device Role / Timing Role: Three-state bus transceiver enabling safe pattern injection and response capture without bus contention during vector loading. Use Value: Guaranteed functionality across full military temperature range avoids calibration drift or timing failure during environmental stress testing. | Use Scenario: Routing time-critical radar pulse timing signals between analog front-end and digital processing units in airborne radar pods. IC Role / Device Role / Timing Role: Inverting buffer stage ensuring consistent edge alignment and minimized skew between parallel timing lines. Use Value: Balanced propagation delay (22–33 ns) and transition time (12–15 ns) preserve sub-ns timing margins required for pulse-Doppler coherence. |
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 |
|---|---|---|---|
| CD74HCT640E | PDIP-20 package, commercial temperature range (-55°C to +125°C not guaranteed; rated -40°C to +85°C), RoHS-compliant NiPdAu finish. | Suitable for non-military industrial control but lacks QML qualification and extended cold-start performance. | Select when cost, RoHS compliance, or volume procurement outweighs military temp range requirement. |
| SN74HCT640N | Same PDIP-20 footprint, identical electrical specs, but TI's commercial-grade version with -40°C to +85°C rating and no MIL-PRF-38535 traceability. | Valid for automotive body electronics or telecom infrastructure where extended temperature is not mandated. | Choose for high-volume commercial designs requiring TI's standard logistics and shorter lead times. |
Compared with CD74HCT640E and SN74HCT640N, CD54HCT640F3A uniquely delivers guaranteed -55°C startup, QML Class B certification, and SNPB lead finish - making it the sole option for spaceflight, missile guidance, and nuclear instrumentation where radiation tolerance and extreme thermal resilience are mandatory.
Availability
CD54HCT640F3A is available at Aetrix Electronics and suitable for avionics data bus isolation, industrial PLC backplane interface, ruggedized test equipment interface, and defense radar signal conditioning requiring stable component supply across extended temperature and long lifecycle commitments.
Supply support for CD54HCT640F3A 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
Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and logic solutions with over 90 years of innovation in high-reliability components.
The CD54HCT640F3A belongs to TI's military-grade HCT logic family, designed specifically for ruggedized digital systems requiring LSTTL compatibility, wide temperature operation, and QML certification in aerospace and defense platforms.
FAQ
What is the maximum propagation delay of CD54HCT640F3A under worst-case military temperature conditions?
The maximum propagation delay of CD54HCT640F3A is 33 ns (A↔B direction) at VCC = 4.5 V, CL = 50 pF, and over the full -55°C to +125°C operating range. This value is measured per TI's SCHS192C datasheet Section 5.5 and applies to both forward and reverse data paths when DIR is asserted.
Does CD54HCT640F3A support 3.3 V logic interfaces?
No, CD54HCT640F3A does not support 3.3 V logic interfaces. It is strictly specified for 4.5–5.5 V operation and requires LSTTL-compatible input thresholds (VIH ≥ 2.0 V, VIL ≤ 0.8 V). Direct connection to 3.3 V systems risks undervoltage lockout or undefined switching behavior; level translation is required.
How is the direction of data flow controlled in CD54HCT640F3A?
Data flow direction in CD54HCT640F3A is controlled by the DIR pin: when DIR = Low, data flows from A-side to B-side; when DIR = High, data flows from B-side to A-side. This control is independent of OE, allowing direction change while outputs remain in high-impedance state to avoid bus contention.
What packaging and marking details confirm authenticity of CD54HCT640F3A?
Authentic CD54HCT640F3A devices use a 20-pin Ceramic Dual In-line Package (CDIP-J) with SNPB (tin-lead) finish, marked "5962-8974001RA" or "CD54HCT640F3A" on the top surface. The package measures 26.92 mm × 6.92 mm and is supplied in tubes of 20 units per TI's orderable addendum.
Is CD54HCT640F3A pin-compatible with CD54HC640F3A?
Yes, CD54HCT640F3A is pin-compatible with CD54HC640F3A - both share identical 20-pin CDIP-J package, pinout, and functional block diagram. However, CD54HC640F3A operates at 2–6 V and lacks LSTTL input compatibility, so substitution requires verification of supply voltage and input source logic family.
CD54HCT640F3A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 54HCT
- Package/Case:
- 20-CDIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Active
- 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:
- -55°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 20-CDIP
CD54HCT640F3A FAQ
1.How can I place an order for CD54HCT640F3A through Aetrix?
Please submit a Request for Quotation (RFQ) for CD54HCT640F3A 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 CD54HCT640F3A reliable?
The price and inventory of CD54HCT640F3A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CD54HCT640F3A is usually 5 days.
3.What payment methods are accepted for CD54HCT640F3A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CD54HCT640F3A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CD54HCT640F3A?
CD54HCT640F3A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CD54HCT640F3A 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 CD54HCT640F3A?
For technical support, including CD54HCT640F3A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CD54HCT640F3A requirements.
6.How does Aetrix verify that CD54HCT640F3A is sourced from the original manufacturer or authorized distributors?
All CD54HCT640F3A 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 CD54HCT640F3A meets industry standards.
7.What is the process for return or replacement of CD54HCT640F3A?
All CD54HCT640F3A units undergo pre-shipment inspection (PSI). If there is an issue with CD54HCT640F3A, 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 CD54HCT640F3A part is unused and in its original packaging.
Return procedure for CD54HCT640F3A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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