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Texas Instruments SN74HC640PWT
- Part No.:
- SN74HC640PWT
- Manufacturer:
- Texas Instruments
- Package:
- 20-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
SN74HC640PWT.pdf
- Description:
- IC TRANSCEIVER INVERT 6V 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,684
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Product details
Overview
SN74HC640PWT from Texas Instruments is an octal inverting bus transceiver with 3-state outputs, designed for bidirectional data flow control between two 8-bit buses. It operates across 2V–6V supply, delivers ±4 mA output drive at 5V, exhibits typical propagation delay of 8 ns (CL = 50 pF), and supports isolation via independent DIR and OE controls - used in industrial backplane interface and legacy system bus bridging.
For engineers reviewing the SN74HC640PWT datasheet, SN74HC640PWT pinout, SN74HC640PWT application, or SN74HC640PWT equivalent, key selection criteria include its inverting logic behavior, TSSOP-20 package footprint, 3-state timing parameters (ten/tdis), and compatibility with LSTTL-load-driven systems requiring voltage-level translation between 3.3V and 5V domains.
Technical Context
The SN74HC640PWT implements dual-directional 8-bit data routing controlled by a single DIR input: low DIR enables B→A transmission, high DIR enables A→B transmission. Its 3-state outputs are independently disabled by OE, allowing full bus isolation without contention.
All channels share identical electrical characteristics: input thresholds scale with VCC (VIH = 0.7×VCC, VIL = 0.3×VCC), output drive is symmetrical (±4 mA at 5V), and switching performance is specified at CL = 50 pF and CL = 150 pF to support both high-speed and capacitive-bus environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 2 V to 6 V - supports mixed-voltage system interfacing (e.g., 3.3V logic driving 5V bus) |
| Propagation Delay (tpd) | 8 ns typical at VCC = 5 V, CL = 50 pF - enables ≤125 MHz bus toggle rates in point-to-point configurations |
| Output Drive Strength | ±4 mA at VCC = 5 V - sufficient to directly drive 10 LSTTL loads without buffering |
| 3-State Enable/Disable Time | ten = 26 ns, tdis = 32 ns (VCC = 5 V, CL = 50 pF) - ensures clean bus release before next data phase |
| Input Leakage Current | ±1 µA max - minimizes static power and prevents floating-input-induced oscillation |
| Power Supply Current (ICC) | 80 µA max - enables low-quiescent-power operation in battery-backed or standby modes |
| Logic Function | Inverting transceiver - A/B bus data inverted on transfer; critical for polarity-matched legacy bus protocols |
Pinout & Package
TSSOP-20 package (PW), 4.4 mm × 6.5 mm body, 0.65 mm lead pitch, 1.2 mm max height - optimized for high-density PCB layouts with thermal pad omitted.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (OE) | Output Enable | Active-low global control: drives all Y outputs into high-impedance when high |
| 2–9 (A1–A8) | Input/Output Port A | Data terminals for first 8-bit bus; direction determined by DIR state |
| 10 (GND) | Ground Reference | Primary return path for all I/O and supply currents; must be low-impedance |
| 11–18 (B1–B8) | Input/Output Port B | Data terminals for second 8-bit bus; complementary to A-side in transceiver mode |
| 19 (DIR) | Direction Control | High = A→B transfer; Low = B→A transfer; determines signal flow polarity |
| 20 (VCC) | Positive Supply | Single rail powering internal logic and output drivers; bypass capacitor required |
Key Features
| Feature | Design Value |
|---|---|
| Wide supply range (2–6 V) | Enables interoperability across 3.3V microcontrollers and 5V peripheral buses without level shifters |
| High-current 3-state outputs | Drives 10 LSTTL loads directly - eliminates need for external bus buffers in legacy designs |
| Low ICC (80 µA max) | Reduces system standby current in power-sensitive applications such as portable test equipment |
| Specified timing at CL = 150 pF | Validates reliable operation on long traces or heavily loaded backplanes common in industrial PLCs |
| Inverting logic architecture | Maintains signal integrity in systems where bus inversion is protocol-mandated (e.g., certain ISA derivatives) |
Applications
| Industrial Backplane Interface | Legacy System Bus Bridging |
|---|---|
Use Scenario: Isolating and translating data between CPU and I/O expansion slots in programmable logic controllers. IC Role / Device Role / Timing Role: Bidirectional bus transceiver managing 8-bit parallel data flow under DIR-controlled direction and OE-gated enable timing. Use Value: Prevents bus contention during slot hot-swap and supports mixed-voltage (3.3V/5V) module interoperability. | Use Scenario: Connecting modern microcontroller peripherals to aging ISA-compatible peripheral cards. IC Role / Device Role / Timing Role: Inverting transceiver synchronizing data transfers between asynchronous bus domains using OE-strobed handshaking. Use Value: Eliminates need for discrete inverters and level shifters while meeting strict tpd and tdis requirements of ISA timing budgets. |
| Test Equipment Data Path | Embedded Diagnostic Subsystem |
Use Scenario: Routing sensor data from multiple ADC channels to a central FPGA-based acquisition engine. IC Role / Device Role / Timing Role: 3-state-enabled multiplexer substitute enabling time-division sharing of a single 8-bit data lane. Use Value: Reduces PCB layer count by replacing discrete switches; low ICC extends battery life in portable calibrators. | Use Scenario: Providing isolated communication between safety-critical MCU and non-certified diagnostic firmware modules. IC Role / Device Role / Timing Role: Directionally gated data conduit ensuring no unintended writes occur during firmware update sequences. Use Value: Hardware-enforced bus isolation meets IEC 61508 functional safety requirement for fault containment. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HCT640PWR | TTL-compatible input thresholds (VIH = 2 V min), same pinout and function | Better noise immunity in noisy industrial environments with TTL-level noise margins | Select when interfacing with legacy 5V TTL logic families where HC thresholds may cause marginal switching |
| 74LCX640MTCX | Lower VCC range (2.0–3.6 V), higher speed (tpd = 5.5 ns), different pinout (20-pin TSSOP but shifted pin mapping) | Optimized for 3.3V-only systems; not drop-in compatible due to pin reordering and missing 5V tolerance | Choose only for new 3.3V designs prioritizing speed and lower power; requires PCB redesign |
Compared with SN74HCT640PWR, the SN74HC640PWT offers wider voltage flexibility but reduced noise margin; versus 74LCX640MTCX, it provides 5V tolerance and pin compatibility at the cost of higher propagation delay and static current.
Availability
SN74HC640PWT is available at Aetrix Electronics and suitable for industrial backplane interface, legacy system bus bridging, and embedded diagnostic subsystems requiring stable component supply across extended product lifecycles.
Supply support for SN74HC640PWT 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 U.S.-based semiconductor company specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.
The SN74HC640PWT belongs to TI's 74HC logic family, engineered for robust, low-power, wide-supply-voltage digital interfacing in space-constrained industrial control and instrumentation systems.
FAQ
What is the maximum operating temperature for SN74HC640PWT?
The SN74HC640PWT has a specified operating free-air temperature range of –40°C to +85°C, consistent with commercial-grade TSSOP packaging. This rating is validated per TI's Recommended Operating Conditions table and applies to continuous operation under rated supply and load conditions. Derating is required above 70°C ambient if power dissipation exceeds 100 mW.
Does SN74HC640PWT support 3.3V-only operation?
Yes, SN74HC640PWT fully supports 3.3V operation: VIH = 2.31 V min and VIL = 0.99 V max at VCC = 3.3 V, and output drive remains compliant (VOH ≥ 3.15 V, VOL ≤ 0.1 V). Its 2V–6V supply range makes it suitable for 3.3V systems without level translation, provided input signals meet HC threshold requirements.
Is SN74HC640PWT pin-compatible with SN74HC245?
No, SN74HC640PWT is not pin-compatible with SN74HC245. While both are octal 3-state transceivers, SN74HC640PWT uses inverting logic and assigns DIR to pin 19 and OE to pin 1, whereas SN74HC245 places OE on pin 1 and DIR on pin 19 but implements non-inverting logic. Pin mapping differs for A/B ports, and functional behavior diverges - direct substitution would cause logic inversion errors.
What decoupling capacitance is recommended for SN74HC640PWT?
Texas Instruments recommends a 0.1 µF ceramic capacitor placed as close as possible to the VCC (pin 20) and GND (pin 10) pins of SN74HC640PWT. For systems with high-frequency noise or multiple transceivers, paralleling with a 1 µF capacitor improves low-frequency bypassing. Layout guidelines specify ≤5 mm trace length between capacitor pads and IC pins to maintain effective high-frequency suppression.
Can SN74HC640PWT drive a 150 pF bus load reliably?
Yes, SN74HC640PWT switching characteristics are explicitly characterized at CL = 150 pF: tpd = 41 ns max, ten = 68 ns max, and tdis = 49 ns max at VCC = 6 V. These values confirm reliable timing margin for heavily loaded buses found in industrial backplanes or multi-drop configurations, provided trace impedance and termination align with HC-family design practices.
SN74HC640PWT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HC
- Package/Case:
- 20-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- Logic Type:
- Transceiver, Inverting
- Number of Elements:
- 1
- Number of Bits per Element:
- 8
- Input Type:
- -
- Output Type:
- 3-State
- Current - Output High, Low:
- 7.8mA, 7.8mA
- Voltage - Supply:
- 2V ~ 6V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-TSSOP
SN74HC640PWT FAQ
1.How can I place an order for SN74HC640PWT through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HC640PWT 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 SN74HC640PWT reliable?
The price and inventory of SN74HC640PWT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HC640PWT is usually 5 days.
3.What payment methods are accepted for SN74HC640PWT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74HC640PWT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74HC640PWT?
SN74HC640PWT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HC640PWT 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 SN74HC640PWT?
For technical support, including SN74HC640PWT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HC640PWT requirements.
6.How does Aetrix verify that SN74HC640PWT is sourced from the original manufacturer or authorized distributors?
All SN74HC640PWT 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 SN74HC640PWT meets industry standards.
7.What is the process for return or replacement of SN74HC640PWT?
All SN74HC640PWT units undergo pre-shipment inspection (PSI). If there is an issue with SN74HC640PWT, 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 SN74HC640PWT part is unused and in its original packaging.
Return procedure for SN74HC640PWT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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