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Texas Instruments SN74HC640PW
- Part No.:
- SN74HC640PW
- Manufacturer:
- Texas Instruments
- Package:
- 20-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
SN74HC640PW.pdf
- Description:
- IC TRANSCEIVER INVERT 6V 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:455
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Product details
Overview
SN74HC640PW from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for bidirectional data flow between two 8-bit buses. It features inverting logic, operates from 2V to 6V, delivers ±4-mA output drive at 5V, and achieves typical propagation delay of 8ns (CL = 50 pF, VCC = 6V). It is used in microcontroller peripheral interfacing where bus isolation and direction control are required.
For engineers reviewing the SN74HC640PW datasheet, SN74HC640PW pinout, SN74HC640PW application, or SN74HC640PW equivalent, key selection considerations include its TSSOP-20 package, 3-state enable/disable timing (ten/tdis), inverting signal path, and compatibility with LSTTL loads in industrial control backplanes and legacy system upgrades.
Technical Context
The SN74HC640PW implements asynchronous bidirectional data transfer via a single DIR pin that selects A→B or B→A direction, and an OE pin that places all eight outputs in high-impedance state. Its inverting logic means input-to-output polarity is inverted across all channels.
It supports wide supply voltage (2–6V), exhibits low ICC (≤80 µA), and maintains stable switching performance across –40°C to +85°C. Input clamp current is ±20 mA, and absolute maximum VCC is 7 V - enabling robust operation in mixed-voltage systems with transient margin.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 2 V to 6 V - supports direct interface with 3.3V and 5V logic domains without level shifters. |
| Propagation Delay (tpd) | 8 ns typical at VCC = 6 V, CL = 50 pF - enables reliable operation in 100+ MHz bus clock domains with margin. |
| Output Drive | ±4 mA at VCC = 5 V - sufficient to drive 10 LSTTL loads, ensuring noise-immune fanout in noisy industrial environments. |
| 3-State Enable Time (ten) | 22 ns max at VCC = 6 V - defines minimum time from OE assertion to valid output, critical for synchronous bus arbitration. |
| Input Current (II) | ±1 µA max - minimizes loading on upstream drivers and reduces power in high-density bus configurations. |
| Power Supply Current (ICC) | 80 µA max - enables low-static-power operation in battery-backed or energy-sensitive subsystems. |
| Logic Polarity | Inverting - output complements input; must be accounted for in protocol layer or upstream logic design. |
Pinout & Package
TSSOP-20 package (PW), 4.40 mm × 6.50 mm body size, 1.2 mm max height, 0.65 mm lead pitch, JEDEC MO-153 compliant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8 (A1–A8) | Input/Output (A-side bus) | Octal bidirectional data terminals connected to first bus; internally inverted relative to B-side. |
| 11, 13, 14, 15, 16, 17, 18, 19 (B1–B8) | Input/Output (B-side bus) | Octal bidirectional data terminals connected to second bus; inverted relative to A-side. |
| 9 (DIR) | Direction Control Input | Low = B→A transfer; High = A→B transfer - determines real-time data flow direction. |
| 10 (OE) | Output Enable Input | Low = outputs active; High = all outputs in high-impedance - enables bus isolation during contention or standby. |
| 20 (VCC) | Positive Supply | Primary power rail; bypass capacitor (0.1 µF) required adjacent to pin for noise suppression. |
| 12 (GND) | Ground Reference | Signal and power return; must be low-impedance connection to minimize ground bounce in multi-channel switching. |
Key Features
| Feature | Design Value |
|---|---|
| Wide-Voltage Operation | 2–6 V supply range allows seamless integration into mixed-voltage systems (e.g., 3.3V MCU + 5V legacy peripherals). |
| High-Current 3-State Outputs | ±4 mA drive at 5 V ensures clean signal integrity when driving long traces or multiple LSTTL inputs in industrial backplanes. |
| Low Static Power | 80 µA max ICC enables use in always-on monitoring circuits without compromising system-level power budgets. |
| Fast Switching | 8 ns typical tpd at 6 V supports high-speed burst transfers in data acquisition and test equipment interfaces. |
| Inverting Signal Path | Guaranteed inversion simplifies logic design in applications requiring complemented handshake or parity signals. |
Applications
| Microcontroller Bus Expansion | Industrial Backplane Interface |
|---|---|
Use Scenario: Expanding GPIO or address/data bus of an ARM Cortex-M4 MCU to connect external SRAM and I/O expanders. IC Role / Device Role / Timing Role: Bidirectional bus transceiver isolating MCU core from peripheral bus loading while enabling direction-controlled data mirroring. Use Value: Eliminates need for discrete logic or dual-direction buffers; 8ns tpd preserves timing margins in 20-MHz parallel memory access cycles. | Use Scenario: Interfacing PLC CPU module with distributed I/O racks over a shared 8-bit parallel backplane. IC Role / Device Role / Timing Role: Directionally controlled data repeater with 3-state isolation during rack hot-swap or fault recovery. Use Value: ±4 mA drive sustains signal integrity across 30 cm backplane traces; OE-controlled isolation prevents bus contention during module insertion/removal. |
| Legacy System Upgrade Bridge | Test Equipment Signal Routing |
Use Scenario: Adapting vintage 8-bit microprocessor (Z80/8085) bus to modern FPGA-based controller with different voltage and timing requirements. IC Role / Device Role / Timing Role: Level-tolerant bidirectional translator providing direction and enable control between mismatched subsystems. Use Value: 2–6 V operation bridges 5V legacy logic and 3.3V FPGA I/O; inverting logic accommodates existing control signal polarity without redesign. | Use Scenario: Dynamic reconfiguration of signal paths in automated test equipment (ATE) for DUT stimulus/response routing. IC Role / Device Role / Timing Role: Programmable bus switch enabling FPGA-controlled selection of analog/digital signal sources to measurement front-end. Use Value: 22 ns enable time allows sub-50 ns path reconfiguration; TSSOP-20 footprint supports high-density PCB layout in compact ATE modules. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HCT640PW | TTL-compatible input thresholds (VIH = 2.0 V min at VCC = 4.5 V); identical pinout and function. | Better suited for mixed 5V TTL/CMOS systems where input noise immunity is critical. | Choose SN74HCT640PW when interfacing with legacy TTL outputs or noisy industrial sensors. |
| SN74LV640APW | Lower voltage range (1.65–5.5 V); higher speed (tpd = 5.5 ns typ at 3.3 V); same TSSOP-20 package. | Optimized for 3.3V-only systems with tighter timing budgets, such as portable instrumentation. | Choose SN74LV640APW for new 3.3V designs requiring faster throughput and lower power than HC-family devices. |
Compared with SN74HC640PW, SN74HCT640PW offers improved noise margin with TTL input compatibility but same 5V operation, while SN74LV640APW delivers superior speed and 3.3V efficiency at the cost of reduced 5V tolerance - making each optimal for distinct voltage and timing constraints.
Availability
SN74HC640PW is available at Aetrix Electronics and suitable for industrial control backplanes, microcontroller bus expansion, and legacy system upgrade projects requiring stable component supply and long-term sourcing continuity.
Supply support for SN74HC640PW 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 for industrial, automotive, and communications markets.
The SNx4HC640 product line delivers robust, wide-supply-voltage octal transceivers for bidirectional bus interfacing in harsh environments - emphasizing reliability, noise immunity, and drop-in compatibility with legacy TTL systems.
FAQ
What is the operating temperature range for SN74HC640PW?
The SN74HC640PW is rated for operation from –40°C to +85°C, matching the commercial temperature grade of the SN74HC640 family. This range supports deployment in industrial control cabinets, factory automation hardware, and outdoor telemetry enclosures without derating. The device's thermal resistance (RθJA = 83°C/W) requires attention to PCB copper area and airflow in sustained high-load conditions.
Does SN74HC640PW support 3.3V operation?
Yes, SN74HC640PW fully supports 3.3V operation within its 2V–6V supply range. At VCC = 3.3V, it delivers ±3.2 mA output drive (per datasheet interpolation), maintains tpd < 12 ns (CL = 50 pF), and meets VIH/VIL thresholds for clean interfacing with 3.3V CMOS logic. No level-shifting circuitry is needed when connecting to 3.3V microcontrollers or FPGAs.
Is SN74HC640PW pin-compatible with other package variants like SN74HC640N or SN74HC640DWR?
Yes, SN74HC640PW shares identical pinout and electrical functionality with all SN74HC640 variants including PDIP-20 (N), SOIC-20 (DW), and SOP-20 (NS). All variants implement the same DIR/OE control scheme, inverting logic, and I/O mapping. Mechanical differences (body size, lead pitch, thermal profile) require separate PCB footprints, but logic design and firmware remain fully reusable.
What is the maximum capacitive load SN74HC640PW can drive reliably?
SN74HC640PW is characterized up to CL = 150 pF in the datasheet, with tpd increasing to 49 ns (max) at VCC = 6 V. For reliable signal integrity, TI recommends limiting total load (including trace capacitance, probe, and downstream inputs) to ≤100 pF when targeting <25 ns propagation delay. Exceeding 150 pF may cause excessive rise/fall times or output instability, especially at higher VCC.
How does the inverting logic of SN74HC640PW affect system-level timing?
The inverting logic of SN74HC640PW introduces one gate delay of polarity inversion per channel, which is fully accounted for in the published tpd (8 ns typ). System timing analysis must treat the device as a combinational inverter with direction/enable control - no additional setup/hold penalties apply beyond standard HC-series specs. In synchronous designs, this inversion is transparent if protocol layers expect complemented data or use double-inversion schemes.
SN74HC640PW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HC
- Package/Case:
- 20-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Bulk
- 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:
- 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
SN74HC640PW FAQ
1.How can I place an order for SN74HC640PW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HC640PW 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 SN74HC640PW reliable?
The price and inventory of SN74HC640PW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HC640PW is usually 5 days.
3.What payment methods are accepted for SN74HC640PW?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74HC640PW transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74HC640PW?
SN74HC640PW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HC640PW 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 SN74HC640PW?
For technical support, including SN74HC640PW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HC640PW requirements.
6.How does Aetrix verify that SN74HC640PW is sourced from the original manufacturer or authorized distributors?
All SN74HC640PW 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 SN74HC640PW meets industry standards.
7.What is the process for return or replacement of SN74HC640PW?
All SN74HC640PW units undergo pre-shipment inspection (PSI). If there is an issue with SN74HC640PW, 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 SN74HC640PW part is unused and in its original packaging.
Return procedure for SN74HC640PW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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