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Texas Instruments SN74BCT245DBR
- Part No.:
- SN74BCT245DBR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
SN74BCT245DBR.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 20SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,203
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Product details
Overview
SN74BCT245DBR from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data transfer between A and B buses in TTL-level systems. It features direction control (DIR), output enable (OE), 8-bit bidirectional channels, 5 V supply operation, and supports up to 64 mA sink current on B-port outputs. It is commonly used in memory address register buffering and legacy bus isolation.
For engineers reviewing the SN74BCT245DBR datasheet, SN74BCT245DBR pinout, SN74BCT245DBR application, or SN74BCT245DBR equivalent, key selection criteria include 3-state bus driving capability, TTL-compatible input thresholds, propagation delay under 7 ns, thermal resistance of 70°C/W in SSOP-20, and compatibility with 50 pF load switching conditions.
Technical Context
The SN74BCT245DBR implements a dual-bus, direction-controllable transceiver architecture using bipolar TTL circuitry. Its DIR input selects data flow direction (A→B or B→A), while OE independently disables all outputs into high-impedance state - enabling true bus isolation without signal contention.
It operates strictly at 4.5–5.5 V supply, with guaranteed VIH ≥ 2 V and VIL ≤ 0.8 V for TTL-level interfacing. Output drive strength is asymmetric: B-port sinks up to 64 mA (IOL), while A-port sinks 24 mA, reflecting its typical use as a peripheral-to-system bus driver.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - mandates regulated 5 V rail; not compatible with 3.3 V logic domains. |
| Propagation Delay | ≤ 7 ns (tPLH/tPHL) - enables reliable operation in 100+ MHz bus environments with 50 pF load. |
| B-Port IOL | 64 mA - sufficient to drive eight TTL inputs or terminate stub-loaded parallel buses. |
| 3-State Enable/Disable Time | tPZH/tPLZ ≤ 10.9 ns - ensures fast bus turnaround and avoids glitches during direction switching. |
| Thermal Resistance θJA | 70°C/W (SSOP-20 package) - requires moderate PCB copper area for sustained 90 mA ICC peak current. |
| ESD Rating | ±2000 V HBM - meets industrial-grade handling requirements without additional protection circuitry. |
Pinout & Package
SN74BCT245DBR uses a 20-pin SSOP (Shrink Small Outline Package) with 0.65 mm pitch, 7.4 mm × 5.3 mm body, and 2.0 mm max height. Pin 1 is located at top-left corner with index marking (see DB0020A outline).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (DIR) | Direction Control Input | Low = B→A data flow; High = A→B data flow - determines real-time bus directionality. |
| 2–9 (A1–A8) | A-Side Data I/O | Bidirectional TTL I/O pins connected to local subsystem bus (e.g., microcontroller address/data lines). |
| 10 (GND) | Ground Reference | Primary return path for all I/O and supply currents; must be low-inductance connection. |
| 11 (VCC) | Power Supply | +5 V supply input; requires local 0.1 µF ceramic decoupling adjacent to pin. |
| 12 (OE) | Output Enable Input | Low = outputs active; High = all A/B pins enter high-Z - critical for bus arbitration and hot-swap isolation. |
| 13–20 (B1–B8) | B-Side Data I/O | Bidirectional TTL I/O pins connected to main system bus (e.g., memory or peripheral expansion bus). |
Key Features
| Feature | Design Value |
|---|---|
| Asymmetric Output Drive | B-port delivers 64 mA sink vs. A-port's 24 mA - optimized for driving heavier system-side loads from lighter controller-side buses. |
| Independent DIR and OE Controls | Enables simultaneous direction setting and output gating - supports dynamic bus sharing without race conditions. |
| TTL-Compatible Thresholds | VIH ≥ 2 V and VIL ≤ 0.8 V - ensures interoperability with legacy 5 V TTL, LSTTL, and BCT logic families. |
| Fast 3-State Transition | tPZH/tPLZ ≤ 10.9 ns - minimizes bus contention window during enable/disable cycles in multiplexed architectures. |
| SSOP-20 Thermal Profile | θJA = 70°C/W - allows operation up to 70°C ambient at full drive with standard 2-layer PCB copper pour. |
Applications
| Memory Address Buffering | Legacy ISA Bus Isolation |
|---|---|
|
Use Scenario: Isolating CPU address lines from multiple memory banks with shared address decoding. IC Role / Device Role / Timing Role: Bidirectional address transceiver that buffers and isolates 8-bit address segments (e.g., A0–A7) between processor and SRAM/ROM chips. Use Value: Prevents loading-induced timing skew and enables independent power cycling of memory modules without affecting CPU bus integrity. |
Use Scenario: Interfacing modern microcontrollers to vintage ISA expansion slots requiring strict 5 V TTL signaling. IC Role / Device Role / Timing Role: Level-shifting and direction-controlled data path between 32-bit host bus and 16-bit ISA peripherals. Use Value: Provides cycle-accurate 3-state control synchronized with ISA IOR/IOW strobes, eliminating bus contention during DMA transfers. |
| Industrial Backplane Interface | Test Equipment Signal Routing |
|
Use Scenario: Managing bidirectional data flow across modular backplanes in programmable logic controllers (PLCs). IC Role / Device Role / Timing Role: Reconfigurable bus segment repeater that routes data between CPU module and I/O carrier boards based on slot ID. Use Value: Enables hot-plug detection via OE-controlled isolation and supports deterministic latency (<7 ns) for real-time I/O scanning. |
Use Scenario: Dynamic signal path configuration in automated test equipment (ATE) where DUT interfaces require re-routable 8-bit data lanes. IC Role / Device Role / Timing Role: Programmable signal switch matrix element controlled by FPGA GPIO to establish custom stimulus/response paths. Use Value: Eliminates mechanical relays for signal routing; achieves sub-10 ns path reconfiguration with no contact wear or bounce artifacts. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LVC245A | 3.3 V only (1.65–3.6 V), CMOS process, lower drive (24 mA), 3.5 ns max tPD | Requires level translation for 5 V systems; unsuitable for direct TTL bus loading | Select when migrating to 3.3 V domains with lower power and higher speed needs. |
| SN74ABT245 | 5 V operation, higher drive (B-port IOL = 64 mA), faster tPD (≤5.5 ns), same pinout | Improved noise immunity and reduced ground bounce due to ABT-series output structure | Drop-in upgrade for SN74BCT245DBR where tighter timing margins or EMI robustness are required. |
Compared with SN74LVC245A, SN74BCT245DBR provides native 5 V TTL compatibility and stronger bus drive; compared with SN74ABT245, it offers identical functionality at slightly relaxed timing but broader legacy system acceptance.
Availability
SN74BCT245DBR is available at Aetrix Electronics and suitable for memory address buffering, legacy ISA bus isolation, industrial backplane interface, and test equipment signal routing requiring stable component supply and long-term industrial lifecycle support.
Supply support for SN74BCT245DBR 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 industrial, automotive, and communications markets.
The SN74BCT245DBR belongs to TI's legacy BCT logic family, engineered specifically for robust 5 V TTL bus interfacing in industrial control, instrumentation, and retro-computing applications where reliability and backward compatibility are critical.
FAQ
What is the maximum operating temperature for SN74BCT245DBR?
The SN74BCT245DBR is rated for operation from 0°C to +70°C ambient temperature. This commercial-grade specification aligns with its SSOP-20 packaging and intended use in non-military industrial and computing equipment. Exceeding 70°C may cause parametric shift in VOH/VOL or increased ICCZ leakage, and is not guaranteed per datasheet limits.
Can SN74BCT245DBR operate with a 3.3 V supply?
No, SN74BCT245DBR requires a minimum supply voltage of 4.5 V and is specified only for 4.5–5.5 V operation. Applying 3.3 V will result in undefined logic states, insufficient output drive, and potential failure to meet VIH/VIL thresholds. For 3.3 V systems, consider SN74LVC245A instead.
Is SN74BCT245DBR pin-compatible with SN74ABT245?
Yes, SN74BCT245DBR and SN74ABT245 share identical 20-pin SSOP (DB) package dimensions, pin numbering, and functional pin assignments - including DIR, OE, A1–A8, B1–B8, VCC, and GND. This enables direct PCB replacement without layout changes.
What is the purpose of the DIR and OE pins on SN74BCT245DBR?
DIR controls data direction: logic high enables A→B transmission; logic low enables B→A transmission. OE independently gates all outputs: logic low enables driving; logic high places all A/B pins in high-impedance state. Together, they allow dynamic bus arbitration and conflict-free multi-master operation in SN74BCT245DBR-based systems.
Does SN74BCT245DBR support hot-swap insertion?
SN74BCT245DBR supports hot-swap insertion only when OE is held high (outputs disabled) during insertion, and power sequencing ensures VCC ramps before signal lines become active. Its ±2000 V HBM ESD rating aids handling robustness, but no built-in hot-swap current limiting is provided - external series resistors or dedicated hot-swap controllers are recommended for live backplane use.
SN74BCT245DBR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74BCT
- Package/Case:
- 20-SSOP (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Logic Type:
- Transceiver, Non-Inverting
- Number of Elements:
- 1
- Number of Bits per Element:
- 8
- Input Type:
- -
- Output Type:
- 3-State
- Current - Output High, Low:
- 3mA, 24mA; 15mA, 64mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SSOP
SN74BCT245DBR FAQ
1.How can I place an order for SN74BCT245DBR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74BCT245DBR 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 SN74BCT245DBR reliable?
The price and inventory of SN74BCT245DBR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74BCT245DBR is usually 5 days.
3.What payment methods are accepted for SN74BCT245DBR?
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4.How is shipping managed for SN74BCT245DBR?
SN74BCT245DBR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74BCT245DBR 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 SN74BCT245DBR?
For technical support, including SN74BCT245DBR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74BCT245DBR requirements.
6.How does Aetrix verify that SN74BCT245DBR is sourced from the original manufacturer or authorized distributors?
All SN74BCT245DBR 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 SN74BCT245DBR meets industry standards.
7.What is the process for return or replacement of SN74BCT245DBR?
All SN74BCT245DBR units undergo pre-shipment inspection (PSI). If there is an issue with SN74BCT245DBR, 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 SN74BCT245DBR part is unused and in its original packaging.
Return procedure for SN74BCT245DBR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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