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Texas Instruments SN74AHC245DBR
- Part No.:
- SN74AHC245DBR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
SN74AHC245DBR.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 20SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,991
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Product details
Overview
SN74AHC245DBR from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data transfer between two 8-bit buses. It operates from 2 V to 5.5 V, supports direction control via DIR pin and output enable via OE pin, and delivers propagation delays as low as 4 ns at 5 V - enabling reliable level-shifting and bus isolation in mixed-voltage systems such as 5 V ↔ 3.3 V microcontroller interfaces.
For engineers reviewing the SN74AHC245DBR datasheet, SN74AHC245DBR pinout, SN74AHC245DBR application, or SN74AHC245DBR equivalent, key selection criteria include its 20-pin SSOP package, ±25 mA output drive per channel, 3-state isolation capability, and verified operation across –40°C to +125°C industrial temperature range.
Technical Context
The SN74AHC245DBR implements dual-bus bidirectional communication using a single DIR input to select data flow direction (A→B or B→A), while OE independently controls 3-state output enable/disable. Its CMOS AHC logic family ensures rail-to-rail output swing, overvoltage-tolerant inputs (up to 5.5 V), and slow edge rates to suppress output ringing.
Functional modes are strictly defined by OE and DIR logic levels: OE = L enables bidirectional transfer (DIR = L → B→A; DIR = H → A→B); OE = H forces all outputs into high-impedance state regardless of DIR. No internal latching or clocking is involved - operation is purely combinatorial and asynchronous.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 2 V to 5.5 V - supports direct interfacing between 3.3 V and 5 V domains without external level shifters. |
| Propagation Delay (tPLH/tPHL) | 4 ns (min) at VCC = 5 V, CL = 15 pF - enables high-speed bus handshaking in real-time embedded systems. |
| Output Drive | ±8 mA at VCC = 5 V - sufficient to drive standard TTL loads and moderate-capacitance PCB traces without signal degradation. |
| Input Voltage Tolerance | Up to 5.5 V on all I/O pins - allows safe down-translation from 5 V logic to 3.3 V microcontrollers. |
| Operating Temperature | –40°C to +125°C - qualified for industrial and automotive under-hood applications requiring extended thermal robustness. |
| ESD Rating | 1500 V HBM - meets standard handling requirements for automated assembly and field-replaceable modules. |
Pinout & Package
SN74AHC245DBR uses a 20-pin SSOP (Shrink Small Outline Package) with 0.65 mm lead pitch, body size 7.20 mm × 5.30 mm, and JEDEC MO-153 compliant footprint. Thermal resistance RθJA = 113.1°C/W enables stable operation at up to 125°C ambient with minimal heatsinking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| DIR (Pin 1) | Direction Control Input | Determines data flow direction: logic HIGH enables A→B transfer; LOW enables B→A transfer. |
| OE (Pin 19) | Output Enable Input | Active-LOW control: when HIGH, all A/B outputs enter high-impedance state for bus isolation. |
| A1–A8 (Pins 2–9) | Port A I/O | Eight bidirectional data lines connected to first bus; driven or sensed depending on DIR and OE state. |
| B1–B8 (Pins 11–18) | Port B I/O | Eight bidirectional data lines connected to second bus; complementary to Port A in direction-controlled transfer. |
| GND (Pin 10) | Ground Reference | Primary return path for all I/O and supply currents; must be low-impedance connection to system ground plane. |
| VCC (Pin 20) | Power Supply | Single-supply rail supporting full 2–5.5 V operating range; requires local 0.1 µF bypass capacitor. |
Key Features
| Feature | Design Value |
|---|---|
| Asynchronous Bidirectional Transfer | Enables real-time, clock-free data exchange between independent buses - eliminates timing constraints from master clock synchronization. |
| Overvoltage-Tolerant Inputs | Accepts up to 5.5 V on all A/B/DIR/OE pins regardless of VCC setting - simplifies mixed-voltage board design and prevents damage during power sequencing. |
| Controlled Edge Rates | Intentionally slowed rise/fall times minimize overshoot/undershoot on PCB traces - reduces EMI and eliminates need for external series termination resistors. |
| High-Impedance Isolation | OE-driven 3-state outputs provide true electrical disconnection between buses - critical for hot-swap, power-gating, and multi-master arbitration schemes. |
| Industrial Temperature Range | Guaranteed functionality from –40°C to +125°C - validated for use in telecom infrastructure, industrial PLCs, and automotive control units. |
Applications
| Microcontroller Bus Interface | Legacy Peripheral Integration |
|---|---|
Use Scenario: Interfacing a 3.3 V ARM Cortex-M microcontroller with legacy 5 V parallel peripherals (e.g., LCD controllers, EEPROMs, or GPIO expanders). IC Role / Device Role / Timing Role: Level-translating bidirectional bus transceiver that isolates voltage domains while preserving signal integrity and timing margins. Use Value: Eliminates discrete resistor-divider networks or dedicated level-shifters, reducing BOM count and layout area while maintaining <4 ns propagation delay. | Use Scenario: Connecting modern low-voltage FPGAs to older 5 V ISA or PC/104 expansion buses in industrial test equipment. IC Role / Device Role / Timing Role: Asynchronous bus bridge providing direction-controlled data routing and OE-based bus arbitration. Use Value: Enables seamless integration without modifying FPGA I/O standards or adding complex glue logic - supports hot-plug detection via OE control. |
| Server Memory Subsystem | Wearable Health Data Hub |
Use Scenario: Isolating DDR memory controller signals from diagnostic or debug interface buses in enterprise servers. IC Role / Device Role / Timing Role: High-reliability 3-state buffer enabling dynamic bus segmentation during firmware updates or memory training sequences. Use Value: Prevents signal contention during reconfiguration; ±25 mA drive ensures clean edges across long backplane traces at 100+ MHz effective data rates. | Use Scenario: Managing bidirectional sensor data flow between ultra-low-power 1.8 V health SoC and 3.3 V analog front-end (AFE) or display driver in wearable patches. IC Role / Device Role / Timing Role: Low-quiescent-current (4 µA typical ICC) bus transceiver enabling duty-cycled sensor polling without voltage translation losses. Use Value: Extends battery life by minimizing static power draw while maintaining sub-10 ns timing accuracy for synchronized ECG/PPG sampling. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LVC245APWR | Lower VCC range (1.65–3.6 V); 3.3 V only; faster tPLH (2.5 ns @ 3.3 V) | Not suitable for 5 V systems; requires separate 5 V→3.3 V level shifters if interfacing with legacy hardware | Select when full system operates at 3.3 V and maximum speed is prioritized over voltage flexibility. |
| 74AVCH245PW | Supports 0.8–3.6 V dual-supply operation; higher drive (±24 mA); no 5 V tolerance on inputs | Requires strict 3.3 V domain isolation; unsuitable for direct 5 V bus connection without external protection | Choose for ultra-low-voltage portable designs where dynamic voltage scaling is required and 5 V compatibility is unnecessary. |
Compared with SN74LVC245APWR and 74AVCH245PW, the SN74AHC245DBR uniquely balances 2–5.5 V operation, 5.5 V input tolerance, and industrial temperature rating - making it the only option among the three qualified for mixed-voltage industrial control and server backplane applications without supplemental circuitry.
Availability
SN74AHC245DBR is available at Aetrix Electronics and suitable for industrial automation, telecom infrastructure, and embedded computing applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for SN74AHC245DBR 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 delivering analog, embedded processing, and connectivity solutions for industrial, automotive, and personal electronics markets.
The SN74AHC245DBR belongs to TI's AHC logic family - engineered for high-speed, low-power, mixed-voltage bus interfacing in mission-critical systems where reliability and wide operating margins are essential.
FAQ
What is the maximum output current per pin for the SN74AHC245DBR?
The SN74AHC245DBR supports ±25 mA continuous output current per pin at VCC = 5 V, with total device current limited to ±75 mA across all outputs. This rating ensures robust drive capability for standard TTL loads and moderate PCB trace capacitance while maintaining signal fidelity and thermal stability in the SSOP package.
Can the SN74AHC245DBR safely interface a 5 V microcontroller with a 3.3 V FPGA?
Yes - the SN74AHC245DBR accepts input voltages up to 5.5 V on all I/O and control pins regardless of VCC setting, enabling direct 5 V → 3.3 V down-translation. When powered at 3.3 V, it drives compatible 3.3 V logic levels while protecting the FPGA inputs from overvoltage, making it ideal for mixed-domain MCU-FPGA interconnects.
What is the recommended bypass capacitor for the SN74AHC245DBR VCC pin?
A 0.1 µF ceramic capacitor placed as close as possible to the VCC pin (Pin 20) is recommended for the SN74AHC245DBR. For improved noise suppression across frequency bands, TI advises paralleling this with a 1 µF capacitor. Both must connect directly to the local ground plane with minimal trace length to maintain stable supply rail integrity during fast output transitions.
Does the SN74AHC245DBR require pull-up resistors on DIR or OE pins?
OE should be pulled up to VCC via a resistor (e.g., 10 kΩ) during power-up/down to ensure outputs remain in high-impedance state until firmware initializes control logic. DIR has no default requirement - its state determines data direction and may be driven directly by a GPIO or tied statically; floating DIR is not permitted and will cause undefined bus behavior.
Is the SN74AHC245DBR pin-compatible with other packages in the SN74AHC245 family?
No - the SN74AHC245DBR (SSOP-20) shares identical pin functions and logic behavior with other SN74AHC245 variants but is not mechanically pin-compatible with SOIC (DW), TSSOP (PW), or VSSOP (DGS) packages due to differing pad layouts, lead pitches, and thermal pad presence. Board redesign is required when substituting between these packages.
SN74AHC245DBR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHC
- 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:
- 8mA, 8mA
- Voltage - Supply:
- 2V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SSOP
SN74AHC245DBR FAQ
1.How can I place an order for SN74AHC245DBR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHC245DBR 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 SN74AHC245DBR reliable?
The price and inventory of SN74AHC245DBR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHC245DBR is usually 5 days.
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4.How is shipping managed for SN74AHC245DBR?
SN74AHC245DBR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHC245DBR 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 SN74AHC245DBR?
For technical support, including SN74AHC245DBR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHC245DBR requirements.
6.How does Aetrix verify that SN74AHC245DBR is sourced from the original manufacturer or authorized distributors?
All SN74AHC245DBR 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 SN74AHC245DBR meets industry standards.
7.What is the process for return or replacement of SN74AHC245DBR?
All SN74AHC245DBR units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHC245DBR, 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 SN74AHC245DBR part is unused and in its original packaging.
Return procedure for SN74AHC245DBR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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