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onsemi MC74AC648DW
- Part No.:
- MC74AC648DW
- Manufacturer:
- onsemi
- Package:
- 24-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
MC74AC648DW.pdf
- Description:
- IC TXRX NON-INVERT 6V 24SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:900
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Product details
Overview
MC74AC648DW from ON Semiconductor (formerly Motorola) is an octal registered bus transceiver with 3-state outputs and inverting logic function, implementing dual-directional data flow between A and B buses via independent D-type flip-flop registers clocked by CAB/CBA inputs. It supports real-time or registered transfer modes, offers ±24 mA output drive, operates at 2.0–6.0 V supply, and is housed in a 24-pin SOIC package. It is used in bidirectional data buffering and register-controlled bus isolation in industrial control backplanes.
For engineers reviewing the MC74AC648DW datasheet, pinout, applications, or equivalent options, key selection criteria include its dual-register architecture, 3-state enable timing (tPZH/tPLZ < 12 ns @ 5 V), inverting output polarity, bus-to-bus propagation delay of 4.0–7.5 ns, and compatibility with both 3.3 V and 5 V logic systems.
Technical Context
This device integrates two independent 8-bit register banks (A and B), each with dedicated clock (CAB/CBA) and transmit/receive (SAB/SBA) controls, enabling four distinct data-handling modes: real-time A→B, real-time B→A, stored A→B, and stored B→A. The DIR and G pins jointly manage direction and 3-state output enable, while all register loads occur on LOW-to-HIGH clock transitions.
Its inverting 3-state outputs support high-fanout bus driving with guaranteed VOH ≥ 2.9 V (at VCC = 3.0 V, IOH = –24 mA) and VOL ≤ 0.44 V (at VCC = 5.5 V, IOL = 24 mA). Input thresholds are TTL-compatible for AC variants (VIH = 2.1 V min @ 3.0 V), and it meets commercial temperature range (–40°C to +85°C) operation with ICC ≤ 80 µA quiescent current.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Function | Octal registered bus transceiver with inverting 3-state outputs |
| Supply Voltage Range | 2.0 V to 6.0 V - supports mixed-voltage system interfacing |
| Output Drive | ±24 mA - drives standard TTL/CMOS loads without external buffers |
| Propagation Delay | 4.0 ns (min) to 7.5 ns (max) bus-to-bus @ 5.0 V - enables high-speed synchronous data routing |
| Enable/Disable Time | tPZH/tPLZ ≤ 9.0 ns @ 5.0 V - ensures fast bus arbitration and glitch-free switching |
| Input Thresholds | VIH = 2.1 V min @ 3.0 V - compatible with 3.3 V LVTTL and 5 V TTL logic families |
| Operating Temperature | –40°C to +85°C - qualified for industrial-grade embedded applications |
Pinout & Package
MC74AC648DW is packaged in a 24-pin plastic SOIC (Small Outline Integrated Circuit), case 751E-04, with 300-mil body width and standard JEDEC MS-013 footprint. Pin pitch is 1.27 mm, and package height is 2.65 mm max.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (CAB) | Register A clock input | LOW-to-HIGH transition loads A0–A7 data into register A |
| 2 (SAB) | A→B transmit control | Active HIGH enables real-time or stored A→B transfer |
| 3 (DIR) | Direction control | HIGH selects A→B mode; LOW selects B→A mode |
| 4–11 (A0–A7) | Register A I/O pins | Bidirectional data lines for A bus; register outputs are inverted |
| 12 (GND) | Ground reference | Primary power return path for all internal logic and I/O |
| 13–20 (B0–B7) | Register B I/O pins | Bidirectional data lines for B bus; register outputs are inverted |
| 21 (G) | Output enable | Active LOW enables 3-state outputs; HIGH forces high-impedance |
| 22 (SBA) | B→A transmit control | Active HIGH enables real-time or stored B→A transfer |
| 23 (CBA) | Register B clock input | LOW-to-HIGH transition loads B0–B7 data into register B |
| 24 (VCC) | Positive supply | Single 2.0–6.0 V supply powers all logic and output stages |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent register banks | Enables concurrent storage and routing of A- and B-bus data without interference |
| Multiplexed real-time/register transfer | Four selectable modes (Figs. 1–4) simplify bus arbitration and pipeline staging |
| Inverting 3-state outputs | Ensures signal integrity in shared-bus environments and prevents contention during state changes |
| Wide supply voltage range (2.0–6.0 V) | Supports direct interface with 3.3 V microcontrollers and legacy 5 V peripherals |
| Low propagation skew | Typical tPLH/tPHL matching ≤ 1.5 ns across channels improves timing margin in parallel buses |
Applications
| Industrial Backplane Interface | Microcontroller Bus Expansion |
|---|---|
Use Scenario: Isolating and synchronizing data between CPU and peripheral modules on a modular PLC rack. IC Role / Device Role / Timing Role: Registered transceiver managing time-aligned transfers between address/data buses and I/O module registers. Use Value: Eliminates metastability risk during hot-swap events and provides deterministic setup/hold timing via clocked registers. |
Use Scenario: Extending GPIO or data bus capability of an ARM Cortex-M4 MCU with external SRAM and FPGA co-processor. IC Role / Device Role / Timing Role: Bidirectional buffer with register hold capability, decoupling MCU timing from slower memory access cycles. Use Value: Enables zero-wait-state operation for burst reads/writes by latching addresses and data on clock edges. |
| Test Equipment Data Acquisition | Legacy System Protocol Bridge |
Use Scenario: Capturing parallel sensor data streams (e.g., 8-channel ADC outputs) before serial conversion. IC Role / Device Role / Timing Role: Synchronized sampling node that stores analog front-end data on system clock edge for controlled readout. Use Value: Provides simultaneous capture across all 8 channels with sub-10 ns inter-channel skew. |
Use Scenario: Interfacing a modern 3.3 V SoC to a legacy 5 V ISA bus peripheral in medical diagnostic hardware. IC Role / Device Role / Timing Role: Level-shifting, direction-controlled transceiver with register hold to match ISA timing requirements. Use Value: Meets ISA's 600 ns address setup time via stored register mode while maintaining 3.3 V core logic compatibility. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar registered bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ACT648DW | TTL-compatible inputs (VIH = 2.0 V min @ 5 V); slightly higher ICC (≤100 µA) | Better noise immunity in noisy industrial environments; identical pinout and function | Preferred when interfacing with legacy 5 V TTL sources requiring tighter input threshold margins. |
| 74LCX648M | Lower VCC range (2.0–3.6 V only); non-inverting outputs; 3.6 V absolute max rating | Designed for 3.3 V-only systems; lacks 5 V tolerance and register inversion behavior | Select only for pure 3.3 V domains where inversion must be implemented externally and 5 V compatibility is unnecessary. |
Compared with MC74AC648DW, SN74ACT648DW offers improved input noise rejection but consumes more quiescent current, while 74LCX648M reduces power and voltage overhead at the cost of 5 V interoperability and native inversion - making MC74AC648DW the optimal choice for mixed-voltage, register-synchronized, inverting bus interfaces.
Availability
MC74AC648DW is available at Aetrix Electronics and suitable for industrial backplane interfaces, microcontroller bus expansion, test equipment data acquisition, and legacy system protocol bridging requiring stable component supply across extended product lifecycles.
Supply support for MC74AC648DW 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
ON Semiconductor is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, and IoT applications.
The MC74AC648DW belongs to ON Semiconductor's legacy logic portfolio, originally developed by Motorola for high-reliability registered data routing in industrial control and instrumentation systems.
FAQ
What is the logic polarity of MC74AC648DW outputs?
The MC74AC648DW features inverting 3-state outputs: data appearing at A0–A7 or B0–B7 outputs is logically inverted relative to the corresponding register input. This is confirmed in the logic symbol, function table, and "INVERTING" designation in the device title. The inversion applies to both real-time and registered transfer paths, and cannot be disabled.
Can MC74AC648DW operate reliably at 3.3 V supply?
Yes, MC74AC648DW is fully specified for 3.3 V operation: DC characteristics guarantee VIH ≥ 2.1 V and VOL ≤ 0.44 V at VCC = 3.3 V (interpolated from 3.0 V/4.5 V data), and AC timing (e.g., tPLH bus-to-bus = 6.0 ns typ) remains valid. Its 2.0–6.0 V supply range makes it suitable for direct integration into 3.3 V systems without level shifters.
How does the DIR pin interact with SAB and SBA in MC74AC648DW?
In MC74AC648DW, DIR selects primary direction (HIGH = A→B, LOW = B→A), while SAB and SBA independently gate data flow: SAB enables A→B transfers (real-time or stored), and SBA enables B→A transfers. Both SAB and SBA must be HIGH for their respective paths to activate; DIR alone does not enable outputs - G must also be LOW and the relevant clock edge must occur.
What is the maximum clock frequency supported by MC74AC648DW?
MC74AC648DW does not specify a maximum clock frequency directly, but minimum clock pulse width is 3.0 ns (typ) at VCC = 3.3 V and 3.0 ns (min) at VCC = 5.0 V. Accounting for setup/hold (ts = 3.5 ns, th = 0 ns min), practical maximum clock rate is ~100 MHz for reliable register loading - validated by tPLH/tPHL propagation delays under 12 ns and AC operating requirements.
Is MC74AC648DW pin-compatible with MC74ACT648DW?
Yes, MC74AC648DW and MC74ACT648DW share identical pinout, package (SOIC-24), and functional block diagram. Their only differences are input threshold specifications (AC: VIH = 2.1 V min @ 3.0 V; ACT: VIH = 2.0 V min @ 4.5 V) and AC timing margins. Both devices may be substituted on the same PCB without layout changes, provided system voltage and noise environment align with the chosen variant's specs.
MC74AC648DW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- 74AC
- Package/Case:
- 24-SOIC (0.295", 7.50mm Width)
- Packaging:
- Bulk
- Product Status:
- Active
- Logic Type:
- Transceiver, Non-Inverting
- Number of Elements:
- 1
- Number of Bits per Element:
- 8
- Input Type:
- -
- Output Type:
- -
- Current - Output High, Low:
- 24mA, 24mA
- Voltage - Supply:
- 2V ~ 6V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-SOIC
MC74AC648DW FAQ
1.How can I place an order for MC74AC648DW through Aetrix?
Please submit a Request for Quotation (RFQ) for MC74AC648DW 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 MC74AC648DW reliable?
The price and inventory of MC74AC648DW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC74AC648DW is usually 5 days.
3.What payment methods are accepted for MC74AC648DW?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC74AC648DW transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC74AC648DW?
MC74AC648DW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC74AC648DW 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 MC74AC648DW?
For technical support, including MC74AC648DW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC74AC648DW requirements.
6.How does Aetrix verify that MC74AC648DW is sourced from the original manufacturer or authorized distributors?
All MC74AC648DW 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 MC74AC648DW meets industry standards.
7.What is the process for return or replacement of MC74AC648DW?
All MC74AC648DW units undergo pre-shipment inspection (PSI). If there is an issue with MC74AC648DW, 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 MC74AC648DW part is unused and in its original packaging.
Return procedure for MC74AC648DW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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