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onsemi DM74AS652WM
- Part No.:
- DM74AS652WM
- Manufacturer:
- onsemi
- Package:
- 24-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
DM74AS652WM.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 24SOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,448
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Product details
Overview
DM74AS652WM from Fairchild Semiconductor is an octal bus transceiver and register IC with dual-directional data flow control, 90 MHz maximum clock frequency, 3-STATE totem-pole outputs, and industrial-grade operation (0°C to +70°C). It enables real-time or registered data transfer between two 8-bit buses in microprocessor-based systems, I/O expansion interfaces, and buffered memory address/data paths.
For engineers reviewing the DM74AS652WM datasheet, pinout, applications, or equivalent options, key selection factors include its dual-clock edge-triggered D-type register architecture, make-before-break select logic, simultaneous A↔B register loading capability, and SOIC-24 package compatibility with high-density PCB layouts.
Technical Context
The DM74AS652WM integrates two independent 8-bit D-type flip-flop registers clocked by CAB and CBA inputs, supporting concurrent storage of data from both Bus A and Bus B on separate positive clock edges. Its SAB/SBA select controls implement a glitch-free "make before break" transition between real-time and stored data paths.
Four operational modes are enabled via GAB/GBA inputs: real-time A→B, real-time B→A, internal register load from either bus, or registered data output to either bus. All outputs meet TTL-compatible voltage thresholds (VIH = 2.0 V, VIL = 0.8 V) and drive ±48 mA sink/source at VCC = 5 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | Advanced Schottky TTL (AS), compatible with standard TTL and LS logic levels |
| Bus Width | Octal (8-bit) bidirectional data path with independent A and B port I/O |
| Max Clock Frequency | 90 MHz - supports high-speed synchronous bus arbitration in 1980s–1990s microcontroller and minicomputer systems |
| Output Drive | 3-STATE totem-pole: −15 mA source / +48 mA sink - directly drives capacitive bus lines without pull-ups |
| Propagation Delay | 1–11 ns (tPLH/tPHL) - enables sub-10 ns timing margins for 80–100 MHz system clocks |
| Operating Temperature | 0°C to +70°C - commercial-grade specification per datasheet; not rated for −40°C to +85°C (that applies only to DM74AS651 64-grade) |
| Supply Voltage | VCC = 4.5 V to 5.5 V - stable operation across standard 5 V ±10% power rails |
Pinout & Package
DM74AS652WM uses a 24-lead Small Outline Integrated Circuit (SOIC) package per JEDEC MS-013, 0.300" wide (Package Number M24B), with 1.27 mm lead pitch and gull-wing surface-mount terminals.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A1–A8 | Bus A Data I/O | 8-bit bidirectional data port connected to System Bus A; driven by 3-STATE outputs when enabled |
| B1–B8 | Bus B Data I/O | 8-bit bidirectional data port connected to System Bus B; electrically isolated when GAB/GBA disabled |
| CAB | Register Clock A | Positive-edge-triggered clock input controlling storage of Bus A data into internal register |
| CBA | Register Clock B | Positive-edge-triggered clock input controlling storage of Bus B data into internal register |
| SAB | Select A→B Path | HIGH selects stored Bus A data for output to Bus B; LOW passes real-time Bus A data |
| SBA | Select B→A Path | HIGH selects stored Bus B data for output to Bus A; LOW passes real-time Bus B data |
| GAB | Enable A→B Transfer | Active-LOW control enabling data flow (real-time or registered) from Bus A to Bus B |
| GBA | Enable B→A Transfer | Active-LOW control enabling data flow (real-time or registered) from Bus B to Bus A |
| VCC | Power Supply | +4.5 V to +5.5 V supply for all logic and output stages |
| GND | Ground Reference | Common return path for all inputs, outputs, and internal circuitry |
Key Features
| Feature | Design Value |
|---|---|
| Glitch-free multiplexing | "Make before break" SAB/SBA logic prevents transient bus contention during mode switching |
| Dual independent registers | Separate CAB and CBA clocks allow asynchronous capture of Bus A and Bus B data |
| Direct bus driving | 3-STATE totem-pole outputs eliminate need for external pull-up resistors on shared data buses |
| High-speed timing | Sub-10 ns propagation delays support tight setup/hold timing in 8086/8088 and Z80-based designs |
| TTL-compatible interface | VIH = 2.0 V, VIL = 0.8 V, VOH ≥ 2.4 V @ −3 mA ensure interoperability with legacy TTL/LS systems |
Applications
| Microprocessor System Bus Interface | I/O Port Expansion |
|---|---|
Use Scenario: Interfacing an 8086 CPU data bus to peripheral controller or memory-mapped I/O device requiring synchronized data latching. IC Role / Device Role / Timing Role: Acts as bidirectional registered bus transceiver, isolating CPU and peripheral domains while enabling clock-synchronized data capture and forwarding. Use Value: Eliminates external latch and buffer ICs; supports clean timing handshaking via CAB/CBA and GAB/GBA control signals. | Use Scenario: Expanding parallel I/O capability in embedded controllers where GPIO pins are limited and bus bandwidth must be shared among multiple peripherals. IC Role / Device Role / Timing Role: Provides registered 8-bit I/O port with selectable real-time or latched data routing between host bus and peripheral modules. Use Value: Enables deterministic read/write timing across variable-latency peripherals using SAB/SBA and clock edge alignment. |
| Buffered Memory Address/Data Multiplexing | Dual-Bus Arbitration in Industrial Backplanes |
Use Scenario: Separating time-multiplexed address/data bus (e.g., 8085 AD0–AD7) into dedicated address and data paths for static RAM or EPROM access. IC Role / Device Role / Timing Role: Functions as registered transceiver that captures and holds address bits during memory read/write cycles while passing data transparently. Use Value: Removes timing race conditions between address setup and data valid windows; supports reliable 200+ ns memory access timing. | Use Scenario: Managing data exchange between two independent 8-bit backplane buses in programmable logic controller (PLC) chassis or test instrumentation racks. IC Role / Device Role / Timing Role: Serves as configurable bus bridge with independent enable and select controls for deterministic inter-bus communication. Use Value: Allows hot-swappable module synchronization via staggered CAB/CBA clocks and glitch-free SAB/SBA transitions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver and register applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74AS841N | 10-bit bus transceiver with single register and common clock; no independent CAB/CBA or SAB/SBA controls | Lacks dual-register architecture and make-before-break select logic; suited for simpler unidirectional buffering | Choose SN74AS841N only when register independence and glitch-free mode switching are unnecessary |
| DM74AS651WM | Identical pinout and logic function but rated for −40°C to +85°C industrial temperature range | Same functional behavior; differs only in guaranteed operating temperature and qualification testing | Choose DM74AS651WM for extended-temperature deployments; DM74AS652WM remains optimal for commercial-temperature systems |
Compared with SN74AS841N and DM74AS651WM, the DM74AS652WM uniquely delivers dual-clock edge-triggered register control with glitch-free select logic in a commercial-temperature SOIC-24 package - making it the preferred choice for legacy microprocessor bus interfacing where timing determinism and bus isolation are critical.
Availability
DM74AS652WM is available at Aetrix Electronics and suitable for microprocessor bus interface, I/O port expansion, buffered memory addressing, and dual-bus arbitration applications requiring stable component supply and long-term obsolescence management.
Supply support for DM74AS652WM 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
Fairchild Semiconductor was a U.S.-based semiconductor company founded in 1957, known for pioneering TTL, analog, and power management ICs before its acquisition by ON Semiconductor in 2016.
The DM74AS652WM belongs to Fairchild's advanced Schottky TTL (AS) logic family, designed specifically for high-speed, low-glitch bus interfacing in 1980s–1990s computing and industrial control systems.
FAQ
What is the maximum clock frequency supported by the DM74AS652WM?
The DM74AS652WM supports a maximum clock frequency of 90 MHz under recommended operating conditions (VCC = 4.5 V to 5.5 V). This rating is verified across the full commercial temperature range (0°C to +70°C) and applies to both CAB and CBA inputs. The DM74AS652WM achieves this speed using advanced oxide-isolated, ion-implanted Schottky TTL process technology, enabling reliable operation in high-throughput bus architectures without external timing compensation.
Does the DM74AS652WM support simultaneous registration of data from both Bus A and Bus B?
Yes, the DM74AS652WM supports independent and simultaneous registration of data from Bus A and Bus B using separate clock inputs CAB and CBA. When both clocks receive a LOW-to-HIGH transition, their respective 8-bit inputs are captured into dedicated D-type flip-flop registers. Unlike the DM74AS651, the DM74AS652WM allows these clocks to be asserted concurrently without violating timing constraints, as confirmed in the Function Table footnote 2.
What is the difference between DM74AS652WM and DM74AS651WM?
The DM74AS652WM and DM74AS651WM share identical logic functionality, pinout, and electrical specifications, but differ in temperature rating: DM74AS651WM is qualified for −40°C to +85°C (64-grade industrial), while DM74AS652WM is specified for 0°C to +70°C (commercial grade). Both use the same M24B SOIC-24 package and exhibit identical switching characteristics, including 90 MHz fMAX and sub-10 ns propagation delays.
Can the DM74AS652WM drive standard TTL loads directly without pull-up resistors?
Yes, the DM74AS652WM features 3-STATE totem-pole outputs capable of directly driving standard TTL loads without external pull-up components. Its output structure provides strong HIGH-level drive (IOH = −15 mA) and robust LOW-level sink capability (IOL = +48 mA) at VCC = 5 V, meeting TTL voltage thresholds (VOH ≥ 2.4 V, VOL ≤ 0.5 V) and enabling direct connection to bus lines in multi-drop configurations.
Is the DM74AS652WM still manufactured, and what is its obsolescence status?
The DM74AS652WM is no longer in active production by ON Semiconductor (which acquired Fairchild in 2016), but Aetrix Electronics maintains verified legacy inventory with full traceability and extended lifecycle support. Each DM74AS652WM unit supplied undergoes electrical verification per original DS006325 specifications, and Aetrix coordinates long-term availability planning for customers dependent on this component in sustaining engineering and repair programs.
DM74AS652WM Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- 74AS
- Package/Case:
- 24-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- 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:
- 15mA, 48mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-SOP
DM74AS652WM FAQ
1.How can I place an order for DM74AS652WM through Aetrix?
Please submit a Request for Quotation (RFQ) for DM74AS652WM 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 DM74AS652WM reliable?
The price and inventory of DM74AS652WM are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DM74AS652WM is usually 5 days.
3.What payment methods are accepted for DM74AS652WM?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DM74AS652WM transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DM74AS652WM?
DM74AS652WM orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DM74AS652WM 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 DM74AS652WM?
For technical support, including DM74AS652WM datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DM74AS652WM requirements.
6.How does Aetrix verify that DM74AS652WM is sourced from the original manufacturer or authorized distributors?
All DM74AS652WM 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 DM74AS652WM meets industry standards.
7.What is the process for return or replacement of DM74AS652WM?
All DM74AS652WM units undergo pre-shipment inspection (PSI). If there is an issue with DM74AS652WM, 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 DM74AS652WM part is unused and in its original packaging.
Return procedure for DM74AS652WM:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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