My Inquiry
My Account
onsemi DM74LS245WM
- Part No.:
- DM74LS245WM
- Manufacturer:
- onsemi
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
DM74LS245WM.pdf
- Description:
- IC TXRX NON-INVERT 5.25V 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,440
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
DM74LS245WM from Fairchild Semiconductor is a 3-STATE octal bus transceiver in 20-pin SOIC (M20B) package, supporting bidirectional asynchronous data transfer between A and B buses with direction control (DIR) and output enable (G). It delivers 24 mA sink and −15 mA source drive, 8 ns typical port-to-port propagation delay, and operates across 0°C to +70°C. Used in legacy industrial backplane interfaces and TTL-level system interconnects.
For engineers reviewing the DM74LS245WM datasheet, pinout, applications, or equivalent options, key selection criteria include 3-STATE bus isolation timing (tPZL/tPHZ ≤ 45 ns), hysteresis-enhanced noise immunity (0.2–0.4 V), PNP input structure for reduced DC loading, and compatibility with standard LS-TTL logic levels (VIH = 2.0 V, VIL = 0.8 V).
Technical Context
The DM74LS245WM implements dual-bus bidirectional communication using a single DIR input to select data flow direction (A→B or B→A) and an active-low G input to enable/disable all outputs into high-impedance state. Its internal architecture uses PNP-based input stages to minimize bus loading and incorporates Schmitt-trigger hysteresis on all A/B bus inputs.
Timing behavior is defined by propagation delays (tPLH/tPHL ≤ 17 ns at CL = 150 pF), output enable/disable times (tPZL/tPZH ≤ 45 ns, tPLZ/tPHZ ≤ 25 ns), and guaranteed operation under recommended conditions: VCC = 4.75–5.25 V, TA = 0–70°C, with VIH ≥ 2.0 V and VIL ≤ 0.8 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.75 V to 5.25 V - Ensures stable operation within standard LS-TTL supply tolerance. |
| IOL / IOH | 24 mA sink / −15 mA source - Drives standard TTL loads directly without external buffers. |
| Propagation Delay | 12–17 ns - Supports synchronous bus handshaking up to ~50 MHz effective throughput. |
| Hysteresis (VT+−VT−) | 0.2–0.4 V - Increases noise immunity on shared bus lines in electrically noisy environments. |
| Off-State Leakage | ±200 µA - Maintains bus integrity during 3-STATE isolation with minimal leakage coupling. |
| Input Clamp Voltage | −1.5 V - Protects inputs against negative transients up to 1.5 V below ground. |
| Operating Temperature | 0°C to +70°C - Qualified for commercial-grade embedded control and instrumentation systems. |
Pinout & Package
DM74LS245WM is housed in a 20-lead Small Outline Integrated Circuit (SOIC) package per JEDEC MS-013, 0.300-inch body width (Package Number M20B), with standard gull-wing lead form and 1.27 mm pitch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (G) | Output Enable (active low) | Asserting LOW enables transceiver; HIGH forces all A/B outputs into high-impedance state. |
| 2–9 (A1–A8) | Bus A I/O terminals | Connect to source bus; direction determined by DIR; driven by internal 3-STATE outputs when enabled. |
| 10 (GND) | Ground reference | Primary return path for all internal logic and I/O current; must be low-impedance. |
| 11–18 (B1–B8) | Bus B I/O terminals | Connect to destination bus; data flows A→B or B→A depending on DIR state. |
| 19 (DIR) | Direction Control input | LOW selects B→A transfer; HIGH selects A→B transfer; referenced to VCC/GND logic thresholds. |
| 20 (VCC) | Positive supply | 5 V nominal supply; decoupling capacitor required near pin for switching noise suppression. |
Key Features
| Feature | Design Value |
|---|---|
| Bi-directional bus transceiver | Single device replaces two unidirectional buffers, reducing board area and interconnect complexity in backplane designs. |
| 3-STATE outputs | Enables true bus sharing among multiple devices without contention, critical for multi-master TTL systems. |
| PNP input structure | Reduces steady-state DC loading on driving bus lines by limiting input current to ≤0.1 mA per pin. |
| Hysteresis on all bus inputs | Improves noise rejection on long or unterminated traces, preventing false switching in industrial environments. |
| Standard LS-TTL compatible | Directly interfaces with 74LS, 74ALS, and 74F families without level-shifting circuitry. |
Applications
| Industrial Backplane Interconnect | Legacy Computer System Expansion |
|---|---|
Use Scenario: Connecting CPU and peripheral modules across a 200 mm PCB backplane with shared address/data lines. IC Role / Device Role / Timing Role: Bidirectional data routing between master and slave slots; DIR controlled by slot-select decoder, G synchronized to bus grant. Use Value: 8-bit parallel transfer with <25 ns disable time ensures clean bus release before next cycle, minimizing arbitration latency. | Use Scenario: Adding ISA-compatible I/O cards to vintage PC architectures requiring TTL-level bus bridging. IC Role / Device Role / Timing Role: Level-translating and isolating expansion bus segments while preserving LS-TTL voltage thresholds and fanout. Use Value: PNP inputs reduce cumulative loading on motherboard bus drivers, enabling reliable operation with up to 8 add-in cards. |
| Test Equipment Bus Interface | Programmable Logic Controller (PLC) I/O Module |
Use Scenario: Isolating DUT interface bus from controller logic in automated test systems with mixed-voltage subsystems. IC Role / Device Role / Timing Role: Controlled data mirroring between microcontroller and fixture electronics; G tied to test sequence state machine. Use Value: 0.4 V max VOL at 12 mA ensures robust LOW detection even with 20 cm ribbon cable runs and contact resistance. | Use Scenario: Interfacing field I/O terminals to central PLC processor via isolated 8-bit parallel data paths. IC Role / Device Role / Timing Role: Buffering and direction-switching for status/command words between CPU and local I/O ASICs. Use Value: Hysteresis (0.2–0.4 V) prevents spurious reads from EMI-coupled sensor wiring in factory-floor environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LS245N | Same electrical specs and pinout; PDIP package (N20A) instead of SOIC (M20B); slightly higher ICC (62–90 mA vs 48–95 mA). | Through-hole assembly; less suitable for high-density SMT layouts but easier for prototyping and rework. | Select SN74LS245N for hand-soldered development boards or legacy through-hole production lines. |
| MC74LS245NG | Identical function and timing; ON Semiconductor rebrand; same SOIC-20 package; identical VCC/VIH/VIL thresholds and IOL/IOH ratings. | No functional difference; qualified to same JEDEC standards; available with alternate date-code traceability. | Choose MC74LS245NG when sourcing from ON Semi distribution channels or requiring dual-source assurance. |
Compared with DM74LS245WM, SN74LS245N offers through-hole mounting flexibility at the cost of board space, while MC74LS245NG provides identical performance in the same SOIC package with alternate supply-chain validation-both preserve full functional and timing compatibility for drop-in replacement where package constraints allow.
Availability
DM74LS245WM is available at Aetrix Electronics and suitable for industrial backplane interconnect, legacy computer system expansion, and programmable logic controller (PLC) I/O modules requiring stable component supply across extended product lifecycles.
Supply support for DM74LS245WM 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 specializing in analog and discrete power products, acquired by ON Semiconductor in 2016. Known for industry-standard logic families and robust industrial-grade ICs.
The DM74LS245WM belongs to Fairchild's 74LS logic series, designed specifically for high-reliability, noise-immune TTL-level bus interfacing in commercial-temperature industrial control and computing systems.
FAQ
What is the maximum operating temperature range for the DM74LS245WM?
The DM74LS245WM is rated for operation from 0°C to +70°C ambient temperature, per its Recommended Operating Conditions table. This commercial-grade range aligns with standard LS-TTL specifications and supports use in office equipment, test instruments, and non-automotive industrial controllers. The DM74LS245WM does not support extended or automotive temperature grades.
Does the DM74LS245WM support true bidirectional data flow on the same pins?
Yes, the DM74LS245WM supports true bidirectional data flow: pins 2–9 (A1–A8) and 11–18 (B1–B8) are bidirectional I/O terminals. Data direction (A→B or B→A) is controlled solely by the DIR input, and all outputs enter high-impedance state when G is HIGH. The DM74LS245WM achieves this without external direction-control logic or separate transmit/receive pins.
What is the purpose of hysteresis in the DM74LS245WM inputs?
Hysteresis (0.2–0.4 V) on all A and B bus inputs improves noise margin by creating distinct threshold voltages for rising and falling edges. This prevents oscillation or metastability when signals traverse electrically noisy environments such as long PCB traces or industrial cabling. The DM74LS245WM leverages this to maintain reliable operation without external filtering in real-world backplane applications.
Can the DM74LS245WM be used with 3.3 V logic systems?
No, the DM74LS245WM is not designed for 3.3 V operation. Its absolute maximum input voltage on A/B pins is 5.5 V, and it requires VCC = 4.75–5.25 V for guaranteed functionality. Input thresholds (VIH = 2.0 V, VIL = 0.8 V) are optimized for 5 V TTL, and interfacing with 3.3 V systems requires level-shifting circuitry. The DM74LS245WM remains strictly a 5 V-only device.
How does the PNP input structure benefit system design?
Each input of the DM74LS245WM uses a PNP transistor structure, limiting DC input current to ≤0.1 mA per pin-even at VI = 5.5 V. This reduces cumulative loading on upstream drivers, allowing more devices per bus segment and improving signal integrity on long or heavily loaded traces. The DM74LS245WM thus extends fanout capability beyond standard TTL while maintaining compatibility.
DM74LS245WM Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- 74LS
- Package/Case:
- 20-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:
- -
- Current - Output High, Low:
- 15mA, 24mA
- Voltage - Supply:
- 4.75V ~ 5.25V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SOIC
DM74LS245WM FAQ
1.How can I place an order for DM74LS245WM through Aetrix?
Please submit a Request for Quotation (RFQ) for DM74LS245WM 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 DM74LS245WM reliable?
The price and inventory of DM74LS245WM are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DM74LS245WM is usually 5 days.
3.What payment methods are accepted for DM74LS245WM?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DM74LS245WM transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DM74LS245WM?
DM74LS245WM orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DM74LS245WM 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 DM74LS245WM?
For technical support, including DM74LS245WM datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DM74LS245WM requirements.
6.How does Aetrix verify that DM74LS245WM is sourced from the original manufacturer or authorized distributors?
All DM74LS245WM 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 DM74LS245WM meets industry standards.
7.What is the process for return or replacement of DM74LS245WM?
All DM74LS245WM units undergo pre-shipment inspection (PSI). If there is an issue with DM74LS245WM, 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 DM74LS245WM part is unused and in its original packaging.
Return procedure for DM74LS245WM:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
DM74LS245WM Tags
-
SN74LVC1G17DBVR
Texas Instruments
-
SN74LVC1G07DCKR
Texas Instruments
-
SN74LVC1G17DCKR
Texas Instruments
-
SN74LVC1G07DBVR
Texas Instruments
-
SN74LVC1G125DCKR
Texas Instruments
-
SN74AHCT1G126DBVR
Texas Instruments
-
SN74LVC1G125DBVR
Texas Instruments
-
SN74AHCT1G125DBVR
Texas Instruments
-
SN74LVC2G17DBVR
Texas Instruments
-
SN74LVC2G07DCKR
Texas Instruments
-
SN74LVC1G34DCKR
Texas Instruments
-
SN74LVC2G17DCKR
Texas Instruments
Tech Hub
Counterfeit components can hide behind convincing markings and passing basic function tests. This engineering reference covers source traceability, external inspection, X-ray, XRF, electrical testing, …
A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
