CD74HC245M Texas Instruments In Stock
CD74HC245M is a high-speed CMOS octal bidirectional bus transceiver with 3-state outputs by Texas Instruments in a 20-pin SOIC package. Key specs: 8-bit bidirectional data paths, 2 V to 6 V supply range, and 25 mA output drive current per channel. From $0.20, in stock with worldwide shipping.
- Manufacturer
- Texas Instruments
- Package
- —
- Lifecycle
- ACTIVE
- Datasheet
- N/A
- RoHS
- Compliant
- Lead Time
- 3–7 business days
- Shipping
- DHL Express · Worldwide
Key Features
- 8-bit bidirectional bus transceiver with direction-control pin and output-enable, allowing full duplex data transfer between two independent 8-bit buses at 2 V to 6 V
- 25 mA output drive capability per channel enables driving heavily loaded backplane buses with multiple CMOS or TTL loads without external buffers
- HC-family CMOS with 2 V to 6 V supply compatibility enables bridging between 3.3 V and 5 V bus segments on mixed-voltage PCBs
- 3-state outputs on both A and B ports allow multiple CD74HC245M devices to share a common bus with active-high and active-low control signals
Applications
The CD74HC245M is a fundamental bus buffer used in microprocessor and FPGA designs to isolate and drive 8-bit data buses between different PCB sections or voltage domains. It is commonly deployed in memory interface boards, ISA bus expansions, and address/data bus drivers where bidirectional 8-bit data must flow between a processor and peripheral devices with 25 mA drive strength. The device also serves as a level-shift buffer between 3.3 V and 5 V logic sections when supply voltages differ between the host MCU and legacy peripherals.
Compliance & Regulatory
| RoHS Status | Compliant |
| Lead-Free | Yes (Pb-Free) |
Alternate & Equivalent Parts
No known alternates. Submit an RFQ and our team can suggest alternatives.
Frequently Asked Questions
What is the data bus width and drive current of each output channel in the CD74HC245M?
The CD74HC245M is an 8-bit octal transceiver, providing 8 bidirectional data paths between port A and port B. Each output is capable of sourcing or sinking 25 mA, which is substantially higher than standard HC-family inputs rated at 4 mA, enabling the device to drive backplane traces with multiple loads without signal degradation.
How does the CD74HC245M direction control work, and can both bus directions be driven simultaneously?
The CD74HC245M uses a single DIR pin to select data flow direction: when DIR is high, data flows from A to B, and when DIR is low, data flows from B to A. The OE (output enable) pin tri-states all 8 outputs on the active port. Both A and B ports cannot drive simultaneously, as the device is half-duplex, but the direction can be toggled in nanoseconds under software control for bidirectional bus arbitration.
What supply voltage range does the CD74HC245M support, and how does it handle 3.3 V to 5 V level translation?
The CD74HC245M operates from 2 V to 6 V supply. When powered at 5 V with a 3.3 V source on port A and a 5 V load on port B, the device passes 3.3 V HIGH inputs to the 5 V side where 3.3 V exceeds the HC-family VIH threshold of approximately 3.5 V at 5 V supply. For reliable level translation in mixed systems, powering the device at 3.3 V and using an open-drain buffer on the 5 V side is a more robust approach.
In what microprocessor bus interface designs is the CD74HC245M most commonly used?
The CD74HC245M is a standard component in 8-bit microprocessor bus buffers, ISA bus expansions, Z80 and 8051 data bus drivers, and FPGA I/O bank buffers where the processor's 8-bit data bus must drive multiple peripheral ICs simultaneously. A single CD74HC245M at 25 mA output per line can drive 5 to 8 HC-family peripheral inputs without pull-up resistors, simplifying the bus interface circuit.
How does the CD74HC245M compare to the 74HC244 unidirectional buffer for a memory interface design?
The CD74HC245M has 8 bidirectional channels with a direction pin, making it the correct choice for read/write memory interfaces where data must flow both from CPU to memory (write) and from memory to CPU (read). The 74HC244 has 8 unidirectional channels and is better suited for address bus buffering where data flows in only one direction. Using the CD74HC245M replaces two 74HC244 ICs in a bidirectional application, halving the IC count and shrinking the PCB footprint by approximately 50%.
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About Texas Instruments
Texas Instruments (TI) is a global semiconductor company headquartered in Dallas, Texas. TI designs and manufactures analog and embedded processing chips used in industrial, automotive, consumer, communications, and enterprise systems.
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