Part A
74HC244D
Toshiba Halbleiter und Speicher
- Lifecycle
- Active
- Stock
- 7745 Stückzahl
- Package
- SOIC-20
- Series
- Logic c Puffer, Treiber, Empfänger, Transceiver
Replacement verdict
Compatible functional replacement candidate
The 74HC244D and 74HC245D,652 are both octal non-inverting buffers from the 74HC family, but they are not pin-compatible drop-in replacements. The 74HC244D provides two groups of four buffers with independent output enable pins, while the 74HC245D,652 is a bidirectional transceiver with a direction control pin. Designers must account for differing pinout, control logic, and bidirectional capability before substituting.
Logic Function
Validation required
Pin Configuration
Not compatible
Control Interface
Not compatible
Supply Voltage Range
High match
Parts at a glance
Part B
74HC245D,652
NXP USA Inc.
- Lifecycle
- Active
- Stock
- 4100 Stückzahl
- Package
- SOIC-20
- Series
- Logic c Puffer, Treiber, Empfänger, Transceiver
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74HC244D | 74HC245D,652 | Why it matters |
|---|---|---|---|
| Logic Function | Octal Buffer/Line Driver with 3-state outputs, non-inverting, dual enable (1OE, 2OE) | Octal Bus Transceiver with 3-state outputs, non-inverting, direction control (DIR) and output enable (OE) | Determines whether the device can only buffer in one direction (244) or transmit bidirectionally (245), which is critical for bus-oriented designs. |
| Direction Control | Unidirectional (two groups of 4 buffers, each with its own enable) | Bidirectional (single 8-bit transceiver with DIR pin selecting A-to-B or B-to-A) | A bidirectional transceiver allows data flow in both directions on the same pins, while a unidirectional buffer only drives one way. |
| Number of Enable/Control Pins | 2 output enable pins (1OE, 2OE), each controlling 4 channels | 2 control pins (OE and DIR) | Affects how the device is controlled in a system; the 244 allows independent enabling of two 4-bit groups, while the 245 uses one enable plus a direction pin. |
| Supply Voltage Range | 2.0 V to 6.0 V | 2.0 V to 6.0 V | Defines the compatible logic families and power rails; both support 2 V to 6 V HC-family operation. |
| Output Type | 3-state (tri-state) non-inverting | 3-state (tri-state) non-inverting | Tri-state outputs allow the device to be disconnected from a shared bus, which is essential for bus multiplexing. |
| Number of Channels | 8 (two groups of 4) | 8 | Both provide 8 buffered channels, so channel count is not a differentiator for substitutability. |
| Package | SOIC-20 (D suffix) | SOIC-20 (D suffix) | Same package and pin count simplify PCB layout and potential drop-in replacement considerations. |
| Logic Family | 74HC (High-speed CMOS) | 74HC (High-speed CMOS) | Same logic family ensures compatible input thresholds, output drive, and speed characteristics. |
| Pin Function Compatibility | Pins include 1OE, 2OE, inputs A1-A4/B1-B4, outputs Y1-Y4/Y5-Y8 | Pins include DIR, OE, A1-A8, B1-B8 | Different pin functions mean the two devices are not pin-to-pin compatible despite sharing the same package. |
| Typical Application | Memory address drivers, clock drivers, and bus-oriented transmitters | Bidirectional bus interfacing between two buses or a bus and a peripheral | Application suitability differs; the 244 is used for one-way buffering, while the 245 is used where bidirectional data flow is required. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC244D | 74HC245D,652 |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC |
| Series | 74HC | 74HC |
| Part Status | Active | Active |
| Logic Type | Buffer, Non-Inverting | Transceiver, Non-Inverting |
| Number of Elements | 2 | 1 |
| Number of Bits per Element | 4 | 8 |
| Output Type | 3-State | 3-State |
| Current - Output High Low | 7.8mA, 7.8mA | 7.8mA, 7.8mA |
| Voltage - Supply | 2V ~ 6V | 2V ~ 6V |
| Operating Temperature | -40°C ~ 85°C (TA) | -40°C ~ 125°C (TA) |
| Mounting Type | Surface Mount | Surface Mount |
Frequently asked questions
What is the main functional difference between the 74HC244D and the 74HC245D,652?
The 74HC244D is an octal non-inverting buffer/line driver with 3-state outputs, featuring two active-low output enable pins (1OE and 2OE) that independently control two groups of four outputs. The 74HC245D,652 is an octal non-inverting bus transceiver with 3-state outputs, featuring a direction control pin (DIR) and an output enable pin (OE), allowing bidirectional data flow between two buses.
Are the 74HC244D and 74HC245D,652 pin-compatible?
No. The 74HC244D has two output enable pins (pins 1 and 19) and unidirectional data flow from inputs to outputs. The 74HC245D,652 has a direction pin (pin 1) and an output enable pin (pin 19), with bidirectional data flow. Although both are 20-pin devices, the pin functions differ, so they are not directly interchangeable without circuit redesign.
Can the 74HC244D be used as a drop-in replacement for the 74HC245D,652?
No. The 74HC244D cannot provide bidirectional data transfer because it lacks a direction control pin. The 74HC245D,652 requires a DIR pin to select transmit or receive mode. Substitution would require external logic or a redesign to emulate the transceiver function, and the pin functions are not compatible.
What are the output drive capabilities of the 74HC244D and 74HC245D,652?
Both devices are 74HC CMOS logic parts. Per standard 74HC family specifications, they typically provide ±6 mA output drive at 5 V VCC and ±4 mA at 4.5 V VCC, with symmetrical source and sink currents. These parameters are consistent across both the 74HC244D and 74HC245D,652 under the same supply voltage and temperature conditions.
What supply voltage range do the 74HC244D and 74HC245D,652 support?
Both devices operate over a supply voltage range of 2.0 V to 6.0 V, typical of the 74HC logic family. They are characterized for operation from -40 °C to +125 °C, depending on the specific manufacturer's datasheet. Always verify the exact limits in the manufacturer's datasheet for the specific part number.
What is the difference in propagation delay between the 74HC244D and 74HC245D,652?
Both devices have similar propagation delays because they use the same 74HC CMOS process. At 5 V VCC and 25 °C, typical propagation delay is approximately 10 ns to 15 ns for both. The 74HC245D,652 may have slightly different timing due to the bidirectional switch architecture, but the difference is not significant for most applications. Consult the specific manufacturer datasheet for exact values.
Which device is better for bidirectional bus applications?
The 74HC245D,652 is specifically designed for bidirectional bus applications because it includes a direction control pin (DIR) that allows data to flow from A to B or B to A. The 74HC244D is unidirectional and cannot perform bidirectional bus transfers without external circuitry. For any application requiring bidirectional data flow, the 74HC245D,652 is the appropriate choice.
What are the package options for the 74HC244D and 74HC245D,652?
The 74HC244D is typically offered in a 20-pin SOIC package (D suffix). The 74HC245D,652 is also offered in a 20-pin SOIC package, where "652" indicates a tape and reel packing option from Nexperia. Both are surface-mount devices with the same package footprint but different pin functions. Always confirm the exact package and packing designation from the manufacturer or authorized distributor.