Part A
74HC245D
Toshiba Halbleiter und Speicher
- Lifecycle
- Active
- Stock
- 4218 Stückzahl
- Package
- SOIC-14
- Series
- Logic c Puffer, Treiber, Empfänger, Transceiver
Replacement verdict
Compatible functional replacement candidate
The 74HC245D and 74HC244D,653 are both octal non-inverting buffers from the 74HC family, sharing identical supply voltage range, package type, and logic function characteristics. The primary distinction lies in the direction control architecture: the 74HC245D provides bidirectional transceiver capability with a direction pin, while the 74HC244D,653 offers dual enable control for unidirectional signal flow. For applications requiring unidirectional buffering with independent enable control, the 74HC244D,653 is a viable substitute; however, designs relying on bidirectional data flow must account for the absence of direction control in the 74HC244D,653.
Logic Function
High match
Supply Voltage Range
High match
Package Type
High match
Direction Control
Validation required
Parts at a glance
Part B
74HC244D,653
NXP USA Inc.
- Lifecycle
- Active
- Stock
- 6812 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 | 74HC245D | 74HC244D,653 | Why it matters |
|---|---|---|---|
| Logic Function | Octal bus transceiver, non-inverting, 3-state | Octal buffer/line driver, non-inverting, 3-state | Determines the core function: the 245 can transmit data bidirectionally, while the 244 only buffers in one direction, so they are not directly substitutable in bidirectional bus applications. |
| Direction Control | Direction pin (DIR) selects A-to-B or B-to-A | Fixed direction (A inputs to Y outputs) | The 245 supports bidirectional data flow via a direction control pin, whereas the 244 has a fixed signal path, affecting board routing and system architecture. |
| Number of Channels | 8 | 8 | Both devices provide eight channels, so bus width is identical and does not limit substitutability. |
| Output Enable Control | Active-LOW Output Enable (OE) | Two active-LOW Output Enables (1OE, 2OE) | The 244 splits enable control across two 4-bit groups, allowing independent half-bus control, while the 245 enables all eight channels together. |
| Supply Voltage Range | 2.0 V to 6.0 V | 2.0 V to 6.0 V | Identical supply range means both can operate in the same 2 V to 6 V logic systems without voltage-level concerns. |
| Output Drive Current | ±6 mA (typical at 4.5 V) | ±6 mA (typical at 4.5 V) | Matching drive current indicates similar fan-out and line-driving capability, supporting comparable load handling. |
| Propagation Delay | ~13 ns (typical at 4.5 V) | ~13 ns (typical at 4.5 V) | Similar propagation delay means timing performance is comparable, so speed-critical designs are not disadvantaged by substitution. |
| Package | SOIC-20 (D suffix) | SOIC-20 (D suffix) | Identical package and pin count allow the same PCB footprint, though pin functions differ and must be verified before direct replacement. |
| Pin Count | 20 | 20 | Same pin count supports mechanical compatibility, but electrical pin assignments differ between the two devices. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | Identical temperature range ensures both parts are suitable for the same industrial and automotive-grade environments. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC245D | 74HC244D,653 |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC |
| Series | 74HC | 74HC |
| Part Status | Active | Active |
| Logic Type | Transceiver, Non-Inverting | Buffer, Non-Inverting |
| Number of Elements | 1 | 2 |
| Number of Bits per Element | 8 | 4 |
| 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 ~ 125°C (TA) | -40°C ~ 125°C (TA) |
| Mounting Type | Surface Mount | Surface Mount |
Frequently asked questions
What are the main functional differences between the 74HC245D and the 74HC244D,653?
The 74HC245D is an octal bus transceiver with non-inverting 3-state outputs, designed for bidirectional data transfer between two buses. The 74HC244D,653 is an octal buffer/line driver with non-inverting 3-state outputs, intended for unidirectional data flow. The 74HC245D has a direction control (DIR) pin and an output enable (OE) pin, while the 74HC244D,653 has two active-low output enable pins (1OE and 2OE) that control four outputs each.
Can the 74HC245D and 74HC244D,653 be used interchangeably in a design?
No, they are not pin-to-pin or functionally interchangeable. The 74HC245D provides bidirectional data transfer with a DIR pin, whereas the 74HC244D,653 provides unidirectional buffering with separate enable pins for two 4-bit groups. Substitution requires verifying pinout, control logic, and signal flow requirements against the target design.
What are the package and pin count differences between the 74HC245D and the 74HC244D,653?
Both devices are typically offered in a 20-pin SOIC package (the "D" suffix in 74HC245D and the "D" in 74HC244D,653 indicates SOIC). The 74HC245D uses 20 pins for bidirectional transceiver functions, while the 74HC244D,653 uses 20 pins for octal buffer functions with two enable pins. Pin assignments differ, so PCB land patterns and connections are not identical.
What are the output drive capabilities of the 74HC245D and 74HC244D,653?
Both devices are 74HC CMOS logic parts and typically provide symmetrical output drive. Standard 74HC specifications list a output current of ±4 mA at 5 V for both the 74HC245D and the 74HC244D,653, with similar propagation delays and input/output voltage characteristics. Always confirm exact drive strength from the specific manufacturer datasheet.
How do the control inputs differ between the 74HC245D and the 74HC244D,653?
The 74HC245D has an output enable (OE) pin and a direction control (DIR) pin. When OE is active, DIR selects whether data flows from A to B or from B to A. The 74HC244D,653 has two active-low output enable pins (1OE and 2OE), each controlling four outputs, with no direction control because data flow is fixed from input to output.
Are the 74HC245D and 74HC244D,653 compatible with 5 V and 3.3 V logic systems?
Both are 74HC family devices and are typically specified for operation from 2 V to 6 V, making them compatible with 5 V and 3.3 V logic levels when used within the recommended supply range. However, input thresholds and output levels vary with supply voltage, so verify the specific datasheet for the target VCC and logic-level requirements.
Which device is better for bidirectional bus applications?
The 74HC245D is the appropriate choice for bidirectional bus applications because it includes a direction control pin that allows data to flow in either direction between two buses. The 74HC244D,653 is unidirectional and cannot reverse data flow, so it is not suitable for bidirectional bus interfacing without external logic.
What are the typical propagation delay and operating temperature ranges for these devices?
Both the 74HC245D and 74HC244D,653 are standard 74HC CMOS devices. Typical propagation delay is in the range of 8 ns to 20 ns depending on supply voltage and load, and the operating temperature range is typically -40 °C to +125 °C for industrial-grade versions. Confirm exact values from the manufacturer datasheet for the specific part number and grade.