Part A
74HC245D,653
NXP Hoa Kỳ Inc.
- Lifecycle
- Active
- Stock
- 8186 PCS
- Series
- Logic - Buffers, Drivers, Receivers, Transceivers
Replacement verdict
Compatible functional replacement candidate
The 74HC244D and 74HC245D,653 are both octal non-inverting buffers from the 74HC family, sharing identical supply voltage, logic levels, and temperature ranges. However, the 74HC244D provides unidirectional buffering with dual active-low output enables, while the 74HC245D,653 offers bidirectional transceiver functionality with direction control and a single active-low output enable. This fundamental difference in data flow architecture means the 74HC245D,653 can serve as a functional replacement for the 74HC244D in unidirectional applications by tying the direction pin appropriately, but the reverse substitution requires careful validation of bidirectional requirements. Designers should verify pinout compatibility and control signal logic before committing to a drop-in replacement.
Function Type
Validation required
Supply Voltage
High match
Package Type
High match
Control Logic
Validation required
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,653 | 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 can transmit bidirectionally (245), which is critical for bus-oriented designs. |
| Direction Control | Unidirectional (fixed input-to-output) | Bidirectional via DIR pin | A bidirectional transceiver allows data flow in either direction, enabling use on shared buses; a unidirectional buffer cannot. |
| Number of Enable/Control Pins | 2 output enable pins (1OE, 2OE), each controlling 4 channels | 1 output enable (OE) and 1 direction (DIR) pin | Affects how the device is controlled in a system; the 244 allows split enabling of two 4-bit groups, while the 245 uses a single OE plus direction control. |
| 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–6 V, making them interchangeable in many 3.3 V and 5 V systems. |
| 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 bus, which is essential for shared-bus architectures. |
| Number of Channels | 8 (octal) | 8 (octal) | Both provide eight buffered lines, so the channel count is not a differentiator for substitutability. |
| Package | SOIC-20 (D suffix) | SOIC-20 (D suffix) | Identical package and pin count simplify PCB layout and allow drop-in replacement considerations. |
| Propagation Delay (typical at 5 V) | ~11 ns | ~11 ns | Similar propagation delay means timing performance is comparable, so neither device introduces a significant speed penalty. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | Both cover the industrial temperature range, making them suitable for the same environmental conditions. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC245D,653 | 74HC244D |
|---|---|---|
| Series | 74HC | 74HC |
| Part Status | Discontinued at DigiKey | Active |
| Base Product Number | 74HC245 | - |
| 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 | - |
| Voltage - Supply | 2V ~ 6V | 2V ~ 6V |
| Operating Temperature | -40°C ~ 125°C (TA) | -40°C ~ 85°C (TA) |
| Mounting Type | Surface Mount | Surface Mount |
| Packaging | Tape & Reel (TR) | - |
| Current - Output High Low | - | 7.8mA, 7.8mA |