Part A
74HC126D
Toshiba Semiconductor and Storage
- Lifecycle
- Active
- Stock
- 7257 PCS
- Package
- SOIC-14
- Series
- Logic - Buffers, Drivers, Receivers, Transceivers
Replacement verdict
Not a drop-in replacement
The 74HC126D and 74HC154D,652 are functionally unrelated devices and cannot serve as substitutes for one another. The 74HC126D is a quad bus buffer with 3-state outputs, while the 74HC154D,652 is a 4-to-16 line decoder/demultiplexer. Their logic functions, pin configurations, and output characteristics differ fundamentally, making direct replacement impossible without complete circuit redesign.
Different logic function
Different output type
Different pin count
Different package footprint
Parts at a glance
Part B
74HC154D,652
NXP USA Inc.
- Lifecycle
- Active
- Stock
- 2528 PCS
- Package
- SOIC-24
- Series
- Logic - Signal Switches, Multiplexers, Decoders
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74HC126D | 74HC154D,652 | Why it matters |
|---|---|---|---|
| Logic Function | Quad Buffer with 3-State Outputs | 4-to-16 Line Decoder/Demultiplexer | The core logic function determines whether the devices are functionally interchangeable; these two parts perform entirely different operations. |
| Number of Channels / Outputs | 4 buffers | 16 outputs | Channel count affects how many signals can be handled simultaneously in a circuit design. |
| Output Type | 3-State | Active-Low (standard push-pull) | 3-state outputs allow bus sharing, while standard outputs cannot be tied together without contention. |
| Control Inputs | Output Enable (active-High) per buffer | 4 address inputs plus 2 enable inputs (active-Low) | The control scheme dictates how the device is driven and whether it fits the intended logic design. |
| Package | SOIC-14 | SOIC-24 | Package footprint and pin count must match the PCB layout for physical compatibility. |
| Pin Count | 14 | 24 | Different pin counts mean the parts are not drop-in replacements on the same footprint. |
| Supply Voltage Range | 2 V to 6 V | 2 V to 6 V | Both operate over the standard HC-family supply range, so system voltage compatibility is equivalent. |
| Logic Family | 74HC (High-Speed CMOS) | 74HC (High-Speed CMOS) | Same logic family ensures comparable input thresholds, noise margins, and drive characteristics. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | Matching temperature ranges confirm both parts suit the same environmental conditions. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC126D | 74HC154D,652 |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC |
| Series | 74HC | 74HC |
| Part Status | Active | Active |
| Type | - | Decoder/Demultiplexer |
| Circuit | - | 1 x 4:16 |
| Independent Circuits | - | 1 |
| Current - Output High Low | 7.8mA, 7.8mA | 5.2mA, 5.2mA |
| Voltage Supply Source | - | Single Supply |
| Voltage - Supply | 2V ~ 6V | 2V ~ 6V |
| Operating Temperature | -40°C ~ 125°C (TA) | -40°C ~ 125°C |
| Mounting Type | Surface Mount | Surface Mount |
| Logic Type | Buffer, Non-Inverting | - |
| Number of Elements | 4 | - |
| Number of Bits per Element | 1 | - |
| Output Type | 3-State | - |
Frequently asked questions
What are the primary functional differences between the 74HC126D and the 74HC154D,652?
The 74HC126D is a quad non-inverting buffer/line driver with 3-state outputs, while the 74HC154D,652 is a 4-to-16 line decoder/demultiplexer. The 74HC126D provides four independent buffer channels with active-HIGH output enable pins, whereas the 74HC154D,652 decodes a 4-bit binary input into one of sixteen mutually exclusive active-LOW outputs.
Are the 74HC126D and 74HC154D,652 pin-compatible?
No. The 74HC126D is typically supplied in a 14-pin SOIC package, while the 74HC154D,652 is supplied in a 24-pin SOIC package. They have different pin counts, pin assignments, and package dimensions, so they are not pin-compatible or directly interchangeable.
Can the 74HC126D be used as a drop-in replacement for the 74HC154D,652 in a decoder application?
No. The 74HC126D is a quad 3-state buffer and cannot perform 4-to-16 decoding. The 74HC154D,652 provides 16 decoded active-LOW outputs from a 4-bit input, a function the 74HC126D does not implement. Substitution would require a complete redesign of the decoding logic.
What are the supply voltage and logic family specifications for both devices?
Both the 74HC126D and the 74HC154D,652 are members of the 74HC high-speed CMOS logic family. They are specified for a nominal supply voltage range of 2.0 V to 6.0 V, with typical operation at 5.0 V. Both devices feature standard CMOS input thresholds and are compatible with LSTTL output levels when operated at 5.0 V.
How do the output drive capabilities of the 74HC126D and 74HC154D,652 compare?
Both devices are specified with standard 74HC output drive. At a 5.0 V supply, each output typically sinks or sources up to 4 mA while maintaining valid logic levels, with a maximum output current rating of ±25 mA per output. The 74HC126D provides 3-state outputs, while the 74HC154D,652 provides active-LOW decoded outputs without a high-impedance state.
What is the function of the enable inputs on each device?
The 74HC126D has four independent active-HIGH output enable (OE) pins, one per buffer channel. When OE is HIGH, the corresponding output is active; when OE is LOW, the output is in a high-impedance state. The 74HC154D,652 has two active-LOW enable inputs (E1 and E2); both must be LOW to enable decoding, and if either is HIGH, all sixteen outputs remain HIGH.
Which device is suitable for bus-oriented data transmission and why?
The 74HC126D is suitable for bus-oriented transmission because its 3-state outputs allow multiple devices to share a common bus. When disabled, its outputs present a high-impedance state, effectively disconnecting from the bus. The 74HC154D,652 does not have 3-state outputs and is intended for decoding or demultiplexing applications rather than direct bus driving.
Do the 74HC126D and 74HC154D,652 have the same operating temperature range?
Yes. Both devices are typically specified for the standard industrial operating temperature range of -40 °C to +125 °C, as defined by their respective manufacturer datasheets. This range is common to the 74HC logic family for both commercial and industrial grade versions.