Part A
74HC4066D
Toshiba Semiconductor and Storage
- Lifecycle
- Active
- Stock
- 7546 PCS
- Package
- SOIC-14
- Series
- Interface - Conmutadores analógicos, Multiplexers, Demultiplexeres
Replacement verdict
Not a drop-in replacement
The 74HC4051D and 74HC4066D are not functionally interchangeable despite sharing the same 74HC CMOS logic family and SO16 package. The 74HC4051D is an 8-channel analog multiplexer/demultiplexer with a single common I/O and three digital address-select inputs, whereas the 74HC4066D contains four independent bilateral analog switches, each with its own control input. This fundamental architectural difference in signal routing, channel count, and control interface means the two devices cannot be substituted for one another in existing designs without significant circuit redesign.
Different switch architecture
Different channel count
Different control interface
Different signal routing
Parts at a glance
Part B
74HC4051D
Toshiba Semiconductor and Storage
- Lifecycle
- Active
- Stock
- 5871 PCS
- Package
- SOIC-14
- Series
- Interface - Conmutadores analógicos, Multiplexers, Demultiplexeres
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74HC4051D | 74HC4066D | Why it matters |
|---|---|---|---|
| Function / Configuration | 8-channel analog multiplexer/demultiplexer (1-of-8) | Quad bilateral analog switch (4 independent SPST) | Defines the core signal-routing topology; a mux selects one of eight channels, while the 4066 provides four independent on/off switches, so they are not directly interchangeable. |
| Number of Switches / Channels | 1 common channel to 8 selectable channels | 4 independent bilateral switches | Determines how many signals can be routed or controlled simultaneously in a design. |
| Control Inputs | 3 binary select inputs (S0-S2) plus enable (E) | 4 independent control inputs (one per switch) | Affects the logic interface and the number of GPIO lines needed to operate the device. |
| On-Resistance (typ.) | ~80 Ω at VCC = 4.5 V | ~50 Ω at VCC = 4.5 V | Lower on-resistance reduces signal attenuation and voltage drop across the switch, which is important for analog signal integrity. |
| Propagation Delay (typ.) | ~4 ns at VCC = 4.5 V | ~5 ns at VCC = 4.5 V | Influences maximum usable switching frequency and timing accuracy in signal-routing applications. |
| Package | SO16 (16-pin SOIC) | SO14 (14-pin SOIC) | Different pin counts and footprints prevent drop-in PCB replacement without layout changes. |
| Supply Voltage Range | 2 V to 6 V | 2 V to 6 V | Both support the same logic-level supply range, allowing use in 3.3 V and 5 V systems. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | Identical temperature ratings mean both are suitable for industrial and automotive-grade environments. |
| Analog Signal Range | VEE to VCC (rail-to-rail with dual supply) | VSS to VDD (rail-to-rail) | Determines the allowable analog signal swing; the 4051 supports bipolar signals with a negative VEE rail, while the 4066 is typically used with a single positive supply. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC4066D | 74HC4051D |
|---|---|---|
| Part Status | Active | Active |
| Multiplexer / Demultiplexer Circuit | 1:1 | 8:1 |
| Number of Circuits | 4 | 1 |
| On - State Resistance(Max) | 80Ohm | 130Ohm |
| Channel - to - Channel Matching(ΔRon) | 5Ohm (Typ) | 4Ohm |
| Voltage - Supply, Single (V+) | 2V ~ 12V | 2V ~ 6V |
| Switch Time(Ton Toff)(Max) | 12ns, 12ns | 34ns, 32ns |
| -3 dB Bandwidth | 200MHz | - |
| Channel Capacitance(CS(off)CD(off)) | 3pF | 10pF |
| Current - Leakage(IS(off))(Max) | 100nA | 1µA |
| Crosstalk | -60dB @ 1MHz | -50dB @ 1MHz |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C (TA) |
| Mounting Type | Surface Mount | Surface Mount |
Frequently asked questions
What is the main functional difference between the 74HC4051D and the 74HC4066D?
The 74HC4051D is an 8-channel analog multiplexer/demultiplexer with a single common input/output and eight selectable channels controlled by three binary address inputs. The 74HC4066D contains four independent bilateral analog switches, each with its own control input, allowing four separate signal paths to be switched simultaneously or independently.
Can the 74HC4051D and 74HC4066D be used interchangeably in a circuit?
No. They are functionally different devices. The 74HC4051D provides one-of-eight channel selection via address decoding, while the 74HC4066D provides four independent SPST switches. Direct substitution is not possible without redesigning the signal routing and control logic.
What are the typical supply voltage ranges for the 74HC4051D and 74HC4066D?
Both devices are specified for operation over a wide supply voltage range. The 74HC4051D and 74HC4066D typically operate from 2 V to 10 V for the 74HC series, with some manufacturers specifying 2 V to 6 V for standard 74HC types. Always verify the exact range in the specific manufacturer datasheet.
What is the typical on-state resistance of these analog switches?
The 74HC4051D and 74HC4066D exhibit on-state resistance (Ron) that depends on supply voltage and temperature. At a 4.5 V supply, typical Ron is in the range of tens of ohms, while at higher supply voltages it decreases. For precise values, consult the manufacturer datasheet because Ron varies significantly with VCC and temperature.
How many control inputs does each device require?
The 74HC4051D requires three address inputs (S0, S1, S2) plus an enable input (E) to select one of eight channels. The 74HC4066D requires four independent control inputs, one for each of the four bilateral switches, with no address decoding or enable pin.
Are the 74HC4051D and 74HC4066D bidirectional?
Yes. Both devices are bidirectional. The 74HC4051D can route analog or digital signals in either direction between the common terminal and the selected channel. The 74HC4066D switches are bilateral, allowing signal flow in both directions through each switch.
What package types are commonly available for the 74HC4051D and 74HC4066D?
Both devices are commonly offered in SO16 (small outline) and other surface-mount packages, as well as DIP16 for through-hole applications. Package availability may vary by manufacturer, so confirm the specific orderable part number and package suffix in the manufacturer datasheet or distributor listing.
Which device is better for multiplexing multiple analog signals to a single ADC input?
The 74HC4051D is generally more suitable for multiplexing multiple analog signals to a single ADC input because it provides 8-to-1 channel selection with a single output. The 74HC4066D is better suited for independent switching of separate signal paths rather than channel multiplexing.