Part A
74HC594D
Toshiba Semiconductor và lưu trữ
- Lifecycle
- Active
- Stock
- 1976 PCS
- Package
- SOIC-16
- Series
- Logic - Shift Registers
Replacement verdict
Compatible functional replacement candidate
The 74HC595D,118 and 74HC594D are functionally related 8-bit serial-in/serial or parallel-out shift registers with output latches, but they are not pin-compatible drop-in replacements. The 74HC595D,118 provides a serial data output for cascading and a direct asynchronous reset, while the 74HC594D offers a separate storage register clock and a direct clear. Designers must verify the control signal timing and cascade requirements before substituting one for the other.
Function
High match
Output Type
Validation required
Pin Configuration
Not compatible
Control Interface
Validation required
Parts at a glance
Part B
74HC595D,118
NXP Hoa Kỳ Inc.
- Lifecycle
- Active
- Stock
- 2450 PCS
- Package
- SOIC-16
- Series
- Logic - Shift Registers
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 74HC595D,118 | 74HC594D | Why it matters |
|---|---|---|---|
| Output Register Type | Serial-in, parallel-out with 8-bit storage register and 8-bit shift register | Serial-in, parallel-out with 8-bit storage register and 8-bit shift register | Both devices provide an 8-bit shift register and an 8-bit storage register, but the 74HC595 has separate serial output (Q7') while the 74HC594 has a direct serial output from the shift register; this affects cascading and data timing. |
| Number of Pins | 16 | 16 | Pin count is identical, but pin functions differ (e.g., 74HC595 has output enable OE and serial output Q7', while 74HC594 has a direct serial output and no OE). This impacts PCB layout and substitutability. |
| Output Enable (OE) Pin | Yes (active low) | No | The 74HC595 can tri-state its parallel outputs via OE, allowing bus sharing; the 74HC594 lacks this feature, so it cannot be used in applications requiring output disabling. |
| Serial Output Type | Q7' (serial output from shift register, available after 8th clock) | Q7' (serial output from shift register, available after 8th clock) | Both provide a serial output for cascading, but the 74HC595's Q7' is always active, while the 74HC594's Q7' is also always active; however, the 74HC595 has an additional OE that can affect output state. |
| Latch/Storage Register Clock | Separate latch clock (STCP) and shift clock (SHCP) | Separate latch clock (RCLK) and shift clock (SRCLK) | Both have independent clocks for shifting and latching, but pin names differ; this affects direct drop-in replacement without logic changes. |
| Reset Function | Asynchronous reset (MR) clears shift register | Asynchronous reset (MR) clears shift register | Both have active-low master reset, but the 74HC595's reset also affects the storage register? No, it only clears the shift register; the 74HC594's reset clears the shift register only. This is functionally similar. |
| Supply Voltage Range | 2 V to 6 V | 2 V to 6 V | Both operate over the same voltage range, making them compatible with common 3.3 V and 5 V logic systems. |
| Output Drive Current | ±6 mA (at 4.5 V) | ±6 mA (at 4.5 V) | Identical drive strength means both can drive similar loads such as LEDs or logic inputs directly. |
| Package Type | SOIC-16 (D) | SOIC-16 (D) | Same package footprint allows physical interchangeability on a PCB, but pin functions must be verified for correct operation. |
| Propagation Delay | Typical 15 ns at 5 V | Typical 15 ns at 5 V | Similar timing performance ensures both can be used in high-speed serial-to-parallel conversion without significant speed penalties. |
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Send your BOM and application constraints for technical and sourcing review.
Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 74HC594D | 74HC595D,118 |
|---|---|---|
| Series | 74HC | 74HC |
| Part Status | Active | Active |
| Logic Type | Shift Register | Shift Register |
| Output Type | Push-Pull | Tri-State |
| Number of Elements | 1 | 1 |
| Number of Bits per Element | 8 | 8 |
| Function | Serial to Parallel, Serial | Serial to Parallel, Serial |
| Voltage - Supply | 2V ~ 6V | 2V ~ 6V |
| Operating Temperature | -40°C ~ 125°C | -40°C ~ 125°C |
| Mounting Type | Surface Mount | Surface Mount |
Frequently asked questions
What is the main functional difference between the 74HC595D,118 and the 74HC594D?
The 74HC595D,118 is an 8-bit serial-in, parallel-out shift register with a separate storage register and 3-state output buffers. The 74HC594D is an 8-bit serial-in, parallel-out shift register with a separate storage register but without 3-state output buffers; its parallel outputs are always active.
Are the 74HC595D,118 and 74HC594D pin-compatible?
No. The 74HC595D,118 includes an output enable (OE) pin that controls the 3-state outputs, while the 74HC594D does not have an OE pin. The pin functions and package pinouts therefore differ, so they are not direct drop-in replacements.
Can the 74HC595D,118 and 74HC594D be used in the same serial data chain?
Yes, both devices use a serial data input, a shift clock, a storage register clock (latch), and a serial data output for cascading. However, the 74HC595D,118 also requires proper control of the output enable pin, whereas the 74HC594D outputs are always enabled.
What is the operating voltage range for the 74HC595D,118 and 74HC594D?
Both devices are 74HC-family CMOS logic devices and operate over a supply voltage range of 2.0 V to 6.0 V, as specified in the respective manufacturer datasheets.
Do both devices have the same output drive capability?
Both the 74HC595D,118 and 74HC594D provide standard 74HC-family output drive, typically ±4 mA at 5 V supply. However, the 74HC595D,118 has 3-state outputs that can be placed in high-impedance mode, while the 74HC594D outputs are always active.
Which device should be selected when output isolation is required?
The 74HC595D,118 should be selected when output isolation is required, because its 3-state output buffers can be disabled via the OE pin, placing the parallel outputs in high-impedance state. The 74HC594D does not provide this function.
Are the 74HC595D,118 and 74HC594D available in the same package type?
Both devices are commonly offered in SO16 (SOIC-16) packages, but the specific orderable part numbers and package options vary by manufacturer. The 74HC595D,118 is a specific ordering code from Nexperia for the 74HC595 in SO16 package. The 74HC594D is available from multiple manufacturers in SO16 and other package options. Always verify the exact package and ordering code from the manufacturer datasheet.
Can the 74HC594D replace the 74HC595D,118 in an existing design?
Only if the design does not require 3-state output capability and the PCB layout can accommodate the different pinout. The 74HC594D lacks the OE pin, so any design relying on high-impedance output states or output enable control cannot use the 74HC594D as a direct substitute.